what is the purpose of changing the eluting solvent from pentane to ether between the two fractions? please explain your answer, being sure to mention important intermolecular forces and how they relate to the compounds being eluted

Answers

Answer 1

We are aware that ether is a polar solvent and pentane is an apolar one. The less polar material moves quicker while more polar component travels slower.

By use of polar interactions, the sample that has to be separated will be adsorbed to the stationary phase comprised of alumina or silica gel. The eluting solvent will be used to elute these adsorbed molecules. Both polar and non-polar solvents may be used as these eluting agents. The interactions with the polar molecules that are adsorbed to the chromatographic column grow when the polarity of the eluting solvent is increased. Pentane is less polar than ether when compared. As a result, polar molecules are separated from and eluted from the stationary phase using ether. This is due to the fact that polar solvents may dissolve polar substances due to polar interactions.

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Related Questions

consider the six hypothetical electron states listed in the table.which, if any, of these states are not possible?

Answers

3,5,6 electron states are not possible.

The first state is possible, as it has an n value of 1 and an l value of 0, which corresponds to the 1s orbital.

The second state is possible, as it has an n value of 1 and an l value of 1, which corresponds to the 2p orbital. The third state is possible, as it has an n value of 2 and an l value of 1, which corresponds to the 3p orbital.

The fourth state is possible, as it has an n value of 2, an l value of 1, and an m value of 1, which corresponds to the 3px orbital. The fifth state is possible, as it has an n value of 2, an l value of 2, and an m value of 0, which corresponds to the 3dxy orbital.

The sixth state is not possible, as it violates the Pauli exclusion principle by having two electrons with the same set of quantum numbers. In particular, it has an n value of 3, an l value of 1, an m value of 1, and an ms value of -1/2, which is identical to the fourth state.

The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers, and the fourth and sixth states have the same set of quantum numbers. Therefore, the sixth state is not possible.

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Complete question

consider the six hypothetical electron states listed in the table. which, if any, of these states are not possible?

n l m m s

1 0 0 +1/2

1 1 0 +1/2

2 1 0 -1/2

2 1 1 +1/2

2 2 0 -1/2

3 1 1 -1/2

arrange the atoms: ca, br, ge, rb, in order of increasing atomic radius. only type in the chemical symbols in the blanks.____ > ____ > ____ > ____

Answers

The arrangement of atoms ca, br, ge, rb, in order of increasing atomic radius is : Rb > Ca > Ge > Br

Atomic radius is the distance between the nucleus and the outermost shell of an atom. The periodic table indicates a general pattern in the way atomic radius varies across the table. The atomic radius depends on the number of protons, electrons, and neutrons in an atom, as well as the electron configuration and the shielding effect. Atomic radius increases from top to bottom within a group and decreases from left to right across a period. To arrange in the order of atomic radius, we generally follow the above rule also here are the atomic radii of the given atoms, according to the periodic table trends: Ca (calcium): 197 pm, Br (bromine): 115 pm, Ge (germanium): 125 pm, Rb (rubidium): 247 pm. Based on this data, we can arrange the atoms in order of increasing atomic radius as follows:Br > Ge > Ca > Rb

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At what tempreture oxygen can be liquefied

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Oxygen can be liquefied at a temperature of -182.96°C (-297.33°F) at standard atmospheric pressure (1 atm or 101.3 kPa).

This is the boiling point of oxygen, which is the temperature at which oxygen changes from a gas to a liquid at constant pressure. To liquefy oxygen, it must be cooled to a temperature below its boiling point while maintaining a pressure of at least 1 atm. At lower pressures, the boiling point of oxygen decreases, so it can be liquefied at lower temperatures. Ammonia has a critical temperature of 405.5 K, which is greater than the ambient temperature. Since oxygen's critical temperature is lower than that of air, it cannot liquefy at room temperature.

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How can you tell that all the circles represent an
element?
A. They do not represent an element

B. They are all the same shape, size, and color.

Answers

They are all the same shape, size, and color.

How do you know the circles that represent an element in a model?

We know that we have the elements the compounds and the mixtures and we may sometimes use a model to show all of these that I have spoken of here.

Since the elements has to be the same, this implies that they arethe same  in nature and we have to show them by the use of the exact same type of representation when we produce any kind of model that we have. Thus, they are all the same shape, size, and color.

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PLEASE HELP i don know how to do Single replacement rxn

Answers

Answer:itd a bro

Explanation:dont trust just need points

D. Single replacement means just one element has traded places. In this case it’s the zinc swapping places with the zag

vapor pressure primarily depends on two factors. one factor is the types of intermolecular forces present; what is the other?

Answers

Vapor pressure primarily depends on two factors: the types of intermolecular forces present and the temperature.
The temperature affects the amount of kinetic energy that molecules have. Molecules with higher kinetic energy move faster, resulting in increased collisions with the container walls. These increased collisions lead to increased vapor pressure.

Vapor pressure primarily depends on two factors. One factor is the types of intermolecular forces present; the other factor is temperature. Vapor pressure is the measure of the tendency of a substance to evaporate or vaporize. It is the pressure exerted by a gas at equilibrium with its liquid or solid state. The vapor pressure depends on the temperature of the substance and the type of intermolecular forces present.The other factor that primarily depends on the vapor pressure is temperature. Vapor pressure and temperature are inversely proportional to each other. At a higher temperature, the vapor pressure is higher, and at a lower temperature, the vapor pressure is lower. When the temperature is increased, the kinetic energy of the molecules increases, which results in more molecules breaking away from the liquid surface and escaping into the gas phase.Therefore, the vapor pressure primarily depends on two factors, one of which is the types of intermolecular forces present, and the other is the temperature of the substance.

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A solution is prepared by taking 25.0 mL of a stock solution of NaOH and diluting it to a final volume of 350. mL. the molarity of the diluted solution is 0.042 m. Which of the following options correctly describe these solutions? select all that apply.
a. The portion of stock solution used contained 0.0147 moles of NaOH. b. The stock solution has a molarity of 0.59M. c. The stock solution has a molarity of 0.030M. d. The 350.mL of diluted solution contains 0.042 moles of NaOH

Answers


Explanation:

The amount of NaOH in moles present in the diluted solution can be calculated using the formula:

moles of solute = Molarity × Volume of solution (in liters)

Here, the final volume of the diluted solution is 350 mL = 0.35 L, and the molarity of the diluted solution is 0.042 M. Therefore, the moles of NaOH in the diluted solution are:

moles of NaOH = 0.042 M × 0.35 L = 0.0147 moles

This means that option a is correct.

To calculate the molarity of the stock solution, we can use the formula:

M1V1 = M2V2

where M1 and V1 are the molarity and volume of the stock solution, and M2 and V2 are the molarity and volume of the diluted solution. Rearranging this formula, we get:

M1 = M2 × V2 / V1

Plugging in the given values, we get:

M1 = 0.042 M × 0.35 L / 0.025 L = 0.588 M

Therefore, option b is correct.

Option c is not correct, as we just calculated that the molarity of the stock solution is 0.588 M, not 0.030 M.

Finally, option d is correct, as we calculated earlier that the diluted solution contains 0.0147 moles of NaOH.

the freezing point of a glucose solution is -10.3deg c. the density of the solution is 1.50 g/ml. what is the molarity of the glucose solution? (mw of glucose

Answers

The molarity of the glucose solution is 8.30 mol/L.

Molarity calculation

To solve this problem, we need to use the freezing point depression equation:

ΔT = Kf * m

Where ΔT is the change in freezing point, Kf is the freezing point depression constant for the solvent (in this case, water), and m is the molality of the solute (in this case, glucose).

We know that the freezing point depression is 0 - (-10.3) = 10.3°C. The freezing point depression constant for water is 1.86 °C/m, so we can plug in these values to solve for the molality:

10.3°C = 1.86°C/m * m

m = 5.53 mol/kg

Now we need to convert molality to molarity. We know that the density of the solution is 1.50 g/ml, which means that 1 L of solution has a mass of 1500 g. Since the molar mass of glucose is 180.16 g/mol, we can calculate the number of moles of glucose in 1 L of solution:

5.53 mol/kg * 1.50 kg/L = 8.30 mol/L

Therefore, the molarity of the glucose solution is 8.30 M.

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The percentage composition of an organic acid is found to be 39. 9% C, 6. 7% H, and 53. 4% O. The molar mass for the composition is 60. 0g/mol. What is the molecular formula

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The molecular formula of the organic acid is C₂H₄O₄.

Assuming we have a 100 gram sample of the organic acid, we can calculate the masses of carbon, hydrogen, and oxygen present in the sample as follows:

Mass of C = 39.9 g

Mass of H = 6.7 g

Mass of O = 53.4 g

Next, we can convert these masses to moles using the atomic masses of each element,

Moles of C = 39.9 g / 12.01 g/mol = 3.32 mol

Moles of H = 6.7 g / 1.01 g/mol = 6.63 mol

Moles of O = 53.4 g / 16.00 g/mol = 3.34 mol

We then divide each mole value by the smallest mole value to get the simplest whole-number ratio of atoms,

Moles of C / Moles of O = 3.32 mol / 3.34 mol = 0.993

Moles of H / Moles of O = 6.63 mol / 3.34 mol = 1.98

Rounding these ratios to the nearest whole number gives us the empirical formula of the organic acid, which is C₁H₂O₂.

To find the molecular formula, we need to know the molar mass of the compound. We are given that the molar mass of the composition is 60.0 g/mol. The empirical formula C₁H₂O₂ has a molar mass of approximately 45.0 g/mol (1 × 12.01 g/mol for C, 2 × 1.01 g/mol for H, and 2 × 16.00 g/mol for O). To determine the molecular formula, we divide the molar mass of the compound by the molar mass of the empirical formula and round to the nearest whole number.

Molecular formula = (Molar mass of composition) / (Molar mass of empirical formula)

Molecular formula = 60.0 g/mol / 45.0 g/mol

Molecular formula = 1.33

Rounding this value to the nearest whole number, we get a molecular formula of C₂H₄O₄.

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1. in this experiment, if the carboxylic acid is benzoic acid, how many moles of benzoic acid are present (assume an equal portion of each component)? how many moles of sodium bicarbonate are contained in 1 ml of a saturated aqueous sodium bicarbonate? is the amount of sodium bicarbonate sufficient to react with all the benzoic acid?

Answers

In this experiment, if the carboxylic acid is benzoic acid, there would be 1 mole of benzoic acid present, and 1 ml of saturated aqueous sodium bicarbonate would contain 1 mole of sodium bicarbonate.

The amount of sodium bicarbonate is therefore sufficient to react with all the benzoic acid. The reaction between benzoic acid and sodium bicarbonate produces a salt, benzoate, and water.

In this experiment, if the carboxylic acid is benzoic acid, there would be 1 mole of benzoic acid present. Since the reaction involves an equal amount of each component, there would also be 1 mole of sodium bicarbonate.

1 ml of saturated aqueous sodium bicarbonate would contain 1 mole of sodium bicarbonate. Therefore, the amount of sodium bicarbonate is sufficient to react with all the benzoic acid.

Carboxylic acids, such as benzoic acid, are compounds with a carboxyl group attached to an alkyl or aryl group. Benzoic acid is an example of a carboxylic acid and is composed of C7H6O2.

Sodium bicarbonate is a salt composed of sodium and bicarbonate ions (NaHCO3).

In an acid-base reaction between a carboxylic acid and a bicarbonate salt, the carboxylic acid donates a proton to the bicarbonate ion, forming a water molecule and a carbonate ion.

The reaction between benzoic acid and sodium bicarbonate is: C7H6O2 + NaHCO3 → C7H5O3- + H2O + Na+.

When 1 mole of benzoic acid reacts with 1 mole of sodium bicarbonate, all of the benzoic acid is consumed and the sodium bicarbonate is also completely consumed.

The reaction results in the formation of a salt, benzoate, and water.

The reaction between an acid and a bicarbonate salt is a type of neutralization reaction, since the proton from the acid is neutralized by the bicarbonate ion.


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How much water, in grams, is needed to create 303 grams of hydrogen phosp better know as phosphoric acid?

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To create 303 grams of hydrogen phosphoric acid, we need 246 grams of water. Phosphoric acid is a type of acid that is commonly used in the production of fertilizers, detergents, and other chemicals.

Phosphoric acid is also used in the food industry as a food additive. The molecular formula for phosphoric acid is H3PO4. It is a triprotic acid, meaning it can donate up to three hydrogen ions in solution. The balanced chemical equation for the reaction of water with phosphoric acid is as follows:H3PO4 + H2O → H3O+ + H2PO4-If we examine this equation, we can see that one mole of phosphoric acid reacts with one mole of water. The molar mass of phosphoric acid is 98 g/mol. Therefore, to create 98 grams of phosphoric acid, we would need 18 grams of water (which is one mole of water).

We are given that we need to create 303 grams of phosphoric acid. Therefore, we can use the following proportion to determine how much water we need: 98 g of phosphoric acid is to 18 g of water as 303 g of phosphoric acid is to x g of water Solving for x, we get: x = (18 g of water/98 g of phosphoric acid) * 303 g of phosphoric acid x = 55.173 grams of water

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using the results from part a and part b calculate the enthalpy change of caco3 and water using hess' law
[A] CaCO3(s) + 2 HCl(aq) → CaCl2(aq) + CO2(g) + H2O(1) [B] Ca(OH)2(s) + 2 HCl(aq) → CaCl2(aq) + 2 H2O(0)

Answers

The enthalpy change of CaCO3 and water is -1052 kJ/mol. (using Hess' law)

Enthalpy Change is the amount of heat energy released or absorbed during a chemical reaction. Using the results from part an and part b, the enthalpy change of CaCO3 and water can be calculated using Hess' law.  Here's how to do it:CaCO3(s) + 2 HCl(aq) → CaCl2(aq) + CO2(g) + H2O(1).............. (1).                                                                                  Ca(OH)2(s) + 2 HCl(aq) → CaCl2(aq) + 2 H2O(0).................. (2)

The enthalpy change of equation (1) is the enthalpy of formation of CaCO3.

The enthalpy change of equation (2) is the enthalpy of neutralization of Ca(OH)2 with HCl.

The enthalpy change of the reaction of CaCO3 with two moles of HCl can be calculated by combining equations (1) and (2).In equation (1), one mole of CaCO3 produces one mole of H2O, while in equation (2), one mole of Ca(OH)2 produces two moles of H2O.

So, we need to multiply equation (1) by 2 to make the number of moles of H2O equal:

2 CaCO3(s) + 4 HCl(aq) → 2 CaCl2(aq) + 2 CO2(g) + 2 H2O(1)....... (3)

Now, we can subtract equation (2) from equation (3) to obtain the enthalpy change of CaCO3 and water:

2 CaCO3(s) + 2 H2O(1) → 2 Ca(OH)2(s) + 2 CO2(g).

(ΔH = ΔH3 - ΔH2 = (-1184) - (-132) = -1052 kJ/mol)

Therefore, the enthalpy change of CaCO3 and water is -1052 kJ/mol. (using Hess' law)

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which of the following aqueous solutions will have the lowest % ionization? 1.0 m hf 1.0 m hcl 1.0 m naoh 0.5 m ba(oh)2 1.0 m sr(oh)2

Answers

The aqueous solution with the lowest % ionization will be 0.5 m Ba(OH)2. This is because the dissociation of Ba(OH)2 is the least among all the solutions, making it the least ionized.


Explanation: The 0.5 M Ba(OH)2 aqueous solution will have the lowest % ionization.Based on the given options, the lowest % ionization will be observed in 0.5 M Ba(OH)2 aqueous solution. Here's why:Acids and bases are classified as weak or strong depending on the extent to which they ionize when dissolved in water. The stronger the acid or base, the greater the degree of ionization when it dissolves in water. This is because strong acids and bases are nearly completely ionized in solution. Aqueous solution of HF and HCl:HF is a weak acid, and HCl is a strong acid. As a result, HCl is more acidic than HF, with a greater degree of ionization. NaOH aqueous solution:NaOH is a strong base, which means that it completely ionizes in water. Ba(OH)2 and Sr(OH)2 aqueous solutions:Ba(OH)2 and Sr(OH)2 are both strong bases, but the degree of ionization depends on their concentration. A solution of 1 M Ba(OH)2 is 50% ionized, whereas a solution of 1 M Sr(OH)2 is 80% ionized. So, among the given options, the 0.5 M Ba(OH)2 aqueous solution will have the lowest % ionization.

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predict which of the following 0.1m solutions would have the lowest freezing point: mg(cl)2, catechin, or sucrose. explain your reasoning.

Answers

The freezing point of a 0.1m solution is determined by its solute concentration, and the type of solute affects the freezing point and it will be Catechin.

The lowest freezing point will be found in the solution with the lowest solute concentration.

In this case, catechin has the lowest solute concentration of 0.001 mol/L, so it will have the lowest freezing point.

The freezing point of a solution is also affected by the type of solute present.

Magnesium chloride (MgCl2) and sucrose both have high molecular weights, and therefore will decrease the freezing point more than catechin. Therefore, catechin will still have the lowest freezing point.

The freezing point of a solution can also be affected by the presence of electrolytes.

Magnesium chloride is an electrolyte, which means it will dissociate in water and lower the freezing point more than catechin or sucrose. Therefore, catechin still has the lowest freezing point.

In summary, catechin has the lowest freezing point of the three solutions (MgCl2, catechin, and sucrose) because it has the lowest solute concentration and does not contain any electrolytes.

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please help the image is attached!!!​

Answers

Answer:

0.6096

Explanation:

*formula for moles= mass/molormass(RFM)

Molarmass= (28×1)+(19×4)= 104

63.4/104= 0.60961

what will you use to prepare the calibration curve in this project? group of answer choices a solvent blank. a series of solutions with the exact same analyte concentration. a series of solutions with various unknown analyte concentrations. a series of solutions with a range of precisely known analyte concentrations.

Answers

A  series of solutions with a range of precisely known analyte concentrations. Option D

What is a calibration curve?

A calibration curve is a graphical representation of the relationship between the concentration or amount of a substance, and a signal or measurement obtained from an analytical instrument or assay. The calibration curve is constructed by measuring the signal or response of the instrument or assay at different known concentrations or amounts of the substance, and plotting these values on a graph.

The resulting curve is then used to determine the concentration or amount of the substance in an unknown sample by measuring its signal or response and comparing it to the calibration curve.

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the precise amount of air required for the complete combustion of a hydrocarbon can be calculated by considering the stoichiometric conversion of the hydrocarbon to co2 and h2o. determine the stoichiometric air-fuel ratios for combustion of cyclohexane, cyclohexene, and benzene.

Answers

The stoichiometric air-fuel ratios for the combustion of cyclohexane, cyclohexene, and benzene are 8:1, 9:1, and 17:1, respectively.

The stoichiometric air-fuel ratio for combustion of hydrocarbons, such as cyclohexane, cyclohexene, and benzene, is the amount of air necessary for complete combustion of the hydrocarbon.

This can be determined by considering the stoichiometric conversion of the hydrocarbon to carbon dioxide (CO2) and water (H2O).

For cyclohexane, the stoichiometric conversion is 8 moles of air to 1 mole of cyclohexane. This means the stoichiometric air-fuel ratio is 8:1.

Similarly, for cyclohexene, the stoichiometric conversion is 9 moles of air to 1 mole of cyclohexene.

Therefore, the stoichiometric air-fuel ratio for cyclohexene is 9:1. For benzene, the stoichiometric conversion is 17 moles of air to 1 mole of benzene. This yields a stoichiometric air-fuel ratio of 17:1.

In summary, the stoichiometric air-fuel ratios for the combustion of cyclohexane, cyclohexene, and benzene are 8:1, 9:1, and 17:1, respectively.

These ratios are important to consider when performing combustion calculations and are necessary for complete combustion of hydrocarbons.

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which of the following is false regarding reaction mechanisms? select the correct answer below: reaction mechanisms with more than one step do not always contain intermediates. elementary reactions occur exactly as written. reactions do not need to involve intermediates. intermediates are produced in one step and consumed in a subsequent step.

Answers



False statement is Reaction mechanisms with more than one step do not always contain intermediates.

In a reaction mechanism, an intermediate is an unstable substance formed when reactants are partially transformed into products.

In some reactions with more than one step, the intermediates may be left out of the reaction mechanism, which is why the statement is false.

An elementary reaction is one that occurs in a single, defined step and does not involve intermediates. Elementary reactions occur exactly as written, and the intermediate states do not need to be shown.

Reactions may or may not involve intermediates. If a reaction involves an intermediate, the intermediate is usually produced in one step and consumed in a subsequent step.

The reaction mechanism must include the intermediate steps in order to fully explain the reaction process.

The statement, "Reaction mechanisms with more than one step do not always contain intermediates" is false.

Elementary reactions occur exactly as written and do not involve intermediates, while reactions that involve intermediates must include intermediate steps in the reaction mechanism.

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if no activation energy were required to break down sucrose (table sugar), would you be able to store it in a sugar bowl?

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If no activation energy were required to break down sucrose (table sugar), it would not be possible to store it in a sugar bowl.

Activation energy is the minimum energy required for a reaction to occur. It is also required for the decomposition of sucrose, which is a disaccharide consisting of glucose and fructose units. If there were no activation energy required to break down sucrose, it would not be possible to store it in a sugar bowl.

This is because it would decompose quickly into its constituent monosaccharides, glucose, and fructose.

As a result, it would become less sweet and less tasty. The reaction rate would be increased, resulting in a rapid change in the chemical structure of sucrose.

This would imply that it is difficult to store it in a sugar bowl.

Hence, if no activation energy were required to break down sucrose, it would not be possible to store it in a sugar bowl.

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old ammunition or fireworks, lithium-sulfur batteries, wastes containing cyanides or sulfides, and chlorine bleach and ammonia are examples of which type of hazardous waste?

Answers

These are all examples of chemical hazardous waste. Chemical hazardous waste is waste that is flammable, reactive, corrosive, or toxic. It can include things like unused pesticides, paint, cleaning products, or batteries.

Old ammunition or fireworks, lithium-sulfur batteries, wastes containing cyanides or sulfides, and chlorine bleach and ammonia are examples of Household hazardous waste.What is hazardous waste?Hazardous waste is a waste material that is harmful to human health or the environment. Every year, households and businesses generate hazardous waste in various forms. Because hazardous waste may be flammable, poisonous, reactive, or corrosive, it requires special disposal procedures. Hazardous wastes must be properly disposed of to safeguard human health and the environment.Household hazardous waste (HHW) is the type of waste that can be found in a typical home. This waste is produced by households when they use products that contain harmful chemicals. Old ammunition or fireworks, lithium-sulfur batteries, wastes containing cyanides or sulfides, and chlorine bleach and ammonia are examples of household hazardous waste.

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Which of the following best explains why doubling the temperature of a gas in a closed container caused the pressure to be doubled?

Answers

The correct option is: Increasing the temperature increases the frequency and force of collisions between gas molecules and the container walls, causing the pressure to increase.

What happens when temperature of a gas increased

When the temperature of a gas in a closed container is increased, the gas molecules gain kinetic energy and move faster, colliding with the container walls more frequently and with greater force.

According to the kinetic theory of gases, the pressure of a gas is directly proportional to the frequency and force of collisions between gas molecules and the container walls.

Therefore, doubling the temperature of a gas in a closed container would also double the pressure of the gas.

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what is the expected absorbance of a standard solution made by dissolving 0.0070 mol of nicl2 * 6h20 in water to make 100 ml of solution?

Answers

The expected absorbance of a standard solution made by dissolving 0.0070 mol of NiCl2 · 6H2O in water to make 100 ml of solution is 0.227.

Absorbance is a measure of the quantity of light that passes through a sample relative to the quantity of light that passes through a blank sample.

The sample absorbance is determined by the sample's concentration, thickness, and absorbing properties of the solution.

In order to calculate the expected absorbance of a standard solution made by dissolving 0.0070 mol of NiCl2 · 6H2O in water to make 100 ml of solution, we need to use the Beer-Lambert Law.

It states that the absorbance of a solution is directly proportional to the concentration of the solution and the length of the path that the light has to travel through the solution.

So, A = εlc where A = absorbanceε = molar extinction coefficient l = path length c = concentration Since the path length and molar extinction coefficient are constant, the absorbance is proportional to the concentration.

So, A1/A2 = C1/C2

Where, A1 = absorbance of the standard solutionC1 = concentration of the standard solution

A2 = absorbance of the unknown solutionC2 = concentration of the unknown solution Rearranging the formula we get, C2 = C1(A2/A1)

Given that the concentration of the standard solution is 0.0070 mol/L and the path length is 1 cm.

The molar extinction coefficient for NiCl2·6H2O is 4.76 × 10^3 L/mol·cm. Substituting these values in the formula we get, C2 = 0.0070 mol/L × (0.380/1.660) = 0.0016 mol/L

Again, using the Beer-Lambert law we can find the expected absorbance of the unknown solution, where A = εlc.A = 4.76 × 10^3 L/mol·cm × 1 cm × 0.0016 mol/L = 7.62.

The expected absorbance of a standard solution made by dissolving 0.0070 mol of NiCl2 · 6H2O in water to make 100 ml of solution is 0.227.

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what volume of 0.125 m nitric acid is required to completely neutralize 25.0 ml of 0.100 m barium hydroxide?

Answers

The volume of 0.125 M nitric acid that is required to completely neutralize 25.0 mL of 0.100 M barium hydroxide is 31.25 mL.

This can be calculated using the formula:

Molarity of acid x Volume of acid = Molarity of base x Volume of base

Given:

Molarity of nitric acid = 0.125 M

Volume of nitric acid = ?

Molarity of barium hydroxide = 0.100 M

Volume of barium hydroxide = 25.0 mL = 0.025 L

Using the formula:

0.125 V = 0.100 × 0.025

V = (0.100 × 0.025) / 0.125

V = 0.020 L or 20 mL

Therefore, the volume of 0.125 M nitric acid that is required to completely neutralize 25.0 mL of 0.100 M barium hydroxide is 31.25 mL.

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for a given chemical system, do the equilibrium constant (k) and the reaction quotient (q) differ or are they the same?

Answers

For a given chemical system, the equilibrium constant (K) and the reaction quotient (Q) are not the same, but rather they differ.

What is an Equilibrium Constant (K)?

The equilibrium constant (K) is a ratio of equilibrium concentrations, and it is a measure of how far a chemical reaction has progressed at a certain temperature. K is a ratio of the products' concentration to the reactants' concentration, each raised to the power of their respective stoichiometric coefficients. The value of K is temperature-dependent.

What is the Reaction Quotient (Q)?

The reaction quotient, Q, on the other hand, is a ratio of concentrations that are not at equilibrium but instead have been taken at any point in time during the reaction's progress. The reaction quotient is used to determine whether a system is at equilibrium, will proceed to the left or the right to reach equilibrium, or will remain unchanged. The value of Q, like the equilibrium constant, is temperature-dependent.


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If I started with 50 moles of N2OOH, how many moles of H2O2 would I end up with

Answers

Answer: Not possible

Explanation:

It's not possible to determine how many moles of H2O2 you would end up with based on the information given.

The reason for this is that we don't know what is happening to the N2OOH in this scenario. Depending on the conditions and reaction occurring, the N2OOH could potentially break down into one or more different compounds, or it could react with another substance to form a new compound. Without this information, we cannot determine the amount of H2O2 that would result.

Explanation:

The chemical equation for the decomposition of N2OOH (dinitrogen trioxide) is:

N2OOH → 2 H2O2

This equation shows that one mole of N2OOH decomposes to produce two moles of H2O2.

If you start with 50 moles of N2OOH, you can calculate the number of moles of H2O2 produced by multiplying the number of moles of N2OOH by the stoichiometric coefficient of H2O2 in the balanced equation.

So,

Number of moles of H2O2 = 2 x 50 moles of N2OOH

= 100 moles of H2O2

Therefore, starting with 50 moles of N2OOH will produce 100 moles of H2O2 after complete decomposition

why is there no one method to evaluate ml models? everyone has there own way to come up with an accuracy percentage...

Answers

There is no one method to evaluate machine learning (ML) models because everyone has their own way of calculating the accuracy percentage.

Machine learning is an ever-evolving field that requires a lot of data analysis and knowledge of mathematical and statistical principles. Evaluating machine learning models is a complex process, and there is no one-size-fits-all solution. There are various ways to evaluate the accuracy of ML models, and the best approach depends on the model's purpose, features, and size.

The following are some of the challenges of evaluating machine learning models:

Interpretability: One of the most significant challenges is interpretability. Many ML models are not explainable, making it difficult to interpret their performance metrics. This makes it challenging to identify any issues with the model and make appropriate adjustments.

Data quality: Machine learning models are only as good as the data they are trained on. It is essential to ensure that the data used to train and evaluate the model is of high quality and representative of the real-world environment.

Model selection: Choosing the right model for a particular task is another challenge. The model selection process depends on the data, available resources, and the goal of the project.

Hence, Several metrics can be used to evaluate the accuracy of ML models, including accuracy, precision, recall, F1 score, and AUC-ROC. Machine learning practitioners usually choose the best metric for a particular task or model depending on the data they have.

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for the next several questions, use the following information: a 2.00 g sample of ammonia (nh3 ) reactants with 4.00 g of oxygen to form nitrogen monoxide and water. all of the reactants and products are gases. do not forget about diatomic molecules.

Answers

Since we are given the reactants and products in a chemical reaction, we can write the balanced chemical equation as:

4 NH3 + 5 O2 → 4 NO + 6 H2O

From the balanced equation, we can see that 4 moles of NH3 react with 5 moles of O2 to form 4 moles of NO and 6 moles of H2O.

To solve the following questions, we can use the stoichiometry of the balanced chemical equation.

How many moles of NH3 are in the sample?

The molar mass of NH3 is 17.03 g/mol, so the number of moles of NH3 in the sample is:

2.00 g / 17.03 g/mol = 0.1173 mol NH3

How many moles of O2 are in excess?

We can first calculate the number of moles of O2 required to react completely with NH3. From the balanced equation, we know that 4 moles of NH3 react with 5 moles of O2, so the number of moles of O2 required is:

0.1173 mol NH3 × (5 mol O2 / 4 mol NH3) = 0.1466 mol O2

The actual amount of O2 used is 4.00 g / 32.00 g/mol = 0.125 mol O2, so the number of moles of O2 in excess is:

0.125 mol O2 - 0.1466 mol O2 = -0.0216 mol O2

Since the value is negative, it means that O2 is the limiting reactant, and NH3 is in excess.

How many moles of H2O are produced?

From the balanced equation, we know that for every 4 moles of NH3 reacted, 6 moles of H2O are produced. Therefore, the number of moles of H2O produced is:

0.1173 mol NH3 × (6 mol H2O / 4 mol NH3) = 0.1760 mol H2O

What is the mass of NO produced?

The molar mass of NO is 30.01 g/mol, so the mass of NO produced is:

0.1173 mol NH3 × (4 mol NO / 4 mol NH3) × 30.01 g/mol = 3.52 g NO

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whit is the molarity of a NH3 solution if it has a density of 0.982g/mL

Answers

The molarity of the NH3 solution is 0.0576 M.

How to determine the molarity of a NH3 solution

We can use the following steps to calculate the molarity of the NH3 solution:

Determine the mass of 1 mL of the NH3 solution using the given density:

mass of 1 mL of NH3 solution = density x volume of 1 mL

mass of 1 mL of NH3 solution = 0.982 g/mL x 1 mL = 0.982 g

Determine the number of moles of NH3 in 1 mL of the solution using the molar mass of NH3 (17.03 g/mol):

moles of NH3 in 1 mL of solution = mass of NH3 / molar mass of NH3

moles of NH3 in 1 mL of solution = 0.982 g / 17.03 g/mol = 0.0576 mol

Calculate the molarity of the NH3 solution using the number of moles of NH3 in 1 liter of the solution (1000 mL):

molarity of NH3 solution = moles of NH3 / volume of solution in liters

molarity of NH3 solution = 0.0576 mol / 1 L = 0.0576 M

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which one of the following amino acids r groups (a.k.a. side chain) is most likely to participate in hydrogen bonding with water? group of answer choices asparagine alanine leucine phenylalanine valine

Answers

The amino acid most likely to participate in hydrogen bonding with water is Asparagine.

Asparagine has an amide group (–CONH2) as its side chain, which is polar and can form hydrogen bonds with water.

Hydrogen bonds are a type of intermolecular force that occurs when a hydrogen atom of one molecule is attracted to an electronegative atom (usually oxygen or nitrogen) of another molecule.

In water, these hydrogen bonds help to stabilize the molecules and increase its boiling point.

The other amino acid side chains are not likely to form hydrogen bonds with water. Alanine has a methyl group (–CH3), which is non-polar and not able to form hydrogen bonds.

Leucine and valine both have an isopropyl group (–CH(CH3)2), which is also non-polar. Finally, Phenylalanine has a phenyl group (–C6H5), which is slightly polar, but not to the same extent as the amide group of Asparagine.

In conclusion, Asparagine is the amino acid side chain most likely to form hydrogen bonds with water. The other amino acid side chains are not able to form hydrogen bonds due to their non-polar nature.

Hydrogen bonds between Asparagine and water help to stabilize the molecules and increase its boiling point.

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Which of the following weak acids would cause the greatest decrease in pH ? Acid(a):H2 S Acid (b): H2Se Because these are in/with the greater the the weaker the bond to H. The acid that will cause the greatest decrease in pH will be the with the which is Which of the following weak acids would have the smallest pKa ? Acid (a): H2 S Acid (b): H3P Because these are in/with , the greater the the weaker the bond to H. The acid with the smallest p Ka will be the with the which is

Answers

1. The acid that will cause the greatest decrease in pH will be H₂Se

2. The acid with the smallest pKa is Acid (b): H₃P.

What is pH?

The H+ ion concentration's negative constant is known as pH. As a result, the meaning of pH is validated as the strength of hydrogen.

1. The acid that will cause the greatest decrease in pH will be the one with the smallest pKa. This is because the smaller the pKa, the stronger the acid. A stronger acid will release more H⁺ ions when dissolved in water and thus cause a greater decrease in pH. So, the correct option is b. H₂Se will have greatest decrease in pH.

2. The acid with the smallest pKa will be the one with the strongest bond to H. This is because the stronger the bond to H, the weaker the acid. A weaker acid will not release as many H⁺ ions when dissolved in water and thus have a smaller effect on pH. Therefore, the acid with the smallest pKa is Acid (b): H₃P.

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