A 0.9000 g sample of a mixture of NaCl and KCl is dissolved in water, and the solution is then treated with an excess of AgNO₃ to yield 1.923 g of AgCl. Calculate the percent by mass of each compound in the mixture.

____% mass of NaCl

____% mass of KCl

a) Calculate the change in entropy on heating an ideal gas from 300K to 500K at constant pressure.

b) Calculate the change in entropy on heating an ideal gas from 300K to 500K at constant volume.

c) why these answers are different.

Please explain each steps.

What additives may be used to prevent acid catalyzed hydrolysis of drugs containing ester moieties in drug formulations?

Please answer:
Discuss how many anions are able to contaminate groundwater.

Menthol is a crystalline substance with a peppermint taste and odor. When 1.19 g of menthol is dissolved in 25.0 g of cyclohexane, the freezing point of the solution is lowered by 6.34 ∘ C. Look up the freezing point and K f constant for cyclohexane in the Colligative Constants table. Calculate the molar mass of menthol.

Imagine two solutions with the same concentration and the same boiling point, but one has ethanol as the solvent and the other has carbon tetrachloride as the solvent. Determine that molal concentration, m (or b),m (or b), and boiling point, Tb.Tb.

m=

Tb=

Firefly luciferase is the enzyme that allows fireflies to illuminate their abdomens. Because this light generation is an ATP-requiring reaction, firefly luciferase can be used to test for the presence of ATP. In this way, luciferase can test for the presence of life. The coupled reactions are

1.2.luciferin+O2ATP⇌⇌oxyluciferin+lightAMP+PPiΔG∘=−31.6 kJ/mol

If the overall ΔG∘ of the coupled reaction is -5.50 kJ/mol , what is the equilibrium constant, K, of the first reaction at 23 ∘C ?

This is a physical chemistry question.

Write down for yourself the secular determinant for the hypothetical molecule linear H₃ making the Huckel approximation, using the 1s atomic orbitals from each atom as the basis set. Given that α=-2.00 eV and β= -2 eV, what is the total electronic energy in eV?

(I already have part A but still still include it anyways so you can use its data to solve for parts B and C.

Chemical energy is released or absorbed from reactions in various forms. The most easily measurable form of energy comes in the form of heat, or enthalpy. The enthalpy of a reaction can be calculated from the heats of formation of the substances involved in the reaction:

ΔH∘rxn=ΔH∘f(products)−ΔH∘f(reactants)

Entropy change, ΔS∘, is a measure of the number of energetically equivalent microstates introduced into the system during the reaction. The degree of spontaneity of a reaction is represented by the Gibbs free energy, ΔG∘. The Gibbs free energy depends on both the enthalpy and entropy changes that take place during the reaction:

ΔG∘=ΔH∘−TΔS∘

where T is standard temperature, 298 K.

Part A

Part complete

Calculate the standard enthalpy change for the reaction

2A+B⇌2C+2D

where the heats of formation are given in the following table:

Express your answer in kilojoules.

ΔH∘rxn = 315 kJ  

Part B

For the reaction given in Part A, how much heat is absorbed when 3.30 mol of A reacts?

Express your answer numerically in kilojoules.

Part C

For the reaction given in Part A, ΔS∘rxn is 41.0 J/K . What is the standard Gibbs free energy of the reaction, ΔG∘rxn?

Express your answer numerically in kilojoules.

According to the ideal gas law, a 9.776 mol sample of xenon gas in a 0.8177 L container at 499.7 K should exert a pressure of 490.2 atm. By what percent does the pressure calculated using the van der Waals' equation differ from the ideal pressure? For Xe gas, a = 4.194 L2atm/mol2 and b = 5.105×10-2 L/mol.

HCl + NH3 ---> NH4Cl

Calculate the molar enthalpy of the reaction in terms of kJ per mol of NH4Cl

Can you tell me why in some experiments (such as biodiesel production) do we need to test the cloud point and pour point? What is the purpose?