Chemistry Answers

The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to completion (least to greatest tendency).

1. 2NOCl ↔ 2NO + Cl₂ Kc = 1.7 x 10^-2

2. 2SO_3 ↔ 2SO₂ + O₂ Kc = 1.3 x 10^-5

3. 2NO_2 ↔ 2NO + O₂ Kc = 5.9 x 10^-5

1. 2 < 1 < 3
2. 3 < 1 < 2
3. 3 < 2 < 1
4. 1 < 2 < 3
5. 2 < 3 < 1

Which is the correct equilibrium constant expression for the following reaction?

Fe₂O₃(s) + 3H₂(g) ↔ 2Fe(s) + 3H₂O(g)

1. K_c = [Fe₂O₃] [H₂]³ / [Fe] ² [H₂O] ³
2. K_c = [Fe] [H₂O] / [Fe₂O₃] [H₂]
3. K_c = [H₂] / [H₂O]
4. K_c =  [H₂O]³  / [H₂]³
5. K_c = [Fe] ² [H₂O] ³ / [Fe₂O₃] [H₂]³

For the equilibrium reaction

2SO₂(g) + O₂(g) ↔2SO₃(g) (H° = -198 kJ) 

which one of the following factors would cause the equilibrium constant to increase?

1. Add SO₂ gas.
2. Decrease the temperature.
3. Add a catalyst.
4. None of the above.

The following reaction is at equilibrium at one atmosphere, in a closed container.

NaOH(s) + CO₂(g) ↔ NaHCO₃(s)

Which, if any, of the following actions will decrease the total amount of CO₂ gas present at equilibrium?

1.decreasing the volume of the container

2.removing half of the solid NaHCO₃

3.adding more solid NaOH

4.adding N₂ gas to double the pressure

5.None of the above.

Calculate the mass (in grams) of CO2 in a 2.0 L soft drink after the bottle is opened and equilibrates at 25 °C under a CO2 partial pressure of 3.0 x 10-4 atm. The Henry’s law constant for CO2 at this temperature is 3.4 x 10-2 mol/L.atm 

A solution of 0.640 g of epinephrine in 36.0 g of CCl4 elevates the boiling point by 0.490°C. Kb = 5.02 °C m -1 and Kf = 29.8 °C m -1 for CCl4. (a) What is the molality of the solution?

Ethyne gas combusts with oxygen gas according to the following reaction:

Calculate the volume, in mL of CO2 produced when  84.4 g of C2H2 react at 62.2 °C and 1.38 atm. (R = 0.0821 L atm/mol K)

2𝐶2𝐻2(𝑔)+5𝑂2(𝑔)⟶4𝐶𝑂2(𝑔)+𝐻2𝑂(𝑙)

(round to hundredth place)

Chemical property of Lanthanide similar due to

1. The soda cans used in this experiment are coated with a combination of paint and a protective polymer to protect the Aluminum from the acidic contents of soda. Describe how you could evaluate the total mass of the coating material on the can?
2. Would this technique be useful on a sample known to be made of pure Al? What about a sample of Al coated with a different metal such as Zinc?
3. A large water tank is used to equalize the level of liquid inside the buret and the liquid level outside the buret. If this step is skipped, how would the difference in volume affect the final mass of Al and your percent purity?
4. Zinc is also fairly reactive with HCl. Write a chemical equation and suggest a factor that would need to be considered for this experiment if the soda cans where made from Zinc?

What is the concentration of hydronium ions in a solution which is 0.5M with respect to nitrous acid and 0.65M with respect to sodium nitrite? Assume that sodium nitrite is completely ionized.