Question 1

For the endothermic reaction $$\mathrm{CH_4$(g) + 2\ H_2S(g) \leftrightarrow CS_2$(g) + 4\ H_2$(g)}$$, which of the following changes will shift the equilibrium to the right (toward products)?

Accepted Answer

Removing $$\mathrm{CS_2$}$$ gas

Question 2

Given the equilibrium $$\mathrm{NH_4HS(s) \leftrightarrow NH_3$(g) + H_2S(g)} at$$ $$24^\circ\mathrm{C}$$, if excess solid $$\mathrm{NH_4HS} is $$present and $$0.00750$$ mol of $$\mathrm{NH_3$}$$ and $$0.00750$$ mol of $$\mathrm{H_2S}$$ are mixed in a $$1.0 L $$container, what will happen to the system?

Accepted Answer

The system is already at equilibrium and no shift will occur

Question 3

For the equilibrium $$\mathrm{$$CaCO_3$$(s) \leftrightarrow CaO(s) + CO_2$(g)} at$$ $$800\ \mathrm{K}$$, if the equilibrium pressure of $$\mathrm{CO_2$} is$$ $$0.220\ \mathrm{atm}$$, what is the value of $$K_p$$?

Accepted Answer

$$K_p = 0.220$$

Question 4

For the equilibrium $$\mathrm{3Fe(s) + 4H_2O(g) \leftrightarrow Fe_3O_4(s) + 4H_2(g)} at$$ $$900^\circ\mathrm{C}$$, $$K_c = 1.5$$, if $$0.050$$ mol $$\mathrm{H_2O}$$ and excess $$\mathrm{Fe}$$ are placed in a $$1.0 L $$container, what is the equilibrium concentration of $$\mathrm{H_2$}$$?

Accepted Answer

$$[\mathrm{H_2$}] = 0.030\ \mathrm{mol/L}$$

Question 5

Which of the following stresses will increase the concentration of $$\mathrm{Fe$$^{2+}$$} in a $$saturated solution of $$\mathrm{FeS(s)}$$?

Accepted Answer

Adding water

Question 6

In the equilibrium $$\mathrm{2Ag^+ + S$$^{2-}$$ \leftrightarrow Ag_2S(s)}$$, what will happen to the concentration of $$\mathrm{Ag^+} if$$ $$\mathrm{Na_2S} is $$added to the solution?

Accepted Answer

It will decrease

Question 7

For the equilibrium $$\mathrm{HS^-(aq) \leftrightarrow H^+(aq) + S$$^{2-}$$(aq)}$$, what effect does adding $$\mathrm{HCl}$$ have on the position of equilibrium?

Accepted Answer

Shifts equilibrium to the left

Question 8

A student adds $$\mathrm{$$AgNO_3$$} to a $$solution saturated with $$\mathrm{FeS}$$, which of the following will occur?

Accepted Answer

Precipitation of $$\mathrm{Ag_2S}$$ and decrease in $$[Fe$$^{2+}$$]$$

Question 9

Hydrogen iodide gas decomposes according to $$\mathrm{2HI(g) \leftrightarrow H_2$(g) + I_2$(g)}. If$$ $$0.200$$ mol $$\mathrm{HI} is $$placed in a $$1.0 L $$container and at equilibrium $$0.040$$ mol $$\mathrm{I_2$} is $$present, what is the equilibrium constant $$K_c$$?

Accepted Answer

$$K_c = 0.067$$

Question 10

Which of the following will NOT affect the equilibrium position of a chemical reaction?

Accepted Answer

Adding a catalyst

Question 11

For the equilibrium $$\mathrm{FeS(s) \leftrightarrow Fe$$^{2+}$$(aq) + S$$^{2-}$$(aq)}$$, what will happen to $$[S$$^{2-}$$] if$$ $$\mathrm{HCl} is $$added?

Accepted Answer

$$[S$$^{2-}$$]$$ will decrease

Question 12

In the reaction $$\mathrm{CH_4$(g) + 2H_2S(g) \leftrightarrow CS_2$(g) + 4H_2(g)}$$, what is the effect of increasing the pressure on the equilibrium?

Accepted Answer

Shifts equilibrium to the left

Question 13

For the equilibrium $$\mathrm{HS^-(aq) \leftrightarrow H^+(aq) + S$$^{2-}$$(aq)}$$, what will happen to $$[HS^-] if$$ $$\mathrm{NaOH} is $$added?

Accepted Answer

$$[HS^-]$$ will increase

Question 14

A system at equilibrium is disturbed by removing some product. What is the expected response according to Le Chatelier's Principle?

Accepted Answer

The system will shift to produce more product

Question 15

For the equilibrium $$\mathrm{2HI(g) \leftrightarrow H_2$(g) + I_2$(g)}$$, which of the following will increase the value of the equilibrium constant $$K$$?

Accepted Answer

Increasing the temperature if the reaction is endothermic

Question 16

In a saturated solution of $$\mathrm{FeS}$$, which of the following will cause precipitation of $$\mathrm{FeS}$$?

Accepted Answer

Adding $$\mathrm{HCl}$$

Question 17

For the equilibrium $$\mathrm{$$CaCO_3$$(s) \leftrightarrow CaO(s) + CO_2$(g)}$$, what will happen if the volume of the container is decreased?

Accepted Answer

No effect on equilibrium position

Question 18

Which of the following best describes the effect of adding a catalyst to a system at equilibrium?

Accepted Answer

Speeds up the attainment of equilibrium without changing the equilibrium position

Equilibrium and Le Chatelier's Principle: General Chemistry Study Notes

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