Name _ Chemical Equilibrium Class Date _ Chapter 19 Test 6 7 2 4 3 9 5 8 1 ___ 17 ___ 10 ___ 16 ___ 14 ___ 15 ___ 11 ___ 12 ___ 13 DIREaIONS: Write on the line at the right of each statement the letter preceding the word or expression that best completes the statement. 1. At equilibrium, (a) forward reaction rate is less than reverse reaction rate; (b) forward reaction rate is greater than reverse reaction rate; (c) forward reaction rate is equal to reverse reaction rate; (d) no reactions take place. 2. A reaction in which products can react to re-form reactants is said to be (a) at equilibrium; (b) reversible; (c) buffered; (d) impossible. 3. The chemical equilibrium expression for the equation L + 2M +=! 4N + 30 is K = (a) [N]4[0]3/[L][Mf; (b) [L][M]z/[N]4[0]3;(c) 4[N]3[0]/[L]2[M]; (d) [L]2[M]/4[N]3[0]. 4. A very high value of K indicates that (a) equilibrium is reached slowly; (b) products are favored; (c) reactants are favored; (d) equilibrium has been reached. 5. The numerical value of K for a system (a) can be calculated from information on molar masses; (b) can be calculated from information on heat of reaction; (c) can be calculated from information on chemical properties; (d) must be obtained experimentally. 6. What is the effect on concentrations if more CO(g) is added to the following equilibrium system: 2CO(g) + Oz(g) +=! 2COz(g)? (a) [COz] increases and [Oz] decreases (b) [COz] increases and [Oz] increases (c) [COz] decreases and [Oz] decreases (d) both [COz] and [Oz] remain the same 7. What is the effect on concentrations if the temperature of the equilibrium system CH30H(g) + 101kJ +=! CO(g) + 2Hz(g) is increased? (a) [CH30H] increases and [CO] decreases (b) [CH30H] decreases and [CO] increases (c) [CH30H] increases and [CO] increases (d) there'is no effect 8. Reaction systems that are in equilibrium may be made to run to completion (a) only if they are not reversible; (b) only if the temperature is low enough; (c) by application of LeChatelier's principle; (d) under no circumstances. 9. Reactions tend to run to completion if a product (a) has a high melting point; (b) is precipitated as a solid; (c) is a liquid; (d) is ionic. 10. The addition of sodium acetate to an acetic acid (HCzH30Z) solution (a) increases pH and lowers [H +]; (b) increases pH and raises [H +]; (c) decreases pH and lowers [H +]; (d) decreases pH and raises [H +]; 11. In the equilibrium system HCzH30Z(aq) + HzO(t) <=zH30+(aq) + CZH30Z(aq), which of the following is present in the highest concentration? (a) HCzH30Z(b) H30+ (c) CZH30Z (d) The concentrations of HCzH30Z, H30 +, and CZH30Z are all equal. 12. The equilibrium constant K for the ionization of acetic acid HCzH30Z(aq) + HzO(t) <=Z H30+(aq) + CZH30Z (aq) is equal to (a) [H30+][CzH30z]; (b) [H30+][CzH30Z]/[HCzH30Z][HzOI; (c) [H30+][CzH30zl/[HCzH30zl; (d) [HCzH30z]l[H30+][CzH30zl. 13. How do Ka values for weak and strong acids compare? (a) Ka (weak) = Ka (strong) (b) Ka (weak) < Ka (strong) (c) Ka (weak) > Ka (strong) (d) Ka is not defined for weak acids. 14. The equation for the ionization of water is (a) 2HzO(t) <=Z H30+(aq) + OH-(aq); (b) 2HzO(t) <=Z H30-(aq) + OH+(aq); (c) 2HzO(t) <=Z 2Hz(aq) + Oz(aq); (d) HzO(t) <=Z H-(aq) + OH+(aq). 15. The value of the ion-product constantfor water is (a) 0; (b) 10 - 14;(c) 10 - 7; (d) 55.4. 16. Addition of the salt of a weak acid to a solution of the weak acid (a) lowers the concentration of the nonionized acid and of H30 +; (b) lowers the concentration of the non ionized acid and raises the concentration of the H30 +; (c) raises the concentration of the non ionized acid and of H30 +; (d) raises the concentration of the non ionized acid and lowers the concentration of H30 +. 17. If an acid is added to a solution of a weak base and its salt, (a) more water is formed and more weak base ionizes; (b) hydronium-ion concentration decreases; (c) more hydroxide ion is formed; (d) more nonionized weak base is formed. Chemical Equilibrium HRW material copyrighted under notice appearing earlier in this work.. Chapter 19 93