4.2 Classifying chemical reactions  (Page 11/34)

Calcium propionate is sometimes added to bread to retard spoilage. This compound can be prepared by the reaction of calcium carbonate, CaCO ₃ , with propionic acid, C ₂ H ₅ CO ₂ H, which has properties similar to those of acetic acid. Write the balanced equation for the formation of calcium propionate.

Complete and balance the equations of the following reactions, each of which could be used to remove hydrogen sulfide from natural gas:

(a) $\text{Ca}{(\text{OH})}_2(s)+{\text{H}}_2\text{S}(g)⟶$

(b) ${\text{Na}}_2{\text{CO}}_3(aq)+{\text{H}}_2\text{S}(g)⟶$

Copper(II) sulfide is oxidized by molecular oxygen to produce gaseous sulfur trioxide and solid copper(II) oxide. The gaseous product then reacts with liquid water to produce liquid hydrogen sulfate as the only product. Write the two equations which represent these reactions.

Write balanced chemical equations for the reactions used to prepare each of the following compounds from the given starting material(s). In some cases, additional reactants may be required.

(a) solid ammonium nitrate from gaseous molecular nitrogen via a two-step process (first reduce the nitrogen to ammonia, then neutralize the ammonia with an appropriate acid)

(b) gaseous hydrogen bromide from liquid molecular bromine via a one-step redox reaction

(c) gaseous H ₂ S from solid Zn and S via a two-step process (first a redox reaction between the starting materials, then reaction of the product with a strong acid)

Calcium cyclamate Ca(C ₆ H ₁₁ NHSO ₃ ) ₂ is an artificial sweetener used in many countries around the world but is banned in the United States. It can be purified industrially by converting it to the barium salt through reaction of the acid C ₆ H ₁₁ NHSO ₃ H with barium carbonate, treatment with sulfuric acid (barium sulfate is very insoluble), and then neutralization with calcium hydroxide. Write the balanced equations for these reactions.

Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):

(a) ${\text{Sn}}^{\mathrm{4+}}(aq)⟶{\text{Sn}}^{\mathrm{2+}}(aq)$

(b) ${\left[\text{Ag}{({\text{NH}}_3)}_2\right]}^{\text{+}}(aq)⟶\text{Ag}(s)+{\text{NH}}_3(aq)$

(c) ${\text{Hg}}_2{\text{Cl}}_2(s)⟶\text{Hg}(l)+{\text{Cl}}^{\text{−}}(aq)$

(d) ${\text{H}}_2\text{O}(l)⟶{\text{O}}_2(g)(\text{in acidic solution})$

(e) ${\text{IO}}_3{}^{\text{−}}(aq)⟶{\text{I}}_2(s)$

(f) ${\text{SO}}_3{}^{\mathrm{2-}}(aq)⟶{\text{SO}}_4{}^{\mathrm{2-}}(aq)\text{(in acidic solution)}$

(g) ${\text{MnO}}_4{}^{\text{−}}(aq)⟶{\text{Mn}}^{\mathrm{2+}}(aq)\text{(in acidic solution)}$

(h) ${\text{Cl}}^{\text{−}}(aq)⟶{\text{ClO}}_3{}^{\text{−}}(aq)\text{(in basic solution)}$

Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):

(a) ${\text{Cr}}^{\mathrm{2+}}(aq)⟶{\text{Cr}}^{\mathrm{3+}}(aq)$

(b) $\text{Hg}(l)+{\text{Br}}^{\text{−}}(aq)⟶{\text{HgBr}}_4{}^{\mathrm{2-}}(aq)$

(c) $\text{ZnS}(s)⟶\text{Zn}(s)+{\text{S}}^{\mathrm{2-}}(aq)$

(d) ${\text{H}}_2(g)⟶{\text{H}}_2\text{O}(l)(\text{in basic solution})$

(e) ${\text{H}}_2(g)⟶{\text{H}}_3{\text{O}}^{\text{+}}(aq)(\text{in acidic solution})$

(f) ${\text{NO}}_3{}^{\text{−}}(aq)⟶{\text{HNO}}_2(aq)\text{(in acidic solution)}$

(g) ${\text{MnO}}_2(s)⟶{\text{MnO}}_4{}^{\text{−}}(aq)\text{(in basic solution)}$

(h) ${\text{Cl}}^{\text{−}}(aq)⟶{\text{ClO}}_3{}^{\text{−}}(aq)\text{(in acidic solution)}$

Balance each of the following equations according to the half-reaction method:

(a) ${\text{Sn}}^{\mathrm{2+}}(aq)+{\text{Cu}}^{\mathrm{2+}}(aq)⟶{\text{Sn}}^{\mathrm{4+}}(aq)+{\text{Cu}}^{\text{+}}(aq)$

(b) ${\text{H}}_2\text{S}(g)+{\text{Hg}}_2{}^{\mathrm{2+}}(aq)⟶\text{H}g(l)+\text{S}(s)\text{(in acid)}$

(c) ${\text{CN}}^{\text{−}}(aq)+{\text{ClO}}_2(aq)⟶{\text{CNO}}^{\text{−}}(aq)+{\text{Cl}}^{\text{−}}(aq)\text{(in acid)}$

(d) ${\text{Fe}}^{\mathrm{2+}}(aq)+{\text{Ce}}^{\mathrm{4+}}(aq)⟶{\text{Fe}}^{\mathrm{3+}}(aq)+{\text{Ce}}^{\mathrm{3+}}(aq)$

(e) $\text{HBrO}(aq)⟶{\text{Br}}^{\text{−}}(aq)+{\text{O}}_2(g)\text{(in acid)}$

Balance each of the following equations according to the half-reaction method:

(a) $\text{Zn}(s)+{\text{NO}}_3{}^{\text{−}}(aq)⟶{\text{Zn}}^{\mathrm{2+}}(aq)+{\text{N}}_2(g)\text{(in acid)}$

(b) $\text{Zn}(s)+{\text{NO}}_3{}^{\text{−}}(aq)⟶{\text{Zn}}^{\mathrm{2+}}(aq)+{\text{NH}}_3(aq)\text{(in base)}$

(c) $\text{CuS}(s)+{\text{NO}}_3{}^{\text{−}}(aq)⟶{\text{Cu}}^{\mathrm{2+}}(aq)+\text{S}(s)+\text{NO}(g)\text{(in acid)}$

(d) ${\text{NH}}_3(aq)+{\text{O}}_2(g)⟶{\text{NO}}_2(g)\text{(gas phase)}$

(e) ${\text{Cl}}_2(g)+{\text{OH}}^{\text{−}}(aq)⟶{\text{Cl}}^{\text{−}}(aq)+{\text{ClO}}_3{}^{\text{−}}(aq)\text{(in base)}$

(f) ${\text{H}}_2{\text{O}}_2(aq)+{\text{MnO}}_4{}^{\text{−}}(aq)⟶{\text{Mn}}^{\mathrm{2+}}(aq)+{\text{O}}_2(g)\text{(in acid)}$

(g) ${\text{NO}}_2(g)⟶{\text{NO}}_3{}^{\text{−}}(aq)+{\text{NO}}_2{}^{\text{−}}(aq)\text{(in base)}$

(h) ${\text{Fe}}^{\mathrm{3+}}(aq)+{\text{I}}^{\text{−}}(aq)⟶{\text{Fe}}^{\mathrm{2+}}(aq)+{\text{I}}_2(aq)$

Balance each of the following equations according to the half-reaction method:

(a) ${\text{MnO}}_4{}^{\text{−}}(aq)+{\text{NO}}_2{}^{\text{−}}(aq)⟶{\text{MnO}}_2(s)+{\text{NO}}_3{}^{\text{−}}(aq)\text{(in base)}$

(b) ${\text{MnO}}_4{}^{\mathrm{2-}}(aq)⟶{\text{MnO}}_4{}^{\text{−}}(aq)+{\text{MnO}}_2(s)\text{(in base)}$

(c) ${\text{Br}}_2(l)+{\text{SO}}_2(g)⟶{\text{Br}}^{\text{−}}(aq)+{\text{SO}}_4{}^{\mathrm{2-}}(aq)\text{(in acid)}$