WS 2 answers

WS 2: Writing Balanced Chemical Equations
Step 1: Circle the reactants and underline the products in the problems below.
Step 2: Write the unbalanced equations; show all states of matter.
Step 3: Balance the equation
1. Fluorine gas reacts with solid sodium chloride to form solid sodium fluoride and chlorine gas.
F2(g) + 2 NaCl(s)  2 NaF(s) + Cl2(g)
2. Nitrous oxide gas (systematic name: dinitrogen monoxide) and water vapor are produced by carefully heating
solid ammonium nitrate.
2 NH4NO3(s)  N2O(g) + 2 H2O(g)
3. At high temperatures and in the presence of a catalyst, nobles gases can be made to form stable compounds.
Such an example is xenon gas which combines with fluorine gas to produce solid xenon tetrafluoride.
+ 2 F2(g)  XeF4(g)
4. Liquid phosphorus trichloride reacts with water to form phosphorous acid and hydrochloric acid in solution.
PCl3(l) + 3 H2O(l)  H3PO3(aq) + 3 HCl(aq)
5. Solid manganese(II) peroxide reacts with aqueous hydrochloric acid to form manganese(II) chloride, chlorine
gas, and water.
MnO2(s) + 4 HCl(aq)  MnCl2(aq) + Cl2(g) + 2 H2O(l)
6. When aqueous solutions of potassium chromate and barium chloride are mixed, barium chromate settles out of
solution as a solid leaving potassium chloride in solution.
K2CrO4(aq) + BaCl2(aq)
 BaCrO4(s)
+ 2 KCl(aq)
7. When lead(II) sulfide is heated to high temperatures in pure oxygen gas, solid lead(II) oxide forms with the
release of gaseous sulfur dioxide.
2 PbS(s) + 3 O2(g)  2 PbO(s) + 2 SO2(g)
8. Aqueous magnesium nitrate reacts in solution with aqueous potassium hydroxide to yield a magnesium
hydroxide precipitate and dissolved potassium nitrate.
Mg(NO3)2(aq) + 2 KOH(aq)  Mg(OH)2(s) + 2 KNO3(aq)
9. Solid mercury(I) oxide when heated yields pure mercury metal and oxygen gas.
2 Hg2O(s)  4 Hg(l) + O2(g)
10. Carbon dioxide gas and water vapor are produced when ethane gas (C2H6) burns in the presence of atmospheric
2 C2H6(g) + 7 O2(g)  4 CO2(g) + 6 H2O(g)