Writing and Balancing Chemical Equations WS 4 - KEY
1.
Solid sodium reacts with oxygen gas to produce solid sodium oxide. Write a word equation for this reaction.
Then write a balanced chemical equation, using the correct chemical formulas and phase symbols.
sodium (s) + oxygen (g)  sodium oxide (s)
4 Na(s) + O2(g)  2 Na2O(s)
2.
Give the word equation and the balanced chemical equation for the decomposition of solid calcium carbonate into
solid calcium oxide and carbon dioxide gas.
calcium carbonate (s)  calcium oxide (s) + carbon dioxide (g)
CaCO3(s)  CaO(s) + CO2(g)
3.
Write the word equation and the balanced chemical equation for the chemical reaction between liquid water and
calcium metal, given that the reaction produces aqueous calcium hydroxide and hydrogen gas.
water (l) + calcium (s)  calcium hydroxide (aq) + hydrogen (g)
2 H2O(l) + Ca(s)  Ca(OH)2(aq) + H2(g)
4.
Give the word equation and the balanced chemical equation for the chemical reaction that produces solid
copper (I) oxide from its elements.
copper (s) + oxygen (g)  copper (I) oxide (s)
4 Cu(s) + O2(g)  2 Cu2O(s)
5.
Write the word equation and the balanced chemical equation for the chemical reaction that occurs when solid
aluminum oxide is decomposed into aluminum and oxygen.
aluminum oxide (s)  aluminum (s) + oxygen (g)
2 Al2O3(s)  4 Al(s) + 3 O2(g)
6.
Liquid bromine combines with gaseous nitrogen to produce gaseous nitrogen tribromide.
Write the word equation and the balanced chemical equation for this synthesis reaction.
bromine (l) + nitrogen (g)  nitrogen tribromide (g)
3 Br2(l) + N2(g)  2 NBr3(g)
7.
Lead (II) sulfate is precipitated from a mixture of water solutions of potassium sulfate and lead (II) nitrate.
Write the word equation and the balanced chemical equation for this double replacement reaction.
potassium sulfate (aq) + lead (II) nitrate (aq)  lead (II) sulfate (s) + potassium nitrate (aq)
K2SO4(aq) + Pb(NO3)2(aq)  PbSO4(s) + 2 KNO3(aq)
8.
Write the word equation and the balanced chemical equation for the synthesis reaction that occurs when ammonia
vapor and hydrogen sulfide gas react to produce solid ammonium sulfide.
(Hint: The chemical formula for ammonia is NH3.)
ammonia (g) + hydrogen sulfide (g)  ammonium sulfide (s)
2 NH3(g) + H2S(g)  (NH4)2S(s)
Writing and Balancing Chemical Equations WS 4 - KEY
9.
Magnesium metal replaces mercury in an aqueous solution of the compound mercury (II) nitrate.
Give the word equation and the balanced chemical equation for this single replacement reaction.
magnesium (s) + mercury (II) nitrate (aq)  mercury (l) + magnesium nitrate (aq)
Mg(s) + Hg(NO3)2(aq)  Hg(l) + Mg(NO3)2(aq)
Honors Solid potassium chlorate is synthesized by combination of solid potassium, chlorine gas, and oxygen gas.
Write the word equation and the balanced chemical equation for this synthesis.
potassium (s) + chlorine (g) + oxygen (g)  potassium chlorate (s)
2 K(s) + Cl2(g) + 3 O2(g)  2 KClO3(s)