Chemistry Chapter 8 Section 1
Writing Chemical equations from word problems.
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Write unbalanced equations for each problem, include states.
Don’t forget the Diatomics. Ammonia = NH3 Acids will be aqueous, unless otherwise indicated.
All ionic compounds are solids, unless dissolved in water. Aqueous = dissolved in water = in solution.
Precipitate = solid = insoluble= cloudy solution.
1. Hydrogen peroxide (H2O2) is a relatively reactive chemical substance. For example, iron in the blood
of a wound is able to catalyze the decomposition of a hydrogen peroxide aqueous solution. When it
decomposes, hydrogen peroxide produces water and oxygen gas. Write an unbalanced chemical
equation for the breakdown of hydrogen peroxide.
2. Solid ammonium carbonate is used as the active ingredient in “smelling salts.” When solid
ammonium carbonate is heated, it decomposes into ammonia gas and carbon dioxide gas. Write and
unbalanced chemical equation for this process.
3. Sulfur dioxide gas may be generated in small quantities in the laboratory by adding aqueous sulfuric
acid to the solid sodium sulfite. The other products of the reaction are aqueous sodium sulfate and
water. Write the unbalanced chemical equation for this process.
4. Calcium metal is moderately reactive. If pieces of calcium are added to water, the metal begins to
bubble as hydrogen gas is formed. The water begins to turn cloudy, as relatively insoluble (solid)
calcium hydroxide begins to form. Write the unbalanced chemical equation for the reaction of
calcium metal with water.
5. When a strip of copper wire is placed in an aqueous solution of silver nitrate, solid silver precipitates
out of solution, as the copper wire dissolves to give a solution of copper(II)nitrate. Write an
unbalanced chemical equation for this process.
6. Liquid Methyl alcohol (methanol: CH3OH) burns cleanly in air (oxygen), producing carbon dioxide gas
and water vapor. Write an unbalanced chemical equation for this reaction.
7. If solutions of lead nitrate and potassium iodide are mixed, a yellow precipitate of lead (II) iodide,
forms immediately and settles from the solution. The liquid remaining is a solution of potassium
nitrate. Write the unbalanced chemical equation for the reaction of lead nitrate with potassium
iodide.
8. If bottles of ammonia and hydrochloric acid are opened near each other, the ammonia and hydrogen
chloride fumes from the bottles react in the air, forming solid ammonium chloride. Chemistry labs
(which usually contain these solutions) often become “dusty” from this process. Write the
unbalanced chemical equation for the reaction of gaseous ammonia with gaseous hydrogen chloride.
9. When sulfuric acid is added to sodium chloride solution and the mixture is heated, hydrogen chloride
gas is generated, after the water is evaporated, a soild residue of sodium sulfate remains. Write an
unbalanced chemical equation for this reaction.
Chemistry Chapter 8 Section 1
Writing Chemical equations from word problems.
2
10. When aqueous potassium chromate is added to a solution of lead(II) nitrate, a bright orange
precipitate of lead(II) chromate forms, leaving potassium nitrate in solution. Write the unbalanced
chemical equation for this process.
11. When sulfuric acid is added to ordinary table sugar (sucrose – C12H22O11), a long black “snake” of
elemental carbon forms, with the release of a cloud of steam (water vapor) and sulfur trioxide. Write
the unbalanced chemical equation for this process.
12. When magnesium metal is heated to several hundred degrees in an atmosphere of pure nitrogen
gas, a green, solid deposit of magnesium nitride forms. Write the unbalanced chemical equation for
this process.
13. When bright red mercury(II) oxide, HgO, is heated in a test tube, oxygen gas evolved, and droplets
of liquid mercury condense at the cooler top of the test tube. Write the unbalanced chemical
equation for this process.
14. The marble used in construction projects consists primarily of polished calcium carbonate. The
marble of many public monuments and buildings is slowly deteriorating as this substance reacts with
the sulfuric acid contained in acid rain. The marble is converted by this reaction into calcium sulfate
and carbon dioxide gas. Although calcium carbonate is insoluble in water calcium sulfate is
somewhat soluble, and as exposure to the acid continues, the monument or building gradually
dissolves. Write the unbalanced chemical equation for the reaction of solid calcium carbonate with
sulfuric acid solution.
15. Ozone gas is a form of elemental oxygen containing molecules with three oxygen atoms. Ozone is
produced from atmospheric oxygen gas by the high-energy outbursts found in lightning storms.
Write an unbalanced equation for the formation of ozone gas from oxygen gas.
16. Sand consists primarily of silicon dioxide. Pure elemental silicon for use in the semiconductor
industry can be produced by reaction of sand with elemental carbon at high temperatures. Carbon
monoxide gas is also a product of the reaction. Write an unbalanced chemical equation for the
reaction of silicon dioxide with carbon.
17. Although they were formerly called the inert gases, the heavier elements of Group 18 do form
relatively stable compounds. For example, at high temperatures in the presence of an appropriate
catalyst, xenon (warrior princess) gas will combine directly with fluorine gas, to produce solid xenon
tetrafluoride. Write the unbalanced chemical equation for this process
18. If ordinary table sugar (sucrose - C12H22O11) is heated strongly in pure oxygen gas, it will ignite and
burn, producing carbon dioxide gas and water vapor. Write the unbalanced chemical equation for
this process.