SNC2D Chemical Reactions Strand Review
1. Describe, using an example, how you would recognize the chemical formula of
(a) An element
(b) A Compound
2. Distinguish between the following terms, using specific examples.
(a) Physical and chemical properties
(b) Ionic and molecular compounds
(c) Ionic and Covalent bonds
3. Explain your answers to the following questions.
(a) Is tap water a pure substance?
(b) Is the ability to burn a physical property?
(c) What type of property describes the formation of a new substance?
(d) What kind of elements make up molecular compounds?
(e) What is special about the outer electron orbits of helium, neon, and argon?
(f) What kind of ion has more protons than electrons?
(g) Which are polyatomic ions: hydroxide, chloride, ammonium, sulphide, and carbonate?
4. Copy and complete this table:
Element / Bohr-Rutherford diagram of the atom / Bohr-Rutherford diagram of the ion / Chemical symbol of the ionNa
S
Cl
5. List the numbers and names of atoms in the following molecules.
(a) CO2 (c) CCl4
(b) N2 (d) HBr
6. In which of the following groupings do each of the three ions have the same number of electrons? How many electrons do they have?
(a) O2-, F-, N3- (c) K+, P3-, Ar
(b) Na+, K+, Li+ (d) F-, Cl-, Br-
7. Classify each of the following compounds as ionic or molecular and write their chemical formulas.
(a) potassium chloride (d) calcium iodide
(b) carbon monoxide (e) sulphur dioxide
(c) carbon tetrafluoride (f) lithium oxide
8. Look at your answers to question 7. Explain why Roman numerals are not required to name these compounds.
9. Write the name and chemical formula of the compound that forms when the following pairs of elements combine.
(a) calcium and sulphur
(b) aluminum and chlorine
(c) sodium and phosphorus
(d) aluminum and sulphur
10. Name and write the chemical formula for each of the following compounds involving polyatomic ions.
(a) calcium nitrate (d) Cu(ClO3)2
(b) silver carbonate (e) lead (II) phosphate
(c) Fe(OH)3 (f) HNO3(aq)
11. Imagine the chemical formula of a compound formed from each of these pairs of elements. What are the most likely subscripts in each chemical formula?
(a) An alkali metal and a halogen
(b) An alkaline earth metal and a member of Group 16
(c) An alkali metal and a member of Group 16
12. (a) State the Law of Conservation of mass.
(b) How does this law explain why we balance chemical equations?
13. Zinc oxide, ZnO2, is an active ingredient in some sunscreens. Zinc oxide can be made by heating zinc sulphide strongly in air:
2ZnS(s) + O2(g) → 2ZnO(s) + 2SO2(g)
Referring to this chemical equation, write
(a) The coefficients for zinc sulphide
(b) The number of sulphur atoms in sulphur dioxide
(c) The coefficients for oxygen (the element)
(d) The number of different reactants
(e) The total number of reactant molecules
(f) The states of matter present in this reaction
14. The combustion of hydrocarbons sometimes produces a yellow flame and a sooty residue.
(a) Describe the conditions when this might occur.
(b) Name this type of combustion.
15. Consider the five types of reactions discussed in this chapter. All involve elements and compounds. Identify the type(s) of reaction that has the following reactants:
(a) Two elements
(b) Two compounds
(c) Oxygen and a fuel
(d) Only one compound
(e) An element and a compound
16. The sentences below contain errors or are incomplete. Write complete, correct versions.
(a) A word equation contains words to represent compounds
(b) The total mass of products equals the total mass of reactants unless a gas is produced.
(c) A scientific law is a theory uses to explain experimental observations.
(d) Atoms may be destroyed in some chemical changes.
(e) Compounds are broken down in synthesis reactions.
(f) Elements and compounds react in double displacement reactions.
(g) Elements combine in single displacement reactions.
(h) The products of the combustion of a hydrocarbon are carbon dioxide and oxygen.
17. Hydrogen peroxide is a clear, colourless liquid used to disinfect cuts. The chemical equation for the decomposition of hydrogen peroxide is
2H2O2 (aq) → 2H2O(l) + O2(g)
(a) Explain the difference between the state symbols (aq) and (l).
(b) Predict what you would expect to see in a test tube of hydrogen peroxide undergoing this reaction.
(c) Describe how to tell when the reaction is complete.
18. Balance and classify each of the following chemical equations. (Note that some may fit into more than one category.)
(a) K2O → K + O2
(b) Na + I2 → NaI
(c) Cu(NO3)2 + NaOH → Cu(OH)2 + NaNO3
(d) KClO3 → KCl + O2
(e) Ca(NO3)2 + HBr → CaBr2 + HNO3
(f) Sn(OH)2 → SnO + H2O
(g) P4 + N2O → P4O6 + N2
(h) Fe + Al2(SO4)3 → FeSO4 + Al
(i) AlCl3 + Na2CO3 → Al2(CO3)3 + NaCl
(j) CaCl2 + Al2(SO4)3 → CaSO4 + AlCl3
(k) C3H6 + O2 → CO2 + H2O
19. Write word equations to represent the following changes and identify each of them as a synthesis, decomposition, single displacement, double displacement, or combustion reaction:
(a) A welder’s torch combines acetylene and oxygen gases to form carbon dioxide and water.
(b) A piece of zinc metal added to silver nitrate produces zinc nitrate and silver
(c) When zinc carbonate is heated, zinc oxide and carbon dioxide are produced.
(d) Nitrogen and oxygen gases react in automobile engines to produce poisonous nitrogen dioxide.
(e) Potassium hydroxide and phosphoric acid react to produce water and potassium phosphate.
(f) Hydrogen and nitrogen gases react to make ammonia used in fertilizer.
20. In an experiment, 24 g of magnesium react with 73 g of hydrogen chloride to produce a gas and 95 g of magnesium chloride.
(a) Do these results prove the Law of Conservation of Mass? Explain your answer.
(b) What gas do you think was produced? How could you verify your prediction?
(c) How much of the gas do you think was produced?
21. The following chemical reactions take place, one after another, when an airbag inflates. Balance and classify each reaction.
(a) The gas needed to inflate the bag comes from the reaction of sodium azide, NaN3.
NaN3(s) → N2(g) + Na(s)
(b) The sodium produced in reaction (a) is dangerous. It is removed by a reaction with iron (III) oxide, Fe2O3, in the airbag
Na(s) + Fe2O3(s) → Na2O(s) + Fe(s)
(c) The sodium oxide quickly reacts with carbon dioxide and moisture from the air to form sodium hydrogen carbonate.
Na2O(s) + CO2(g) + H2O(g) → NaHCO3(s)
22. An important industrial process is the refining of iron ore in a blast furnace. In the reaction, carbon displaces iron metal from impure iron (III) oxide. The word equation for this reaction is
Carbon + iron (III) oxide → iron + carbon dioxide
(a) Write a balanced chemical equation for this reaction
(b) What type of reaction is this?
(c) What element displaces the iron?
(d) What type of element is carbon?
(e) How is this reaction different from the pattern of reactions that you learned about in this chapter?
23. Cyclopropane (C3H6) is a hydrocarbon that was once used as an anaesthetic. Its properties, however, made it a safety concern.
(a) What type of chemical reaction could cyclopropane undergo?
(b) Write work, skeleton, and balanced chemical equations for this reaction.
(c) What types of safety precautions do you think medical personnel would have to follow to prevent this reaction?
24. A student placed a piece of zinc metal in a solution of hydrochloric acid. The chemical equation for the reaction that occurred is
Zn(s) + 2HCl(aq) → H2(g) + ZnCl2(aq)
The following data were collected from the experiment:
Initial mass of zinc reacted: 2.5 g
Initial mass of hydrochloric acid 52.6 g
Final mass of solution 54.8 g
(a) Calculate the mass of hydrogen produced.
(b) Do the results of this experiment violate the law of conservation of mass? Explain.
25. When a car burns gasoline, it produces carbon dioxide and water vapour. Assuming that gasoline is octane (C8H18),
(a) What type of chemical reaction is this?
(b) Write the word equation for this chemical reaction.
(c) Write a balanced chemical equation for this reaction.
(d) When a car burns one litre of gasoline, it produces roughly 2.5 kg of carbon dioxide. Make a rough calculation of the number of litres of gasoline that your family car burns in an average week. How many kilograms of carbon dioxide are produced at the same time?
(e) Why is carbon dioxide an environmental concern?
(f) What steps do you think people should take to deal with this environmental concern?
26. Dinitrogen monoxide, N2O(g) is used by some dentists to relax their patients. Nitrous oxide can be made by decomposing solid ammonium nitrate. Water is also produced.
(a) Write the chemical equation for this reaction.
(b) Classify this reaction.
27. Name the following compounds.
(a) H3PO4 (aq) (d) H2SO4 (aq)
(b) HBr (aq) (e) Ca(HCO3)2
(c) Fe(OH)3 (f) KNO3
28. In your own words, define ‘acid’ and ‘base.
29. (a) What gas is produced when acids react with metals like magnesium?
(b) What atoms cause the acidity of an acid?
(c) What colour is bromothymol blue indicator in an acid and in a base?
(d) What are the typical products of a neutralization reaction?
(e) How is pH related to acidity?
(f) What are two pollutants primarily responsible for acid precipitation?
(g) Which human activities are the major sources of these pollutants?
(h) Identify two technologies used to decrease the emissions of these pollutants.
30. Consider these seven compounds: H3PO4(aq), HBr(aq), Fe(OH)3, H2SO4(aq), Ca(HCO3)2, and KNO3. Predict which of these compounds will produce a solution with a pH
(a) less than 7.
(b) greater than 7.
(c) equal to 7.
31. Complete the following word equations
(a) hydrochloric acid + ______→ water + potassium chloride
(b) sulphuric acid + calcium hydroxide → ______+ ______
(c) phosphoric acid + sodium hydroxide → water + ______
32. Write balanced chemical equations for the word equations in question 31.
33. Describe, in your own words, the process of acid-base neutralization.
34. (a) Write the word and chemical equation for the reaction of nitric acid with calcium hydroxide.
(b) This reaction can be classified in two ways. Name these two types of reactions.