CHAPTER 6 ANSWERS
CYU 6.1 p. 217
1.
(a) Neutralization
(e) Combustion
(i) Decomposition
(b) Synthesis
(f) Double replacement
(j) Single replacement
(c) Double replacement
(g) Single replacement
(d) Synthesis
(h) Neutralization
2. In combustion, the compound is an organic compound containing carbon, hydrogen, and possibly oxygen. Also, the
element in a combustion reaction is oxygen. In a single replacement reaction, the compound is inorganic. There is a
slight overlap between these two classifications, in that a rapid reaction of anything with oxygen can be called
combustion. (For the purpose of this course, combustion is restricted to an organic compound reacting with oxygen.)
3. The reaction of iron metal with oxygen is classified as synthesis in this course. However, if the reaction happens
quickly, it could be considered combustion.
4.
(a) Synthesis
f) Single replacement
4Na + O2 2Na2O
3Cd + 2Au(NO3)3 3Cd(NO3)2 + 2Au
(b) Double replacement
(g) Double replacement
Na2SO4 + CaCl2 2NaCl + CaSO4
Sr(OH)2 + PbBr2 SrBr2 + Pb(OH)2
(c) Combustion
(h) Combustion
C3H8 + 5O2 3CO2 + 4H2O
C6H12O6 + 6O2 6CO2 + 6H2O
(d) Neutralization
(i) Synthesis
H2SO4 + 2KOH K2SO4 + 2H2O
2N2 + 3O2 2N2O3
(e) Decomposition
(j) Single replacement
2AlCl3 2Al + 3Cl2
2HNO3 + Zn Zn(NO3)2 + H2
5.
(a) Synthesis
6Na + N2 2Na3N
(b) Decomposition
2AlF3 2Al + 3F2
(c) Single replacement
3CuSO4 + 2Al Al2(SO4)3 + 3Cu
(d) Combustion
H2SO4 + 2KOH K2SO4 + 2H2O
(e) Combustion
2C4H10 + 13O2 8CO2 + 10H2O
(f) Double replacement
AgNO3 + NaBr NaNO3 + AgBr
(g) Single replacement
2CsI + Cl2 2CsCl + I2
(h) Neutralization
HCl + NaOH NaCl + H2O
(i) Double replacement
K2Cr2O7 + 2AgNO3 Ag2Cr2O7 + 2KNO3
(j) Combustion
C5H10O5 + 5O2 5CO2 + 5H2O
6. 2 Fe + 3Cl2 2FeCl3
Reading Check Answers, p. 274
1. The brighter light of a hot glow stick is due to a faster reaction rate caused by heating.
2. Raising the temperature of a chemical reaction increases the reaction rate.
3. Cooling decreases the frequency at which particles of reactants can collide.
4. Cooling lowers the energy of the collisions between reactant particles.
Reading Check Answers, p. 276
1. Increasing concentration increases the chance of reactant particles colliding with each other. This increases the
reaction rate.
2. Yes. Increasing the pressure of a gas by adding more gas to the same volume or by decreasing the volume of the
same amount of gas both increase the concentration of a gas.
3. Yes. Adding more of the dissolved substance and allowing it to dissolve increases the concentration of the substance.
4. Increasing the surface area of a reactant increases the chance of reactant particles colliding, which increases the
rate.
CYU 6.2 p. 281
1. Accept all logical answers. For example, a high reaction rate helps make explosives useful in highway construction
and demolishing buildings. It also increases the rate at which cooking can occur. The fast rates of reactions in living
things make it possible for the living things to stay alive.
2. Accept all logical answers. For example, refrigeration slows the rate of reactions that cause the decomposition of
foods. Rusting can be limited by slowing the reactions that produce it. Keeping explosive dusts in an inert atmosphere or
keeping them in a compact form reduces the opportunity for a dust explosion to occur.
3. Enzymes are biological catalysts that increase the rate of chemical reactions in order for an organism to stay alive.
4. Increasing concentration of a reactant usually increases the rate of a reaction.
5. A spoonful of sugar has greater surface area than a sugar cube because, in the sugar cube, most of the sugar is on
the inside of the material; while in the spoon, the large number of particles of sugar has a large surface.
6. Increasing surface area increases the rate of a reaction.
7. For example, when two gases react, there is no surface between them. Hydrogen and oxygen gases react to produce
water, and surface area is not a factor.
8. A catalyst makes it possible for reactions to occur with less energy than reactions that do not have a catalyst. The
catalyst helps molecules line up better so that, when they collide with each other, the reaction takes place with less
energy than would otherwise be required.
9. (a) Raising the temperature, increasing the concentration
(b) Raising the temperature, adding a catalyst
(c) Raising the temperature increases the number of collisions and also makes them more effective because the
collisions happen with greater energy.
10. Raising the temperature increases the number of collisions and also gives the collisions a greater amount of energy.
11. Increasing the surface area gives greater opportunity for reactant particles to collide. This increases the rate of
reaction.
12. Increasing the concentration of a reactant gives a greater opportunity for reactant particles to collide. This increases
the rate of a reaction.
13. A catalyst helps reactant molecules to line up more effectively than without a catalyst. This allows the reaction to
happen with less energy.
CHAPTER 6 REVIEW p. 282
1.
(a) Neutralization
(b) Synthesis
(c) Synthesis
(d) Decomposition
(e) Neutralization
(f) Double replacement
(g) Single replacement
(h) Single replacement
(i) Double replacement
(j) Combustion
2.
(a) Al + F2 AlF3
(b) K + O2 K2O
(c) C2H6 + O2 CO2 + H2O
(d) C6H12O4 + O2 CO2 + H2O
(e) Rb2O Rb + O2
(f) Sr + F2 SrF2
(g) BaCl2 + Pb(NO3)2 Ba(NO3)2 + PbCl2
(h) AgNO3 + K2Cr2O7 KNO3 + Ag2Cr2O7
(i) Br2 + NiI3 NiI3 + Br2
(j) Cl2 + Mg3N2 MgCl2 + N2
(k) HCl + Mo(OH)2 MoCl2 + H2O
(l) Sn(OH)2 + HClO3 Sn(ClO3)2 + H2O
(m)Al + CuI2 AlI3 + Cu
(n) Mg + FeF2 MgF2 + Fe
3.
(a) Decomposition
(b) Synthesis
(c) Neutralization
(d) Single replacement,
combustion
(e) Combustion
(f) Double replacement,
neutralization
(g) Single replacement
4.
(a) Concentration
(b) Surface area
(c) Temperature
(d) Concentration
(e) Concentration
(f) Catalyst
(g) Surface area
(h) Concentration
5.
(a) Synthesis
4Li + O2 2Li2O
(b) Single replacement
3Mg + 2AlCl3 3MgCl2 + 2Al
(c) Combustion
2C4H10 + 13O2 8CO2 + 10H2O
(d) Neutralization
HCl + LiOH LiCl + H2O
(e) Decomposition
2Al2O3 4Al + 3O2
(f) Single replacement
3Sn + 4Au(NO3)3 3Sn(NO3)4 + 4Au
(g) Double replacement
2Ba(OH)2 + PbBr4 2BaBr2 + Pb(OH)4
(h) Combustion
2C3H8O3 + 7O2 6CO2 + 8H2O
(i) Synthesis
N2 + 2O2 2NO2
6. Reaction systems that do not have a surface, such as between two gases or between two liquids that completely mix
into each other, are not affected by surface area considerations. If the reaction system has two or more distinct regions,
such as a solid placed in a liquid, then there is a surface and surface area is a factor.
7. Surface area > temperature > concentration