Chapter 6 Answers

CHAPTER 6 ANSWERS

CYU 6.1 p. 217

(a) Neutralization

(b) Synthesis

(d) Synthesis

(e) Combustion

(f) Double replacement

(g) Single replacement

(h) Neutralization

(i) Decomposition

(j) Single replacement

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.

(a) Synthesis

4Na + O2 2Na2O

(b) Double replacement

Na2SO4 + CaCl2 2NaCl + CaSO4

C3H8 + 5O2 3CO2 + 4H2O

(d) Neutralization

H2SO4 + 2KOH K2SO4 + 2H2O

(e) Decomposition

2AlCl3 2Al + 3Cl2

f) Single replacement

3Cd + 2Au(NO3)3 3Cd(NO3)2 + 2Au

(g) Double replacement

Sr(OH)2 + PbBr2 SrBr2 + Pb(OH)2

(h) Combustion

C6H12O6 + 6O2 6CO2 + 6H2O

(i) Synthesis

2N2 + 3O2 2N2O3

(j) Single replacement

2HNO3 + Zn Zn(NO3)2 + H2

(a) Synthesis

6Na + N2 2Na3N

(b) Decomposition

2AlF3 2Al + 3F2

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

(a) Neutralization

(b) Synthesis

(d) Decomposition

(e) Neutralization

(f) Double replacement

(g) Single replacement

(h) Single replacement

(i) Double replacement

(j) Combustion

(a) Al + F2 AlF3

(b) K + O2 K2O

(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

(a) Decomposition

(b) Synthesis

(d) Single replacement, combustion

(e) Combustion

(f) Double replacement, neutralization

(g) Single replacement

(a) Concentration

(b) Surface area

(d) Concentration

(e) Concentration

(f) Catalyst

(g) Surface area

(h) Concentration

(a) Synthesis

4Li + O2 2Li2O

(b) Single replacement

3Mg + 2AlCl3 3MgCl2 + 2Al

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 twoliquids that completely mix into each other,are not affected by surface area considerations.If the reaction system has two or more distinctregions, such as a solid placed in a liquid, thenthere is a surface and surface area is a factor.

7. Surface area > temperature > concentration