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164 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 16
wool mentioned earlier burns more vigorously in 100 percent oxygen gas than in air, which is approximately 20 percent oxygen gas.
Temperature Increasing the temperature of a reaction increases
the frequency of collisions between particles, allowing more opportunities for reaction. Also, increasing temperature raises the average
kinetic energy of particles. Thus, more of the collisions have enough
energy to form an activated complex.
Catalysts A catalyst is a substance that increases the rate of a
chemical reaction without being consumed in the reaction. A heterogeneous catalyst is in a different physical state from the reactants
and works by providing a surface that attracts particles of both reactants and products. This action reduces the activation energy needed
for the reaction because the particles can interact with each other on
the surface.
A homogeneous catalyst is in the same physical state, usually
in solution along with the reactants. For example, strong acids, such
as sulfuric acid, act as homogeneous catalysts by providing a supply
of hydronium ions that can attach to certain kinds of molecules,
breaking covalent bonds and then returning to solution.
Substances called inhibitors are compounds that slow down, or
inhibit, chemical reactions. Compounds used as preservatives in
foods, medicines, and other perishable products are examples of
inhibitors.
Practice Problems
Use the factors discussed in this section to account for the following
observations.
4. When two gases react, compressing the gases generally
increases the rate of reaction.
5. The rate of gaseous reactions can also be increased by pumping
more gas into the reaction container.
6. A pile of kindling consists of small sticks, wood shavings, and
scraps of paper and burns rapidly, giving off enough heat to
begin a fire in a pile of large logs. The logs burn much slower
than the kindling.
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164 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 16
wool mentioned earlier burns more vigorously in 100 percent oxygen gas than in air, which is approximately 20 percent oxygen gas.
Temperature Increasing the temperature of a reaction increases
the frequency of collisions between particles, allowing more opportunities for reaction. Also, increasing temperature raises the average
kinetic energy of particles. Thus, more of the collisions have enough
energy to form an activated complex.
Catalysts A catalyst is a substance that increases the rate of a
chemical reaction without being consumed in the reaction. A heterogeneous catalyst is in a different physical state from the reactants
and works by providing a surface that attracts particles of both reactants and products. This action reduces the activation energy needed
for the reaction because the particles can interact with each other on
the surface.
A homogeneous catalyst is in the same physical state, usually
in solution along with the reactants. For example, strong acids, such
as sulfuric acid, act as homogeneous catalysts by providing a supply
of hydronium ions that can attach to certain kinds of molecules,
breaking covalent bonds and then returning to solution.
Substances called inhibitors are compounds that slow down, or
inhibit, chemical reactions. Compounds used as preservatives in
foods, medicines, and other perishable products are examples of
inhibitors.
Practice Problems
Use the factors discussed in this section to account for the following
observations.
4. When two gases react, compressing the gases generally
increases the rate of reaction.
5. The rate of gaseous reactions can also be increased by pumping
more gas into the reaction container.
6. A pile of kindling consists of small sticks, wood shavings, and
scraps of paper and burns rapidly, giving off enough heat to
begin a fire in a pile of large logs. The logs burn much slower
than the kindling.
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