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2CO + O2 → 2CO2<br />
6 If the above reaction takes place inside a sealed reaction chamber, then which of these procedures<br />
will cause a decrease in the rate of reaction?<br />
A raising the temperature of the reaction chamber<br />
B increasing the volume inside the reaction chamber<br />
C removing the CO2 as it is formed<br />
D adding more CO to the reaction chamber<br />
Explanation: Increasing the pressure of a gas is exactly the same as increasing its concentration. If<br />
you have a given mass of gas, the way you increase its pressure is to squeeze it into a smaller<br />
volume. If you have the same mass in a smaller volume, then its concentration is higher.<br />
Because "RT" is constant as long as the temperature is constant, this shows that the pressure is<br />
directly proportional to the concentration. If you double one, you will also double the other. Increasing<br />
the pressure on a reaction involving reacting gases increases the rate of reaction. Changing the<br />
pressure on a reaction which involves only solids or liquids has no effect on the rate.<br />
7 A catalyst can speed up the rate of a given chemical reaction by<br />
A increasing the equilibrium constant in favor of products.<br />
B lowering the activation energy required for the reaction to occur.<br />
C raising the temperature at which the reaction occurs.<br />
D increasing the pressure of reactants, thus favoring products.<br />
Explanation: Catalysts increase the rate of reaction without being used up. They do this by lowering<br />
the activation energy needed. With a catalyst, more collisions result in a reaction, so<br />
the rate of reaction increases. Different reactions need different catalysts. Another important idea<br />
about catalysts is that they are selective. That is the catalyst doesn't just speed up all reactions, but<br />
only a very particular reaction. This is the key to many chemical transformations. When you only want<br />
to perform a particular chemical change, you look for a catalyst that will speed up that specific<br />
reaction but not others. Enzymes are remarkable in this way. Living biological systems require a<br />
myriad of specific chemical transformations and there is a unique enzyme to catalyze each of them.<br />
8 Which reaction diagram shows the effect of using the appropriate catalyst in a chemical reaction?<br />
A<br />
C<br />
B<br />
D<br />
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