One chemistry question please help!!?

[匿名]

2016-10-02 6:19 pm

The equation X + Y yields 2Z has the rate law equation shown below. Which of the following statements best describes the relationship of X on the rate of the reaction?

rate = k[X]2[Y]

Changing X has no effect on the reaction rate.
Doubling X causes the reaction rate to quadruple.
Dividing X by two causes the reaction rate to be cut in half.
Multiplying X by three also increases the reaction rate by three times.

回答 (1)

wanszeto

2016-10-02 6:38 pm

✔ 最佳答案

The answer : Doubling [X] causes the reaction rate to quadruple.

Rate = k [X]² [Y]
The reaction is second order with respect to X.

Hence, when keeping [Y] constant :
Rate = constant × [X]²
i.e. Rate ∝ [X]²

The statement "changing [X] has no effect on the reaction rate" is FALSE.
As Rate ∝ [X]², changing [X] would cause the change in reaction rate.

The statement "doubling [X] causes the reaction rate to quadruple" is TRUE.
This is because Rate ∝ [X]².

The statement "dividing [X] by two causes the reaction rate to be cut in half" is FALSE.
As Rate ∝ [X]², dividing [X] by two causes the reaction rate will be reduced to one-fourth.

The statement "multiplying [X] by three also increases the reaction rate by three times" is FALSE.
As Rate ∝ [X]², multiplying [X] by three also increases the reaction rate by SIX times (or to NINE times).

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