Question 1 Answer and Explanation _ACT December 2018 Form B05 Science Section

Passage I

A reaction is at equilibrium when the rate of the forward reaction equals the rate of the reverse reaction. At equilibrium, the ratio of product concentration(s) to reactant concentration(s) is the equilibrium constant, K.

Consider the following reaction at equilibrium:

X + Y $leftrightharpoons$ Z

For this reaction, K is given by:

$K=frac{left[{Z}right]}{left[{X}right]left[{Y}right]}$

The brackets ([ ]) around the symbol for a substance indicate the equilibrium concentration of the substance.

This reaction was studied in 10 trials. Trials 1-5 were conducted at the same temperature (see Table 1 ) , and Trials 6-10 were conducted at different temperatures (see Table 2).

1. According to Table 1, in Trial 5. what was the equilibrium concentration of Z ?

A. 0.10 mol/L

B. 0.50 mol/L

C. 2.00 mol/L

D. 2.50 mol/L

Answer and Explanation

Your Answer is

Correct Answer is B

Explanation

Through the explanation of brackets[ ] under the formula in the article, we understand that [Z] in table 1 is the equilibrium concentration of Z, so directly look at trail 5 of table 1, [Z] should be 0.50 mol/L< /p>