Question

part b
in the first 22.0 s of this reaction, the concentration of hbr dropped from 0.520 m to 0.471 m. calculate the average rate of the reaction in this time interval.
express your answer in moles per liter per second to two significant figures.
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rate = 0.010 m/s
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begin with a calculation of the change in concentration of hbr and the change in time. then calculate the reaction rate using the expression determined in part a.
you may want to review hint 2. simplify: identify the rate equation.

Explanation:

Step1: Calculate change in HBr concentration

$\Delta[\text{HBr}]=0.471\ M - 0.520\ M=- 0.049\ M$

Step2: Use reaction - rate formula

The rate formula with respect to HBr is $rate =-\frac{1}{2}\frac{\Delta[\text{HBr}]}{\Delta t}$. Given $\Delta t = 22.0\ s$.
Substitute the values: $rate=-\frac{1}{2}\times\frac{- 0.049\ M}{22.0\ s}$
$rate=\frac{0.049\ M}{2\times22.0\ s}$
$rate=\frac{0.049\ M}{44.0\ s}\approx0.0011\ M/s$

Answer:

$0.0011\ M/s$