Consider the following reaction: 2HBr( g )H2( g )+Br2( g ) Part A Express the ra

Question

Consider the following reaction:
2HBr(g)H2(g)+Br2(g)

Part A

Express the rate of the reaction in terms of the change in concentration of each of the reactants and products.

Part B

In the first 25.0 s of this reaction, the concentration of HBr dropped from 0.560 M to 0.450 M . Calculate the average rate of the reaction in this time interval.

Express your answer using two significant figures.

Part C

If the volume of the reaction vessel in part (b) was 1.50 L, what amount of Br2 (in moles) was formed during the first 15.0 s of the reaction?

Express your answer using two significant figures.

Consider the following reaction:
2HBr(g)H2(g)+Br2(g)

Part A

Express the rate of the reaction in terms of the change in concentration of each of the reactants and products.

Express the rate of the reaction in terms of the change in concentration of each of the reactants and products. a. Rate=12[HBr]t=[H2]t=[Br2]t b. Rate=[HBr]t=12[H2]t=12[Br2]t c. Rate=12[HBr]t=[H2]t=[Br2]t d. Rate=[HBr]t=12[H2]t=12[Br2]t

Part B

In the first 25.0 s of this reaction, the concentration of HBr dropped from 0.560 M to 0.450 M . Calculate the average rate of the reaction in this time interval.

Express your answer using two significant figures.

Rate = _________   Ms1  

Part C

If the volume of the reaction vessel in part (b) was 1.50 L, what amount of Br2 (in moles) was formed during the first 15.0 s of the reaction?

Express your answer using two significant figures.

______   mol  

Explanation / Answer

The reaction is 2HBr -----> H2 + Br2

The rate of reaction is expressed as

- 1/2 d[HBr]/ d t = d[H2]/dt = d[Br2]/dt

Thus the option C is correct.

Part B

The average rate of reaction = -1/2 (0.45 -0.56)/(25-0)

= 0.0022 M/s

= 2.2 x 10-3 Ms-1

Part C

We have rate = k [HBr]2

At 25 sec, [HBr] = 0.45M and rate = 2.2x10-3 Ms-1

Thus k = 2.2x10-3 Ms-1 /(0.45)2

= 1.09x 10-2 /Ms

2 HBr -----> H2 + Br2

0.56 0 0 at t=0

0.56-x x x at t= 15 sec

The integrated rate equation for second order reaction is

k = 1/at[x/(a-x)]

1.09x10-2  = 1/(0.56x15) [x/(0.56-x)]

solving for x , we get x= 0.505 M

The moles of Br2 in 1.5 L vessel = 0.505 moles/Lx 1.5 L

= 0.757 moles

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