rate of reaction

Question

1. Write the rate expressions for the following reaction:

CH_4(g)      +  2O_2(g) → CO_2(g) + 2 H₂O_(g)

#2 question:

Consider the reaction

N_2(g) + 3 H_2(g) → 2 NH_3(g)

Suppose that at a particular moment during the reaction molecular hydrogen is reacting at the rate of 0.074 M/s.

2 a) At what rate is ammonia being formed?

2b) At what rate is molecular nitrogen reacting?

Answer 1

1). CH_4(g)   +  2O_2(g) ==> CO_2(g) + 2H₂O_(g)

rate = -d[CH₄]/dt

rate = -1/2d[O₂]/dt

rate = +d[CO₂]/dt

rate = +1/2d[H₂O]/dt

2). N2(g) + 3H2(g) ===> 2NH3(g)

a) For every 3 moles/molecules of H2 that disappears, 2 moles/molecules of NH3 appears

rate = -1/3 ∆[H₂]/∆t = +1/2∆[NH₃]/∆t

-1/3(0.074 M/s) = +1/2 (x)

0.0247 M/s = x/2

x = 0.0493 M/s = rate of formation of NH₃

b) For every 3 moles/molecules of H₂ that disappears, 1 mole/molecule of N₂ disappears. So it is at a rate 1/3 that of H₂.

rate = -1/3 ∆[H₂]/∆t = -∆[N₂]/∆t

-1/3(0.074 M/s) = -x

0.0247 M/s = x = rate of disappearance of N₂