Question

The following reaction is first order in N₂O₅ :

N₂O₅ (g)→ NO₃(g) + NO₂(g)

The rate constant for the reaction at a certain temperature is 0.053/s

Calculate the rate of reaction when [N₂O₅]=0.055M

What would the rate of reaction be at the same concentration if the reaction was second order? Zero order? (Assume same numerical value for the rate constant but with correct units)

Answer 1

when the reaction is in first order rate will be : r = k X [N2O5]
where k is rate constant = 0.053 /s
[N2O5] = concentration of N2O5 at any time t..
so r = 0.053 X 0.055 = 2.915 X 10^-3 mole/L/s

similalrly when the reaction is second order : r = k X [N2O5]^2
k = rate constant for second order = 0.053 L/mole/s
so r = 0.053 X (0.055)^2 = 0.053 X 3.025 X 10^-3 = 1.6033 X 10^-4 mole/L/s

when the reaction is zero order : r = k X [N2O5]^0 = k X 1 = k
where k is rate constant for zero order = 0.053 mole/L/s
so r = 0.053 mole/L/s