Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12

# The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume :SO2Cl2 (g) → SO2 (g) + Cl2 (g) - Chemistry

The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume :SO2Cl2 (g) → SO2 (g) + Cl2 (g)

 Experiment Time/s–1 Total pressure/atm 1 0 0.5 2 100 0.6

Calculate the rate of the reaction when total pressure is 0.65 atm.

#### Solution

The thermal decomposition of SO2Cl2 at a constant volume is represented by the following equation.

SO2Cl2 (g) → SO2 (g) + Cl2 (g)

 At t = 0 P_0 0 0 At t = t P_0-p p p

After time, t, total pressure, P_t = (P_0 - p) + p + p

=>P_t = P_0 + p

=>p = P_t - P_0

Therefore P_0 - p = P_0 - (P_t-P_0)

= 2 P0 − Pt

For a first order reaction,

k = 2.303/t log  P_0/(P_0-p)

When t = 100 s, k = 2.303/100s log  0.5/(2xx0.5-0.6)

When Pt = 0.65 atm,

P0 + p = 0.65

⇒ p = 0.65 − P0

= 0.65 − 0.5

= 0.15 atm

Therefore, when the total pressure is 0.65 atm, pressure of SOCl2 is p_(SOCl_2) = P_0 - p

= 0.5 − 0.15

= 0.35 atm

Therefore, the rate of equation, when total pressure is 0.65 atm, is given by,

Rate = k(p_(SOCl_2))

= (2.23 × 10−3 s−1) (0.35 atm)

= 7.8 × 10−4 atm s−1

Concept: Integrated Rate Equations - First Order Reactions
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#### APPEARS IN

NCERT Class 12 Chemistry Textbook
Chapter 4 Chemical Kinetics
Q 21 | Page 119