The thermal decomposition of a compound is of first order. If a sample of the compound decomposes 50 % in 120 min, in what time will it undergo 90 % decomposition?

Question

The thermal decomposition of a compound is of first order. If a sample of the compound decomposes 50 % in 120 min, in what time will it undergo 90 % decomposition? (A) Nearly 240 min  (B) Nearly 480 min  (C) Nearly 450 min  (D) Nearly 400 min

Tardigrade Admin · Accepted Answer

The first order reaction is ⇒ k=(2.303/t) log 10((a/a-x)) For 50 % decomposition, t=120 min a=100 (a-x)=100-50=50 k =(2.303/120) log 10 (100/50) or k=(2.303/120) log 10 2 k=(2.303 × 0.3010/120) or k=(0.6931/120) For 90 % decomposition t=? s a=100(a-x)=100-90=10 k=(2.303/t) log 10 (a/(a-x)) (0.6931/120) =(2.303/t) log 10 (100/10) t =(2.303 × 120/0.6931) t=398.76 min

Q. The thermal decomposition of a compound is of first order. If a sample of the compound decomposes $50%$ in $120$ min, in what time will it undergo $90%$ decomposition?

Nearly $240 min$

Nearly $480 min$

Nearly $450 min$

Nearly $400 min$

Q. The thermal decomposition of a compound is of first order. If a sample of the compound decomposes 50% in 120 min, in what time will it undergo 90% decomposition?

Nearly 240min

Nearly 480min

Nearly 450min

Nearly 400min

Q. The thermal decomposition of a compound is of first order. If a sample of the compound decomposes $50%$ in $120$ min, in what time will it undergo $90%$ decomposition?

Nearly $240 min$

Nearly $480 min$

Nearly $450 min$

Nearly $400 min$