Acetone is one of the most important solvents in organic chemistry. It is used t
ID: 941469 • Letter: A
Question
Acetone is one of the most important solvents in organic chemistry. It is used to dissolve everything from fats and waxes to airplane glue and nail polish. At high temperatures, it decomposes in a first- order process to methane and ketene (CH2-C-O). At 600°C, the rate constant is 8.7 × 10-3 s-1. the most important solvealts in organic nigi temperatures, (a) What is the half-life of the reaction? Give your answer in scientific notation. 10(select) (b) How long does it take for 30% of a sample of acetone to decompose? (c) How long does it take for 94% of a sample of acetone to decompose? Give your answer in scientific notation. ×10(select)Explanation / Answer
if first order process
a)
and K = 8.7*10^-3
then
t1/2 is given as
t1/2 = ln(2)/k
t1/2 = ln(2)/( 8.7*10^-3) = 79.6720 seconds
b)
the law:
ln[A] = ln[A]0 -kt
for A = 0.7A0
then
ln(0.7A0) = ln(A0) - (8.7*10^-3)*t
ln(0.7A0/A0) = - (8.7*10^-3)*t
ln(0.7)/(- (8.7*10^-3)) = t
t = 40.9971 seconds
c)
94%
apply same logic
the law:
ln[A] = ln[A]0 -kt
for A = (1-0.96)A0 = 0.04 A0
then
ln(0.04 A0) = ln(A0) - (8.7*10^-3)*t
ln(0.04 A0/A0) = - (8.7*10^-3)*t
ln(0.04 )/(- (8.7*10^-3)) = t
t = 369.985 seconds
NOTE:
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