Question

Sucrose hydrolyzes into glucose and fructose. The hydrolysis is a first order reaction. the half life for the hydrolysis of sucrose is 64.2min at 25C. How many grams fo sucrose in 1.25L of a 0.389M solution are hydrolyzed in 1.73hrs?

I started off by finding k the constant
t1/2=0.693/k
64.2min=0.693/k
k=0.01079

I'm not sure what to do after this
I converted the 64.2min into hrs and got k as 0.6477

Answer 1

Since you want the answer in hours I would use the k in the hour units.
How many grams do you have in the solution? 1.25L x 0.389 moles/L x 342.3 grams/mole = ?? (about 166 but that is approximate).
ln(No/N) = kt
I would substitute 166 (or the actual number you obtain) for No, solve for N, and substitute 1.73 for t and the k you have in hr^-1. Solve for N which will be the grams REMAINING after 1.73 hours. That subtracted from the number of grams initially should be the amount decomposed.

Answer 2

ln166.44-lnx=0.64766*1.73
-lnx=1.120-ln166.44
lnx=3.9942
x=E^3.9942
=54.27
166.54-54.27=112g

Answer 3

That looks good to me.

Answer 4

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