A first order reaction has a rate constant `1.15 xx 10^(-3)s^(-1)`. How long will 5g of this reacant take to reduce to 3g ?

Explanation

Data, `[R]_(0) (5)/(M)' [R] (3)/(M)` M is molar mass of the reactant
` k = 1.15 xx 10^(-3)s^(-1)`
Formula: `k = (2.303)/(t) log ""([R]_(0))/([R]) " " `t = (2.303)/(1.15 xx 10^(-3)) log ""((5)/(M))/((3)/(M))`
` t = (2.303)/(1.15 xx 10^(-3)) xx 0.2218 " " t 444 s.`