Answer : The mass of A remaining after 1.27 min is, 13.7 grams
Explanation :
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant = [tex]0.0265s^{-1}[/tex]
t = time passed by the sample = 1.27 min = 76.2 s (1 min = 60 s)
a = initial amount of the reactant = 16.74 g
a - x = amount left after decay process = ?
Now put all the given values in above equation, we get
[tex]76.2=\frac{2.303}{0.0265}\log\frac{16.74}{a-x}[/tex]
[tex]a-x=13.7g[/tex]
Therefore, the mass of A remaining after 1.27 min is, 13.7 grams
