Question

For a first order reaction, to obtain a positive slope, we need to plot:

$\left\{\right[A\left]\text{is the concentration of reactant}A\right\}$

• A. ${\log }_{10}\left[A\right]vst$
• B. $-{\log }_e\left[A\right]vst$
• C. ${\log }_{10}\left[A\right]vs\log t$
• D. $\left[A\right]vst$

Answer 1

Answer: (B)

$-{\log }_e\left[A\right]vst$

For a first order reaction, to obtain a positive slope,we need to plot $-lo{g}_{10}\left[A\right]$ vs $t$ or $-lo{g}_e\left[A\right]$ vs $t$
$k=\frac{2.303}{t}log\frac{[A{]}_0}{\left[A\right]}$

$\frac{kt}{2.303}=log[A{]}_0-log[A]$

$log\left[A\right]=log[A{]}_0-\frac{kt}{2.303}$

$-log\left[A\right]=-log[A{]}_0+\frac{kt}{2.303}$