Q24.76P - Chemistry: Molecular Nature Of Matter And Change

Question

Arsenic- decays with an energy of ${\mathbf{\text{1.57×10}}}^{\mathbf{\text{ - 15}}}\mathbf{\text{ kJ}}$ per nucleus. Convert this energy into 

(a) eV;

(b) MeV.

Step-by-Step Solution

Answer

$$\begin{gathered} {\text{a) 9.80×10}}^{\text{6}}\text{ eV} \\ \text{b) 9.80 MeV} \end{gathered}$$

Step 1:

-${\text{1 MeV = 10}}^{\text{6}}\text{ eV}$

-${\text{1 MeV = 1.602×10}}^{\text{ - 13}}\text{ J}$

-${\text{1 eV = 1.602×10}}^{\text{ - 19}}\text{ J}$

(a)

We have to convert ${\text{1.57×10}}^{\text{ - 15}}\text{ kJ}$ into electron volts.

${\text{1.57×10}}^{\text{ - 15}}\text{ kJ}={\text{1.57×10}}^{\text{ - 15}}\text{ kJ×}\frac{1000 \text{J}}{1 \text{kJ}}\text{×}\frac{{\displaystyle \text{1 eV}}}{{\displaystyle {\text{1.602×10}}^{\text{ - 19}}\text{ J}}}=\text{9.80}{\times 10}^{\text{ 6}} \mathrm{eV}$

(b)

We have to convert ${\text{1.57×10}}^{\text{ - 15}}\text{ kJ}$ into electron volts.

${\text{1.57×10}}^{\text{ - 15}}\text{ kJ}={\text{9.80×10}}^{\text{6}}\text{ eV×}\frac{\text{1 MeV}}{{\text{10}}^{\text{6}}\text{ eV}}=\text{9.80 MeV}$