Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
0 votes

Calculate the energy required to excite one litre of hydrogen gas at 1atm and 298K to the first excited state of atomic hydrogen.The energy for the dissociation of H-H bond is $463KJmol^{-1}$

$\begin{array}{1 1}(a)\;96.4KJ&(b)\;97.32KJ\\(c)\;98.19KJ&(d)\;95.63KJ\end{array}$

Can you answer this question?

1 Answer

0 votes
Mole of $H_2$ present in one litre =$\large\frac{PV}{RT}$
$\Rightarrow \large\frac{1\times 1}{0.0821\times 298}$
$\Rightarrow 0.0409$
Thus energy needed to brak H-H bonds in 0.0409mole of $H_2=0.0409\times 436=17.83KJ$
Also energy needed to excite on H atom from $1^{st}$ to $2^{nd}$ energy level=$13.6(1-\large\frac{1}{4})$$eV$
$\Rightarrow 10.2eV$
$\Rightarrow 10.2\times 1.6\times 10^{-19}J $
$\therefore$ Energy needed to excite $0.0409\times 2\times 6.02\times 10^{23}$ atoms of H=$10.2\times 1.6\times 10^{-19}\times 0.0409\times 2\times 6.02\times 10^{23}J$
$\Rightarrow 80.36KJ$
Total energy needed=$17.83+80.36$
$\Rightarrow 98.19KJ$
Hence (c) is the correct answer.
answered Jan 15, 2014 by sreemathi.v

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App