Question

The ionisation enthalpy of hydrogen atom is 1.312 ´ 06 J mol–1. The energy required to excite the electron in the atom from n1 = 1 to n2 = 2 is

• A. 8.51 ´ 105 J mol–1
• B. 6.56 ´ 105 J mol–1
• C. 7.56 ´ 105 J mol–1
• D. 9.84 ´ 105 J mol–1

Answer 1

Answer: (D)

9.84 ´ 105 J mol–1

Answer 2

I.E. = 1.312 × 106 J mol–1

The energy required to excite the electron in the atom from n1 = 1 to n = 2.

= 1.312 × 106 $\left\lbrack 1 - \frac{1}{4} \right\rbrack$

= 1.312 × 106 × $\frac{3}{4}$

= 9.84 × 105 J mol–1