Q12 / 160 · TS EAMCET 2004 · Chemistry
The molecular formula of potash alum is
- A$\mathrm{KAl}_2 \mathrm{~S}_4 \mathrm{H}_{48} \mathrm{O}_{40}$
- B$\mathrm{K}_2 \mathrm{Al}_2 \mathrm{~S}_4 \mathrm{H}_{48} \mathrm{O}_{39}$
- Correct answerC$\mathrm{K}_2 \mathrm{Al}_2 \mathrm{~S}_4 \mathrm{H}_{48} \mathrm{O}_{40}$
- D$\mathrm{KAl}_2 \mathrm{~S}_4 \mathrm{H}_{48} \mathrm{O}_{40}$
Solution
The composition of potash alum is
or
$$
\mathrm{K}_2 \mathrm{SO}_4 \cdot \mathrm{Al}_2\left(\mathrm{SO}_4\right)_3 \cdot 24 \mathrm{H}_2 \mathrm{O}
$$
$$
\mathrm{K}_2 \mathrm{Al}_2 \mathrm{~S}_4 \mathrm{H}_{48} \mathrm{O}_{40}
$$
It is a double salt of potassium sulphate and aluminium sulphate.
Hence, the correct answer is option: 'C'.