Peroxodisulfuric acid $H X_{2} S X_{2} O X_{8}$ has one O-O bond. How many moles of oxygen atoms with oxidation number $- 1$ are present in $19.4 g$ of it? (H 1, S 32, O 16.) Give two decimal places.

Numerical answer type, answer in mol, tolerance 0.005.

Answer: 0.2 mol

Molar mass

= 2 (1) + 2 (32) + 8 (16) = 194 g/mol

. Moles of acid

= 19.4/194 = 0.100

. Each molecule has 2 peroxide O atoms, so the moles of

- 1

oxygen

= 0.100 \times 2 = 0.200