(i) What mass of hydrogen peroixde will be present in 2 L of a 5 molar solution ?
(ii) Caluclate the mass of oygen which will be liberated by the decomposition of 200 mL of this solution.

Answer

340g , 16g

Explanation

Molar mass of `H_2 O_2 = 34 g "mol"^(-1)`
1 L of 5 M solution of `H_2 O_2` will contain `H_2 O_2`
`= 34xx5g`
2 L of 5 M solution of `H_2 O_2` will contain `H_2 O_2` = `2xx 34 xx 5 = 340 ` g
200 mL of 5 M solution will contain `H_2 O_2 = (340)/(2000)xx200 =34 g`
`2H_2 O_2 to H_2 O+ O_2`
68 g of `H_2 O_2` on decomposition will give `O_2 = 32 g `
`therefore ` 34 g of `H_2 O_2` on decomposition will give `O_2` = `(36)/(68) xx 34 = 16 g `