Question

Concentrated sulfuric acid (98.12 g.mol-1) has a density of 1.5 g/cm3 and is 60 % H2SO4 per mass. The rest is water. How many H+ ions are there in a 45ml concentrated sulfuric acid solution?

Answer 1

There are approx. `5xx10^23` individual hydronium ions.......

Explanation:

We need to find (i) `[H_2SO_4]`, the concentration with respect to `"sulfuric acid"`.

And so we start with a `1*cm^3` volume, which has a mass of `1.5*g`, of which 60% by mass is the acid, i.e. `0.90*g` with respect to sulfuric acid.

And so `"concentration"` `=` `"moles"/"volume"` `=` `((0.90*g)/(98.08*g*mol^-1))/(1.0xx10^-3*L)`

`=9.18*mol*L^-1` WITH RESPECT TO `H_2SO_4(aq)`.

And thus (ii) in a `45*mL` volume, there are `45xx10^-3Lxx9.18*mol*L^-1=0.413*mol` with respect to `H_2SO_4`.

Given that the acid is DIPROTIC, there are thus `0.826*mol` with respect to `H_3O^+` or `H^+`.

To get the number of `H_3O^+` ions, we multiply this quantity by the `"Avocado number"`, i.e.

`0.826*molxx6.022xx10^23*mol^-1=4.97xx10^23` hydronium ions.