How do you work out the mass of NaOH when it reacts with HCL to give 23.5g of NaCl?

[gregbernard2]

please could you write out a full explanation, not in notes as i really dont understand how to work this out

[dundurn]

Elements contribute to the weight of their compounds in the ratio of their atomic weights. So Hydrogen 1, Oxygen 16, Sodium 23, Chlorine 35.5 (all approx - if you need more accurate go look them up).

So in 23.5g of NaCl, the sodium represents 23/58.5 of the total; the chlorine represents 35.5/58.5 of the total. So 9.24g of sodium and 14.26g of chlorine

Now all that sodium started off in the sodium hydroxide and the same ratio rule applies there so the oxygen weighs 9.24 x 16/23g and the hydrogen weighs 9.24x 1/23g

So that's 9.24g sodium, 6.43g of oxygen and .4g of hydrogen giving 16.07g of sodium hydroxide.