# How many calcium ions is needed to displace hydronium ions in an strong acid ion exchange resin?

If 1 mole of Ca2+ can displace 2 moles of Na+ in an ion exchange resin, can it do the same for H+? Will Ca2+ ion displace 2 moles of H+ in a strong acid resin?

## 1 Answer

Yes and no.

Yes, as $$\ce{1 Ca^2+}$$ displaces $$\ce{2 H+}$$.

No, as you need to involve more then $$\ce{1 Ca^2+}$$ to displace $$\ce{2 H+}$$ for exchange comparable with ionex capacity, as some $$\ce{Ca^2+}$$ passes through before $$\ce{H+}$$ is washed out.

• I see. So to completely wash out the H+ ion in the solution, Ca2+ needed to be in excess? Am I right? – Kent de los Reyes Jul 30 '19 at 7:12
• Yes, you are. But not in so big excess as opposite, i.e. washing out calcium. Strong catexes prefer calcium to hydrogen, in contrary to weak catexes.. – Poutnik Jul 30 '19 at 7:23
• Thank you! This helped me a lot on my exam. – Kent de los Reyes Jul 30 '19 at 7:27
• It should not. Using SE to solve exam tasks is a bad way to use it. – Poutnik Jul 30 '19 at 7:46
• We have a policy which states that ‎you should show your thoughts, effort and attempts to understand underlaying principles. It'll make us certain that ‎we aren't doing your homework for you, and that the Q/A is beneficial for broad audience. Basically any question with the wording your question has is considered homework; it needn't be literally one. It can be self-study questions, puzzles, worked examples etc. – Poutnik Jul 30 '19 at 7:48