Dissociation of strong acids?

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  • Dissociation of strong acids?


Answer #1 | 14/01 2014 13:37
Let us have a look at what 0.1M HCl actually means. We know that M represents moles per litre. So, if we have 0.1 M HCl, it means we have 0.1 moles of HCl in 1 litre of water. You also know that the HCl will dissociate completely to form H+ and Cl-. If we look at the following dissociation equation: HCl --> H+ + Cl- we can see that for every 1 mole of HCl, we form 1 mole of H- and 1 mole of Cl-. So, if we have 0,1 moles of HCl, there should be 0.1 moles of H+ AND 0.1 moles of Cl-. The volume of water is still the same - 1 litre. So, the concentration of H+ is 0.1 M and the concentration of Cl- is also 0.1M.
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Answer #2 | 14/01 2014 10:19
I do not know what your problems is: You have stated quite correctly that HCl dissociates fully , so that HCl → H+ + Cl- If you prepare a solution that is 0.1M in HCl it will really consist of H+ ions and Cl- ions in solution - both of which are 0.1M concentration. Also if you prepare a 0.5M solution of HCl it will really consist of 0.5M H+ and 0.5M Cl- ions in solution In both cases there will be no undissociated HCl in solution.

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