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Question

If a 5.4 M solution of Ca(NO₃)₂ dissociates completely in water, what is the final [NO₃^-]?

Answer 1

Look at the dissociation of Ca(NO₃)₂...

Ca(NO₃)₂ ==> Ca²⁺(aq) + 2NO₃^-(aq) .. note there are 2 NO₃^- for each 1 Ca²⁺.

5.4 M Ca(NO₃)₂ produces 5.4 M Ca²⁺ and 2 x 5.4 M = 10.8 M NO₃^-