Complete the balanced chemical equation for the following reaction between a weak acid and a strong base. HCN(aq) + Ca(OH)₂(aq) →

Question

what would I do with the Ca and OH?

Answer 1

2 HCN(aq) + Ca(OH)₂(aq) → Ca(CN)₂(aq) + 2 H₂O(l)

The calcium ion has a 2+ charge and the CN ion has a 1- charge, so it will take 2 of the CN^- to bond with the Ca²⁺. The 2 OH^- from Ca(OH)₂ will combine with the 2H⁺ from the 2HCN to form 2 H₂O.

Answer 2

It's important to note the hydroxide ion is a polyatomic ion that stays together and is important for acids and bases. Each hydroxide ion can combine with one hydrogen ion to make a water molecule.

You will need two HCN molecules on the left so that there are enough hydrogen ions for the two hydroxide ions in the calcium hydroxide. This will result in two water molecules on the right of the equation.

The leftover cations and anions can be written together to form a salt. Then consult your solubility chart to see if that salt will be aqueous or if it will precipitate. Don't forget to put parenthesis around the cyanide ion in the calcium cyanide salt and put a 2 subscript outside so that the ion charges balance to zero.

Finally put the correct letters for the phase of the salt (aq if it is soluble and s if it precipitates)