\(Ca (OH)_2 + 2HCl \rightarrow Ca Cl_2 + 2H_2 O\)
Explanation:
First of all, let's try to identify the different substances involved in the reaction:
- calcium hydroxide: calcium is the element \(Ca\), while hydroxide corresponds to the ion \(OH^-\). Calcium has 2 valence electrons, so the calcium ion is \(Ca^{2+}\), and since the ion \(OH^-\) has only one negative charge, we need two of them to combine with the calcium ion, therefore: \(Ca(OH)_2\)
- hydrochloric acid: this is an acid, so with one ion of hydrogen \(H^+\), and the other element is the chlorine, which in the ion form is \(Cl^-\), so the hydrochloric acid is \(HCl\)
- calcium chloride: this is the combination of the calcium ion, \(Ca^{2+}\), with the chlorine ion, \(Cl^-\), so the compound is \(CaCl_2\)
- Water: this is given by \(H_2 O\)
so, the reaction is
\(Ca (OH)_2 + HCl \rightarrow Ca Cl_2 + H_2 O\)
However, this reaction is not balanced yet: in fact, we have 2 atoms of oxygen on the left and only one on the right. Moreover, we have 3 atoms of hydrogen on the left and only 2 on the right. Therefore, in order to balance it, we must write:
\(Ca (OH)_2 + 2HCl \rightarrow Ca Cl_2 + 2H_2 O\)
