Question

Calcium hydroxide + hydrochloric acid mc012-1.jpg calcium chloride + water

Which is the corresponding formula equation?

Answer 1

D) Ca(OH)2(s) + 2HCI(l) -> CaCl2(aq) + 2H2O(l)

Answer 2

`Ca (OH)_2 + 2HCl \rightarrow Ca Cl_2 + 2H_2 O`

Step-by-step 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`