To dissolve 19.6 g of metal (II) hydroxide, 25.2 g of nitric acid were required. Determine the formula of the hydroxide.

Let’s denote the unknown metal – R.

Let’s compose the reaction equation:

R (OH) 2 + 2 HNO3 = R (NO3) 2 + 2 H2O

According to the equation: in the reaction 2 mol of HNO3. Let’s find the mass by the formula: m = n * M

m (HNO3) = 2 mol * (1 + 14 + 16 * 3) = 126 g

According to the equation: in the reaction 1 mol of R (OH) 2. We find the mass, denoting Ar (R) = x

m (R (OH) 2) = 1 mol * (x + 16 * 2 + 1 * 2) = (x +34)

We make the proportion:

19.6 g R (OH) 2 – 25.2 g HNO3

(х +34) R (OH) 2 – 126 g HNO3

Hence, (x + 34) = 19.6 * 126 / 25.2 = 98

x = 98 – 34 = 64

Ar (R) = 64. Unknown metal – copper.