For a chemical reaction, the equation of which is: MgO + 2 HNO3 = Mg (NO3) 2 + H2O, the following calculation

| January 11, 2021 | education

For a chemical reaction, the equation of which is: MgO + 2 HNO3 = Mg (NO3) 2 + H2O, the following calculation problems are proposed: a) How much acid is required to interact with 0.5 kmol of MgO? b) Find the mass of a 12% acid solution required for interaction with 180 g of MgO containing 5% impurities?

A).
MgO + 2HNO3 = Mg (NO3) 2 + H2O.
There is 2 mol of HNO3 per mole of MgO.
The substances are in quantitative ratios of 1: 2.
The amount of HNO3 substance is 2 times more than MgO.
n (HNO3) = 2n (MgO) = 0.5 kmol × 2 = 1 kmol.
B).
Let’s find the mass of MgO without impurities.
100% – 5% = 95%.
180 g – 100%,
X- 95%,
X = (95% × 180 g): 100% = 171 g.
Find the amount of MgO.
n = m: M.
M (MgO) = 40 g / mol.
n = 171 g: 40 g / mol = 4.275 mol.
Let’s find the quantitative ratios of substances.
MgO + 2HNO3 = Mg (NO3) 2 + H2O.
There is 2 mol of HNO3 per mole of MgO.
The substances are in quantitative ratios of 1: 2.
The amount of HNO3 substance is 2 times more than MgO.
n (HNO3) = 2n (MgO) = 4.275 kmol × 2 = 8.55 mol.
Let’s find the mass of HNO3.
M (HNO3) = 63 g / mol.
m = n × M.
m = 63 g / mol × 8.55 mol = 538.65 g.
W = m (substance): m (solution) × 100%,
hence m (solution) = m (substance): w) × 100%.
m (solution) = (538.65: 12) × 100% = 4488.75 g.
Answer: 4488.75 g.



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