Upon calcining 116 g of magnesium hydroxide, a solid substance weighing 65 g was obtained.

| March 5, 2021 | education

Upon calcining 116 g of magnesium hydroxide, a solid substance weighing 65 g was obtained. What is this substance? What is its output (in%) of the theoretically possible?

1. According to the condition of the problem, we write down the equation:
m = 116 g. m = 65 g. W -?
Mg (OH) 2 = MgO + H2O – decomposition, magnesium oxide obtained;
2. We make calculations by the formulas:
M Mg (OH) 2 = 58.3 g / mol;
M (MgO) = 40.3 g / mol;
Y Mg (OH) 2 = m / M = 116 / 58.3 = 1.98 mol;
Y (MgO) = 1.98 mol since the amount of these substances is equal to 1 mol according to the equation.
3. Find the mass, product yield:
m (MgO) = Y * M = 1.98 * 40.3 = 79.79 g;
W = m (practical) / m (theoretical) * 100;
W = 65 / 79.79 * 100 = 81.46%
Answer: obtained magnesium oxide weighing 79.79 g, the product yield was 81.46%.



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