How much of a substance is contained in 140 calcium oxide?

m (CaO) = 140 g.

n (CaO) -?

If we know the mass of a substance, then its amount can be found by the formula n = m / M (Where n is the amount of the substance, m is the mass of the substance, M is the molar mass of the substance).
Molar mass (M) of calcium oxide (CaO) = 140 g / mol.
Now we substitute the known to the formula for finding the amount of substance.
n (CaO) = 140 g / 140 g / mol.
n (CaO) = 1 mol.

Answer: n (CaO) = 1 mol.

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