The amount of substance (in mol) is found by the formula: n = m / M, where m is the mass of the substance, g; M – molar mass, g / mol. Let us find the molar mass of copper according to the periodic table: M (Cu) = 63.5 g / mol. Then the amount of substance: n = 128 g / 63.5 g / mol = 2 mol.
Answer: n (Cu) = 2 mol.
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