Determine the mass fractions of elements in copper oxide (1) and in copper oxide (2).

Determine the mass fractions of elements in copper oxide (1) and in copper oxide (2). Express the found mass fractions as a percentage.

1. Let’s find the mass fractions of elements in copper (I) oxide:

w (Cu) = 2 * Ar (Cu): Mr (Cu2O);

Mr (Cu2O) = 64 * 2 + 16 = 144;

w (Cu) = 128: 144 = 0.8889 or 88.89%;

w (O) = Ar (O): M (Cu2O);

w (O) = 16: 144 = 0.1111 or 11.11%.

2. Let’s calculate the mass fractions of elements in copper (II) oxide:

w (Cu) = Ar (Cu): Mr (CuO);

Mr (CuO) = 64 + 16 = 80;

w (Cu) = 64: 80 = 0.8 or 80%;

w (O) = Ar (O): M (CuO);

w (O) = 16: 80 = 0.2 or 20%.

Answer: 88.89% Cu and 11.11% O in Cu2O; 80% Cu and 20% O in CuO.

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