Determine the number of molecules in oxygen with a mass of 64g, the molar mass of which is 0.032kg / mol.

univerkov | February 11, 2021 | education

To determine the required number of molecules in the oxygen taken, consider the equality: m / MO2 = ν (amount of oxygen substance) = N / Na, from where we express: N = Na * m / MO2.

Const: Na – Avogadro’s number (Na = 6.022 * 10 ^ 23 mol-1); MO2 – the molar mass of oxygen (according to the condition MO2 = 32 * 10 ^ -3 kg / mol).

Data: m is the considered mass of oxygen (m = 64 g; in the SI system m = 64 * 10 ^ -3 kg).

Let’s perform the calculation: N = Na * m / MO2 = 6.022 * 10 ^ 23 * 64 * 10 ^ -3 / (32 * 10 ^ -3) = 1204.4 * 10 ^ 21 molecules.

Answer: 64 g of oxygen contains 1204.4 * 10 ^ 21 molecules.

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