When processing 10 g of a mixture of aluminum and silver with hydrochloric acid, 2.8 liters of hydrogen were released, the mass fraction of aluminum in the mixture.
1. From the proposed mixture, aluminum enters into the reaction, since silver is a much less active metal and is located in the electrochemical series after hydrogen:
2Al + 6HCl = 2AlCl3 + 3H2 ↑;
2. Calculate the chemical amount of released hydrogen:
n (H2) = V (H2): Vm = 2.8: 22.4 = 0.125 mol;
3. Determine the amount of aluminum:
n (Al) = n (H2) * 2: 3 = 0.125 * 2: 3 = 0.0833 mol;
4. Let’s calculate the mass of aluminum:
m (Al) = n (Al) * M (Al) = 0.0833 * 27 = 2.25 g;
5. Find the mass fraction of aluminum in the mixture:
w (Al) = m (Al): m (mixtures) = 2.25: 10 = 0.225 or 22.5%.
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