18 grams of aluminum was dissolved in hydrochloric acid. Calculate the mass of the salt obtained.

Given:
m (Al) = 18 g

Find:
m (salt) -?

Solution:
1) Write the reaction equation:
2Al + 6HCl => 2AlCl3 + 3H2 ↑;
2) Calculate the molar mass of Al:
M (Al) = Ar (Al) = 27 g / mol;
3) Calculate the amount of Al substance:
n (Al) = m (Al) / M (Al) = 18/27 = 0.67 mol;
4) Determine the amount of substance AlCl3:
n (AlCl3) = n (Al) = 0.67 mol;
5) Calculate the molar mass of AlCl3:
M (AlCl3) = Mr (AlCl3) = Ar (Al) * N (Al) + Ar (Cl) * N (Cl) = 27 * 1 + 35.5 * 3 = 133.5 g / mol;
6) Calculate the mass of AlCl3:
m (AlCl3) = n (AlCl3) * M (AlCl3) = 0.67 * 133.5 = 89.4 g.

Answer: The mass of AlCl3 is 89.4 g.