An aluminum plate weighing 10 g was placed in a solution of copper chloride (2).

An aluminum plate weighing 10 g was placed in a solution of copper chloride (2). The weight of the plate increased by 16.9 g. What mass of aluminum reacted?

Given:
m (plates) = 10 g
Δm (plates) = 16.9 g

To find:
m react. (Al) -?

Decision:
1) 2Al + 3CuCl2 => 2AlCl3 + 3Cu;
2) Let n react. (Al) = (x) mol;
3) n (Cu) = n reag. (Al) * 3/2 = (1.5x) mol;
4) m react. (Al) = n react. (Al) * M (Al) = (27x) g;
5) m (Cu) = n (Cu) * M (Cu) = (96x) g;
6) Δm (plates) = m (Cu) – m react. (Al);
16.9 = 96x – 27x;
x = 0.24;
7) m react. (Al) = 27x = 27 * 0.24 = 6.5 g.

Answer: The mass of Al is 6.5 g.