Question

al + hcl → alcl₃ + h₂

Explanation:

Step1: Balance chlorine atoms

We have 1 chlorine in HCl and 3 in AlCl₃. The least - common multiple of 1 and 3 is 3. So we put a 3 in front of HCl to start balancing chlorine: Al + 3HCl → AlCl₃+H₂. But now we have 3 hydrogen atoms on the left - hand side and 2 on the right - hand side.

Step2: Balance hydrogen and aluminum atoms

To balance hydrogen, we need to make the number of hydrogen atoms equal on both sides. The least - common multiple of 2 and 3 is 6. So we change the coefficients to get 2Al+6HCl → 2AlCl₃ + 3H₂. Now, the number of aluminum atoms is 2 on both sides, the number of chlorine atoms is 6 on both sides, and the number of hydrogen atoms is 6 on both sides.

Answer:

2, 6, 2, 3