A. 2Al(s) + 3Cl2(g) —> 2AlCl3(s)
B. 2Li(s) + 2H2O(l) —> 2LiOH(aq) + H2(g)
C. H2(g) + Br2(l) —> 2HBr(g)
Explanation:
A. Reaction between aluminium metal and chlorine gas.
Al(s) + Cl2(g) —> AlCl3(s)
The above equation can be balance as follow:
There are 2 atoms of Cl on the left side and 3 atoms on the right side. It can be balance by putting 3 in front of Cl2 and 2 in front of AlCl3 as shown below:
Al(s) + 3Cl2(g) —> 2AlCl3(s)
There are 2 atoms of Al on the right side and 1 atom on the left side. It can be balance by putting 2 in front of Al as shown below:
2Al(s) + 3Cl2(g) —> 2AlCl3(s)
Now the equation is balanced.
B. Reaction between lithium metal and liquid water.
Li(s) + H2O(l) —> LiOH(aq) + H2(g)
The above equation can be balance as follow:
There are 2 atoms of H on the left side and a total of 3 atoms on the right side. It can be balance by putting 2 in front of H2O and 2 in front of LiOH as shown below:
Li(s) + 2H2O(l) —> 2LiOH(aq) + H2(g)
There are 2 atoms of Li on the right side and 1 atom on the left side. It can be balance by putting 2 in front of Li as shown below:
2Li(s) + 2H2O(l) —> 2LiOH(aq) + H2(g)
Now, the equation is balanced.
C. Reaction between gaseous hydrogen and liquid bromine.
H2(g) + Br2(l) —> HBr(g)
The above equation can be balance as follow:
There are 2 atoms of H on the left side and 1 atom on the right. It can be balance by putting 2 in front of HBr as shown below:
H2(g) + Br2(l) —> 2HBr(g)
Now the equation is balanced.
