Answer: See below
Explanation:
To balance equations, you want to have the same amount of elements on the product and reactants side.
__Al+ __HCl→__AlCl₃+ __H₂
We see that there are 3 Cl on the products side and 1 on the reactants side, but there are 2 H on the product and 1 on reactant. To fulfill them both, let's put a 6 at HCl.
__Al+ 6HCl→__AlCl₃+ __H₂
Now that we have a 6 at HCl, we can fill in AlCl₃ and H₂.
__Al+ 6HCl→ 2AlCl₃+ 3H₂
All we have left is to fill in Al.
2Al+ 6HCl→ 2AlCl₃+ 3H₂
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__NaCl→ __Na+ __Cl₂
Since we have 2 Cl on the products, we must put 2 on the reactants.
2NaCl→ __Na+ 1Cl₂
With 2 NaCl, we can fill in Na.
2NaCl→ 2Na+ 1Cl₂
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__Na₂S+ __HCl→ __NaCl+ __H₂S
We see 2 Na on reactants, so we can put 2 on the products.
__Na₂S+ __HCl→ 2NaCl+ __H₂S
With 2 H and 2 Cl on the products, we can put a 2 at HCl.
1Na₂S+ 2HCl→ 2NaCl+ 1H₂S
