Complete the following equations and balance them:
(i) Ca(s) + H2O(l) → (ii) Al(s) + HCl(aq) →
Answers
Answer:
i) 2Ca(s) + 2H2O(l) → 2CaOH(s) + H2(g)
ii) 2Al(s) + 6HCl(aq) → 2AlCl3(l) + 3H2(g)
Explanation:
i) Initial equation is
Ca + H2O → CaOH + H2
To balance the equation, we calculate the no. of elements on the R.H.S
H = 3
Ca = 1
O = 1
Whereas on the L.H.S
H = 2
Ca = 1
O = 1
We have to balance the no. of elements in the R.H.S and L.H.S
We need 1 more Hydrogen on the left to balance Hydrogen atom, so we put the co-efficient 2 in H2O to get another H2O molecule.
Ca + 2H2O → CaOH + H2
Consequently if we want to pair Ca & OH we have to put 2 as coefficient in Ca, so that we can get 2 molecules of CaOH.
2Ca + 2H2O → 2CaOH + H2
Now, on L.H.S, we have 4 molecules of Hydrogen whereas on R.H.S We have used 2 Hydrogen in CaOH and 2 in Hydrogen gas. Hence the Hydrogen is balanced.
You can also check the balance of the elements using a table :
LHS RHS
H 4 4
Ca 2 2
O 2 2
Therefore, the final balanced equation is
2Ca(s) + 2H2O(l) → 2CaOH(s) + H2(g)
ii) Likewise in the next one, our equation to be balanced is
Al + HCl → AlCl3 + H2
LHS : Al = 3
Cl = 1
H = 1
RHS : Al = 1
Cl = 3
H = 2
Step -1 : To balance Chlorine(Cl) on the L.H.S, we put the coefficient as 3 on the HCl atom.
Al + 3HCl → AlCl3 + H2
Step-2 : As a result, the no. of Hydrogen atom also increased by 2. Now, we have 3 H atoms on L.H.S & 2 H atoms on R.H.S. In order to get H2 as the product, we put 3 as the coefficient in H2 on the R.H.S
Al + 3HCl → AlCl3 + 3H2
Step-3 : Since we have 6 H atoms on R.H.S, we put 6 on the L.H.S too.
Al + 6HCl → AlCl3 + 3H2
Hence, H atom is balanced. But it increased the Cl atoms too.
Step-4 : To balance Cl on R.H.S, we put 2 as the coefficient of Al, in order to get 2 molecules of AlCl3.
2Al + 6HCl → 2AlCl3 + 3H2
Therefore the second equation is also balanced.
I tried to explain the best I could. Hope it helped you. :)
(i) Ca(s) + H2O(l) → Ca(OH)2
(ii) Al(s) + HCl(aq) → AlCl3 + H2
✳️ HOPE IT HELP YOU✳️