Balancing Chemical Equations
Let’s balance each equation step-by-step.
Question 14: KHCO3 -> K2CO3 + H2O + CO2
Step 1: Write the unbalanced equation:
KHCO3→K2CO3+H2O+CO2
Step 2: Count atoms on both sides:
- Left: K=1, H=1, C=1, O=3
- Right: K=2, H=2 (in H2O), C=2 (1 in K2CO3 and 1 in CO2), O=6 (3 in K2CO3 + 1 in H2O + 2 in CO2)
Step 3: Balance potassium (K):
- Put 2 in front of KHCO3:
2KHCO3→K2CO3+H2O+CO2
Step 4: Check atoms again:
- Left: K=2, H=2, C=2, O=6
- Right: K=2, H=2, C=2, O=6
All atoms are balanced.
Balanced equation:
2KHCO3→K2CO3+H2O+CO2
Question 15: K + O2 -> K2O + C
Step 1: Write the unbalanced equation:
K+O2→K2O+C
Step 2: Carbon (C) appears only on the product side but not on the reactant side. This suggests carbon cannot be formed from K and O2 alone.
Conclusion: This equation is incorrect or incomplete because carbon cannot be produced from potassium and oxygen.
Corrected equation: If carbon is not involved, the reaction is:
4K+O2→2K2O
If carbon is involved, more information is needed.
Question 16: Ca(OH)2 + HNO3 -> Ca(NO3)2 + H2O
Step 1: Write the unbalanced equation:
Ca(OH)2+HNO3→Ca(NO3)2+H2O
Step 2: Balance calcium (Ca):
- 1 Ca on both sides, balanced.
Step 3: Balance nitrate (NO3):
- Left has 1 NO3 per HNO3, right has 2 NO3 in Ca(NO3)2.
- Put 2 in front of HNO3:
Ca(OH)2+2HNO3→Ca(NO3)2+H2O
Step 4: Balance hydrogen and oxygen:
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Left: H = 2 (in Ca(OH)2) + 2 (in 2 HNO3) = 4
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Right: H = 2 (in H2O)
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Oxygen is balanced as well.
Step 5: Balance water:
- Put 2 in front of H2O:
Ca(OH)2+2HNO3→Ca(NO3)2+2H2O
Step 6: Check atoms:
- Ca: 1 both sides
- H: Left 2 + 21=4, Right 22=4
- N: Left 2, Right 2
- O: Left (21) + (23) = 2 + 6 = 8, Right (23) + (21) = 6 + 2 = 8
All balanced.
Balanced equation:
Ca(OH)2+2HNO3→Ca(NO3)2+2H2O
Question 17: KH + H2O -> KOH + H2
Step 1: Write the unbalanced equation:
KH+H2O→KOH+H2
Step 2: Check atoms:
- K: 1 both sides
- H: Left 1 (in KH) + 2 (in H2O) = 3, Right 1 (in KOH) + 2 (in H2) = 3
- O: 1 both sides
Step 3: All atoms are balanced.
Balanced equation:
KH+H2O→KOH+H2
