Worksheet for balancing chemical equations with 20 problems.
A worksheet titled "Practice: Balancing Equations #3" with 20 chemical equations to balance, including reactants and products with blank spaces for coefficients. Instructions at the top state to show work on a separate sheet and place final answers in the blanks. The page is numbered 11 and includes a copyright notice "© It's Not Rocket Science 2017" at the bottom.
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Show Answer Key & Explanations
Step-by-step solution for: Grade 9 Physical Science: Chemical Reactions] Balancing equations ...
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Show Answer Key & Explanations
Step-by-step solution for: Grade 9 Physical Science: Chemical Reactions] Balancing equations ...
Let’s go through each equation one by one and balance them. We’ll make sure the number of atoms of each element is the same on both sides.
---
1. Na₃PO₄ + KOH → NaOH + K₃PO₄
Left: Na=3, P=1, O=4+1=5, K=1, H=1
Right: Na=1, O=1+4=5, H=1, K=3, P=1
We need 3 Na on right → put 3 in front of NaOH
Now right has 3 Na, 3 O from NaOH + 4 from K₃PO₄ = 7 O? Wait — let’s recount carefully.
Actually, better to balance polyatomic ions as groups if they stay together.
PO₄ stays together → so we can treat PO₄ as a unit.
Na₃PO₄ has 3 Na and 1 PO₄
K₃PO₄ has 3 K and 1 PO₄ → so we need 3 K on left → put 3 in front of KOH
Then left: 3 K, 3 O, 3 H from KOH + Na₃PO₄
Right: need 3 Na → 3 NaOH → that gives 3 Na, 3 O, 3 H
Check:
Left: Na=3, P=1, O=4 (from PO₄) + 3 (from 3 OH) = 7, K=3, H=3
Right: Na=3, O=3 (from 3 OH) + 4 (from PO₄) = 7, H=3, K=3, P=1 → Balanced!
✔ Answer: 1, 3, 3, 1
---
2. MgF₂ + Li₂CO₃ → MgCO₃ + LiF
Left: Mg=1, F=2, Li=2, C=1, O=3
Right: Mg=1, C=1, O=3, Li=1, F=1
Need 2 Li and 2 F on right → put 2 in front of LiF
✔ Answer: 1, 1, 1, 2
---
3. P₄ + O₂ → P₂O₃
Left: P=4, O=2
Right: P=2, O=3
To get 4 P on right → put 2 in front of P₂O₃ → now P=4, O=6
So need 6 O on left → O₂ → 3 O₂ gives 6 O
✔ Answer: 1, 3, 2
---
4. RbNO₃ + BeF₂ → Be(NO₃)₂ + RbF
Left: Rb=1, N=1, O=3, Be=1, F=2
Right: Be=1, N=2, O=6, Rb=1, F=1
Need 2 NO₃ on left → put 2 in front of RbNO₃ → now Rb=2, N=2, O=6
Then right needs 2 RbF → so Rb=2, F=2
Left F=2 → good
✔ Answer: 2, 1, 1, 2
---
5. AgNO₃ + Cu → Cu(NO₃)₂ + Ag
Left: Ag=1, N=1, O=3, Cu=1
Right: Cu=1, N=2, O=6, Ag=1
Need 2 NO₃ on left → 2 AgNO₃ → then Ag=2
So right needs 2 Ag
✔ Answer: 2, 1, 1, 2
---
6. CF₄ + Br₂ → CBr₄ + F₂
Left: C=1, F=4, Br=2
Right: C=1, Br=4, F=2
Need 4 Br on left → 2 Br₂ → Br=4
Need 4 F on right → 2 F₂ → F=4
✔ Answer: 1, 2, 1, 2
---
7. HCN + CuSO₄ → H₂SO₄ + Cu(CN)₂
Left: H=1, C=1, N=1, Cu=1, S=1, O=4
Right: H=2, S=1, O=4, Cu=1, C=2, N=2
Need 2 HCN on left → H=2, C=2, N=2
Then right Cu(CN)₂ already has Cu=1, C=2, N=2 → good
H₂SO₄ has H=2 → matches
✔ Answer: 2, 1, 1, 1
---
8. GaF₃ + Cs → CsF + Ga
Left: Ga=1, F=3, Cs=1
Right: Cs=1, F=1, Ga=1
Need 3 F on right → 3 CsF → then Cs=3
So left needs 3 Cs
✔ Answer: 1, 3, 3, 1
---
9. BaS + PtF₂ → BaF₂ + PtS
Left: Ba=1, S=1, Pt=1, F=2
Right: Ba=1, F=2, Pt=1, S=1 → Already balanced!
✔ Answer: 1, 1, 1, 1
---
10. N₂ + H₂ → NH₃
Left: N=2, H=2
Right: N=1, H=3
Put 2 in front of NH₃ → N=2, H=6
Then need 3 H₂ on left → H=6
✔ Answer: 1, 3, 2
---
11. NaF + Br₂ → NaBr + F₂
Left: Na=1, F=1, Br=2
Right: Na=1, Br=1, F=2
Need 2 NaF on left → Na=2, F=2
Then right needs 2 NaBr → Na=2, Br=2
But Br₂ only gives 2 Br → so 2 NaBr uses 2 Br → good
F₂ on right → F=2 → matches
Wait: Left: 2 NaF → F=2; Br₂ → Br=2
Right: 2 NaBr → Na=2, Br=2; F₂ → F=2 → yes!
✔ Answer: 2, 1, 2, 1
---
12. Pb(OH)₂ + HCl → H₂O + PbCl₂
Left: Pb=1, O=2, H=2+1=3, Cl=1
Right: H=2, O=1, Pb=1, Cl=2
Need 2 Cl on left → 2 HCl → H=2+2=4? Wait:
Pb(OH)₂ has 2 OH → so 2 O and 2 H
Plus 2 HCl → 2 H and 2 Cl → total H=4, O=2, Cl=2, Pb=1
Right: PbCl₂ → Pb=1, Cl=2
H₂O → need 2 H₂O to get H=4, O=2
✔ Answer: 1, 2, 2, 1
---
13. AlBr₃ + K₂SO₄ → KBr + Al₂(SO₄)₃
Left: Al=1, Br=3, K=2, S=1, O=4
Right: K=1, Br=1, Al=2, S=3, O=12
Need 2 Al on left → 2 AlBr₃ → Al=2, Br=6
Need 3 SO₄ on left → 3 K₂SO₄ → K=6, S=3, O=12
Right: Al₂(SO₄)₃ → Al=2, S=3, O=12
KBr → need 6 KBr → K=6, Br=6
✔ Answer: 2, 3, 6, 1
---
14. CH₄ + O₂ → CO₂ + H₂O
Left: C=1, H=4, O=2
Right: C=1, O=2+1=3? Wait: CO₂ has 2 O, H₂O has 1 O → total 3 O? But H=2
Need 2 H₂O → H=4, O=2 from H₂O + 2 from CO₂ = 4 O
So need 2 O₂ on left → O=4
✔ Answer: 1, 2, 1, 2
---
15. Na₃PO₄ + CaCl₂ → NaCl + Ca₃(PO₄)₂
Left: Na=3, P=1, O=4, Ca=1, Cl=2
Right: Na=1, Cl=1, Ca=3, P=2, O=8
Need 2 PO₄ on left → 2 Na₃PO₄ → Na=6, P=2, O=8
Need 3 Ca on left → 3 CaCl₂ → Ca=3, Cl=6
Right: Ca₃(PO₄)₂ → Ca=3, P=2, O=8
NaCl → need 6 NaCl → Na=6, Cl=6
✔ Answer: 2, 3, 6, 1
---
16. K + Cl₂ → KCl
Left: K=1, Cl=2
Right: K=1, Cl=1
Need 2 KCl → K=2, Cl=2
So 2 K on left
✔ Answer: 2, 1, 2
---
17. Al + HCl → H₂ + AlCl₃
Left: Al=1, H=1, Cl=1
Right: H=2, Al=1, Cl=3
Need 3 Cl on left → 3 HCl → H=3, Cl=3
But right H₂ → need even H → so double everything?
Try: 2 Al + 6 HCl → 3 H₂ + 2 AlCl₃
Check: Left: Al=2, H=6, Cl=6
Right: H=6, Al=2, Cl=6 → good
✔ Answer: 2, 6, 3, 2
---
18. N₂ + F₂ → NF₃
Left: N=2, F=2
Right: N=1, F=3
Need 2 NF₃ → N=2, F=6
So need 3 F₂ → F=6
✔ Answer: 1, 3, 2
---
19. SO₂ + Li₂Se → SSe₂ + Li₂O
Left: S=1, O=2, Li=2, Se=1
Right: S=1, Se=2, Li=2, O=1
Need 2 Se on left → 2 Li₂Se → Li=4, Se=2
Then right SSe₂ → S=1, Se=2 → good
Li₂O → need 2 Li₂O → Li=4, O=2 → matches left O=2
Left: SO₂ → S=1, O=2; 2 Li₂Se → Li=4, Se=2
Right: SSe₂ → S=1, Se=2; 2 Li₂O → Li=4, O=2 → perfect
✔ Answer: 1, 2, 1, 2
---
20. NH₃ + H₂SO₄ → (NH₄)₂SO₄
Left: N=1, H=3+2=5, S=1, O=4
Right: N=2, H=8, S=1, O=4
Need 2 NH₃ → N=2, H=6
Plus H₂SO₄ → H=2 → total H=8 → matches right (NH₄)₂ has 8 H
✔ Answer: 2, 1, 1
---
Final Answer:
1. 1, 3, 3, 1
2. 1, 1, 1, 2
3. 1, 3, 2
4. 2, 1, 1, 2
5. 2, 1, 1, 2
6. 1, 2, 1, 2
7. 2, 1, 1, 1
8. 1, 3, 3, 1
9. 1, 1, 1, 1
10. 1, 3, 2
11. 2, 1, 2, 1
12. 1, 2, 2, 1
13. 2, 3, 6, 1
14. 1, 2, 1, 2
15. 2, 3, 6, 1
16. 2, 1, 2
17. 2, 6, 3, 2
18. 1, 3, 2
19. 1, 2, 1, 2
20. 2, 1, 1
---
1. Na₃PO₄ + KOH → NaOH + K₃PO₄
Left: Na=3, P=1, O=4+1=5, K=1, H=1
Right: Na=1, O=1+4=5, H=1, K=3, P=1
We need 3 Na on right → put 3 in front of NaOH
Now right has 3 Na, 3 O from NaOH + 4 from K₃PO₄ = 7 O? Wait — let’s recount carefully.
Actually, better to balance polyatomic ions as groups if they stay together.
PO₄ stays together → so we can treat PO₄ as a unit.
Na₃PO₄ has 3 Na and 1 PO₄
K₃PO₄ has 3 K and 1 PO₄ → so we need 3 K on left → put 3 in front of KOH
Then left: 3 K, 3 O, 3 H from KOH + Na₃PO₄
Right: need 3 Na → 3 NaOH → that gives 3 Na, 3 O, 3 H
Check:
Left: Na=3, P=1, O=4 (from PO₄) + 3 (from 3 OH) = 7, K=3, H=3
Right: Na=3, O=3 (from 3 OH) + 4 (from PO₄) = 7, H=3, K=3, P=1 → Balanced!
✔ Answer: 1, 3, 3, 1
---
2. MgF₂ + Li₂CO₃ → MgCO₃ + LiF
Left: Mg=1, F=2, Li=2, C=1, O=3
Right: Mg=1, C=1, O=3, Li=1, F=1
Need 2 Li and 2 F on right → put 2 in front of LiF
✔ Answer: 1, 1, 1, 2
---
3. P₄ + O₂ → P₂O₃
Left: P=4, O=2
Right: P=2, O=3
To get 4 P on right → put 2 in front of P₂O₃ → now P=4, O=6
So need 6 O on left → O₂ → 3 O₂ gives 6 O
✔ Answer: 1, 3, 2
---
4. RbNO₃ + BeF₂ → Be(NO₃)₂ + RbF
Left: Rb=1, N=1, O=3, Be=1, F=2
Right: Be=1, N=2, O=6, Rb=1, F=1
Need 2 NO₃ on left → put 2 in front of RbNO₃ → now Rb=2, N=2, O=6
Then right needs 2 RbF → so Rb=2, F=2
Left F=2 → good
✔ Answer: 2, 1, 1, 2
---
5. AgNO₃ + Cu → Cu(NO₃)₂ + Ag
Left: Ag=1, N=1, O=3, Cu=1
Right: Cu=1, N=2, O=6, Ag=1
Need 2 NO₃ on left → 2 AgNO₃ → then Ag=2
So right needs 2 Ag
✔ Answer: 2, 1, 1, 2
---
6. CF₄ + Br₂ → CBr₄ + F₂
Left: C=1, F=4, Br=2
Right: C=1, Br=4, F=2
Need 4 Br on left → 2 Br₂ → Br=4
Need 4 F on right → 2 F₂ → F=4
✔ Answer: 1, 2, 1, 2
---
7. HCN + CuSO₄ → H₂SO₄ + Cu(CN)₂
Left: H=1, C=1, N=1, Cu=1, S=1, O=4
Right: H=2, S=1, O=4, Cu=1, C=2, N=2
Need 2 HCN on left → H=2, C=2, N=2
Then right Cu(CN)₂ already has Cu=1, C=2, N=2 → good
H₂SO₄ has H=2 → matches
✔ Answer: 2, 1, 1, 1
---
8. GaF₃ + Cs → CsF + Ga
Left: Ga=1, F=3, Cs=1
Right: Cs=1, F=1, Ga=1
Need 3 F on right → 3 CsF → then Cs=3
So left needs 3 Cs
✔ Answer: 1, 3, 3, 1
---
9. BaS + PtF₂ → BaF₂ + PtS
Left: Ba=1, S=1, Pt=1, F=2
Right: Ba=1, F=2, Pt=1, S=1 → Already balanced!
✔ Answer: 1, 1, 1, 1
---
10. N₂ + H₂ → NH₃
Left: N=2, H=2
Right: N=1, H=3
Put 2 in front of NH₃ → N=2, H=6
Then need 3 H₂ on left → H=6
✔ Answer: 1, 3, 2
---
11. NaF + Br₂ → NaBr + F₂
Left: Na=1, F=1, Br=2
Right: Na=1, Br=1, F=2
Need 2 NaF on left → Na=2, F=2
Then right needs 2 NaBr → Na=2, Br=2
But Br₂ only gives 2 Br → so 2 NaBr uses 2 Br → good
F₂ on right → F=2 → matches
Wait: Left: 2 NaF → F=2; Br₂ → Br=2
Right: 2 NaBr → Na=2, Br=2; F₂ → F=2 → yes!
✔ Answer: 2, 1, 2, 1
---
12. Pb(OH)₂ + HCl → H₂O + PbCl₂
Left: Pb=1, O=2, H=2+1=3, Cl=1
Right: H=2, O=1, Pb=1, Cl=2
Need 2 Cl on left → 2 HCl → H=2+2=4? Wait:
Pb(OH)₂ has 2 OH → so 2 O and 2 H
Plus 2 HCl → 2 H and 2 Cl → total H=4, O=2, Cl=2, Pb=1
Right: PbCl₂ → Pb=1, Cl=2
H₂O → need 2 H₂O to get H=4, O=2
✔ Answer: 1, 2, 2, 1
---
13. AlBr₃ + K₂SO₄ → KBr + Al₂(SO₄)₃
Left: Al=1, Br=3, K=2, S=1, O=4
Right: K=1, Br=1, Al=2, S=3, O=12
Need 2 Al on left → 2 AlBr₃ → Al=2, Br=6
Need 3 SO₄ on left → 3 K₂SO₄ → K=6, S=3, O=12
Right: Al₂(SO₄)₃ → Al=2, S=3, O=12
KBr → need 6 KBr → K=6, Br=6
✔ Answer: 2, 3, 6, 1
---
14. CH₄ + O₂ → CO₂ + H₂O
Left: C=1, H=4, O=2
Right: C=1, O=2+1=3? Wait: CO₂ has 2 O, H₂O has 1 O → total 3 O? But H=2
Need 2 H₂O → H=4, O=2 from H₂O + 2 from CO₂ = 4 O
So need 2 O₂ on left → O=4
✔ Answer: 1, 2, 1, 2
---
15. Na₃PO₄ + CaCl₂ → NaCl + Ca₃(PO₄)₂
Left: Na=3, P=1, O=4, Ca=1, Cl=2
Right: Na=1, Cl=1, Ca=3, P=2, O=8
Need 2 PO₄ on left → 2 Na₃PO₄ → Na=6, P=2, O=8
Need 3 Ca on left → 3 CaCl₂ → Ca=3, Cl=6
Right: Ca₃(PO₄)₂ → Ca=3, P=2, O=8
NaCl → need 6 NaCl → Na=6, Cl=6
✔ Answer: 2, 3, 6, 1
---
16. K + Cl₂ → KCl
Left: K=1, Cl=2
Right: K=1, Cl=1
Need 2 KCl → K=2, Cl=2
So 2 K on left
✔ Answer: 2, 1, 2
---
17. Al + HCl → H₂ + AlCl₃
Left: Al=1, H=1, Cl=1
Right: H=2, Al=1, Cl=3
Need 3 Cl on left → 3 HCl → H=3, Cl=3
But right H₂ → need even H → so double everything?
Try: 2 Al + 6 HCl → 3 H₂ + 2 AlCl₃
Check: Left: Al=2, H=6, Cl=6
Right: H=6, Al=2, Cl=6 → good
✔ Answer: 2, 6, 3, 2
---
18. N₂ + F₂ → NF₃
Left: N=2, F=2
Right: N=1, F=3
Need 2 NF₃ → N=2, F=6
So need 3 F₂ → F=6
✔ Answer: 1, 3, 2
---
19. SO₂ + Li₂Se → SSe₂ + Li₂O
Left: S=1, O=2, Li=2, Se=1
Right: S=1, Se=2, Li=2, O=1
Need 2 Se on left → 2 Li₂Se → Li=4, Se=2
Then right SSe₂ → S=1, Se=2 → good
Li₂O → need 2 Li₂O → Li=4, O=2 → matches left O=2
Left: SO₂ → S=1, O=2; 2 Li₂Se → Li=4, Se=2
Right: SSe₂ → S=1, Se=2; 2 Li₂O → Li=4, O=2 → perfect
✔ Answer: 1, 2, 1, 2
---
20. NH₃ + H₂SO₄ → (NH₄)₂SO₄
Left: N=1, H=3+2=5, S=1, O=4
Right: N=2, H=8, S=1, O=4
Need 2 NH₃ → N=2, H=6
Plus H₂SO₄ → H=2 → total H=8 → matches right (NH₄)₂ has 8 H
✔ Answer: 2, 1, 1
---
Final Answer:
1. 1, 3, 3, 1
2. 1, 1, 1, 2
3. 1, 3, 2
4. 2, 1, 1, 2
5. 2, 1, 1, 2
6. 1, 2, 1, 2
7. 2, 1, 1, 1
8. 1, 3, 3, 1
9. 1, 1, 1, 1
10. 1, 3, 2
11. 2, 1, 2, 1
12. 1, 2, 2, 1
13. 2, 3, 6, 1
14. 1, 2, 1, 2
15. 2, 3, 6, 1
16. 2, 1, 2
17. 2, 6, 3, 2
18. 1, 3, 2
19. 1, 2, 1, 2
20. 2, 1, 1
Parent Tip: Review the logic above to help your child master the concept of balanced and unbalanced chemical equations worksheet.
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