Let’s go through each part of the worksheet step by step. We’ll check if the equations are balanced and confirm the reaction type.
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a) 2 NaBr + 1 Ca(OH)₂ → 1 CaBr₂ + 2 NaOH
- Left side:
Na = 2, Br = 2, Ca = 1, O = 2, H = 2
- Right side:
Ca = 1, Br = 2, Na = 2, O = 2, H = 2
✔ Balanced.
Type: Two compounds swap partners →
double displacement
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b) 2 NH₃ + 1 H₂SO₄ → 1 (NH₄)₂SO₄
- Left: N=2, H=6+2=8, S=1, O=4
- Right: N=2, H=8, S=1, O=4
✔ Balanced.
Type: Two things combine to make one →
synthesis
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c) 4 C₅H₉O + 27 O₂ → 20 CO₂ + 18 H₂O
Check atoms:
Left:
C = 4×5 = 20
H = 4×9 = 36
O = 4×1 + 27×2 = 4 + 54 = 58
Right:
C = 20×1 = 20
H = 18×2 = 36
O = 20×2 + 18×1 = 40 + 18 = 58
✔ Balanced.
Type: Hydrocarbon + oxygen → CO₂ + H₂O →
combustion
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d) 3 Pb + 2 H₃PO₄ → 3 H₂ + 1 Pb₃(PO)₂
Left:
Pb = 3
H = 2×3 = 6
P = 2×1 = 2
O = 2×4 = 8
Right:
H = 3×2 = 6
Pb = 3
P = 2 (from PO₄)
O = 8 (from 2 PO₄ groups)
✔ Balanced.
Type: Element replaces another in compound →
single displacement
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e) 1 Li₃N + 3 NH₄NO₃ → 3 LiNO₃ + 1 (NH₄)₃N
Left:
Li = 3
N = 1 + 3×2 = 7? Wait — let’s break it down carefully.
Li₃N has: Li=3, N=1
Each NH₄NO₃ has: N=2 (one in NH₄, one in NO₃), H=4, O=3
So 3 NH₄NO₃: N=6, H=12, O=9
Total left: Li=3, N=1+6=7, H=12, O=9
Right:
3 LiNO₃: Li=3, N=3, O=9
(NH₄)₃N: N=3+1=4? Wait — (NH₄)₃N means 3 NH₄⁺ and 1 N³⁻ → total N = 3 + 1 = 4
H = 3×4 = 12
So right: Li=3, N=3+4=7, H=12, O=9
✔ Balanced.
Type: Ions swap between two compounds →
double displacement
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f) 3 HBr + 1 Al(OH)₃ → 3 H₂O + 1 AlBr₃
Left:
H = 3×1 + 1×3 = 6
Br = 3
Al = 1
O = 3
Right:
H = 3×2 = 6
O = 3
Al = 1
Br = 3
✔ Balanced.
Type: Acid + base → water + salt →
acid-base
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g) What’s the main difference between a double displacement reaction and an acid-base reaction?
Double displacement: any two compounds swap ions. Could form precipitate, gas, or water.
Acid-base: special case where acid + base → water + salt. Always forms water.
So key difference:
Acid-base reactions always produce water.
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h) Complete combustion reactions always result in the formation of water. What other types of chemical reaction may result in the formation of water?
Yes — acid-base reactions also form water.
Example given: HCl + NaOH → H₂O + NaCl
✔
Other possibilities? Sometimes synthesis (like H₂ + O₂ → H₂O), but that’s not common in basic worksheets. The expected answer here is
acid-base.
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Final Answer:
a) Balanced; double displacement
b) Balanced; synthesis
c) Balanced; combustion
d) Balanced; single displacement
e) Balanced; double displacement
f) Balanced; acid-base
g) Acid-base reactions form water.
h) Acid-base: HCl + NaOH → H₂O + NaCl
Parent Tip: Review the logic above to help your child master the concept of six types of chemical reactions worksheet.
