Honors Chemistry worksheet with exercises on writing and balancing chemical equations and converting word equations to chemical equations.

You’ve uploaded a worksheet titled “Honors Chemistry – Writing and Balancing Equations Worksheet.” The visible part includes numbered chemical equations (12–21) that need to be balanced, followed by a section on “Word Equations” where you’re asked to convert word descriptions into balanced chemical equations.

Since the word equations section is blurred and unreadable, I will solve and explain only the numbered chemical equations 12 through 21 as requested. I’ll balance each one step-by-step and provide reasoning.

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🔢 Balancing Chemical Equations: Step-by-Step Solutions

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#### 12) ___ Na + ___ H₂O → ___ NaOH + ___ H₂

This is the reaction of sodium metal with water.

✔ Unbalanced:
Na + H₂O → NaOH + H₂

Step 1: Count atoms on each side.

Left: Na=1, H=2, O=1
Right: Na=1, O=1, H=1 (in NaOH) + 2 (in H₂) = 3 H — ✘ Not balanced.

Step 2: Try balancing H. Right has 3 H total (1 in NaOH, 2 in H₂). Left has 2 H per H₂O.

Try 2 NaOH → then we need 2 Na on left → now 2 Na, 2 O, 4 H on right? Wait — let’s try:

Put 2 Na on left → need 2 NaOH on right → now H: left = 2H per H₂O, right = 2H in 2NaOH + 2H in H₂ = 4H → so need 2 H₂O on left.

Let’s try:

2 Na + 2 H₂O → 2 NaOH + H₂

Check atoms:

Left: Na=2, H=4, O=2
Right: Na=2, O=2, H=2 (from 2NaOH) + 2 (from H₂) = 4 H ✔

✔️ Balanced Equation:
> 2 Na + 2 H₂O → 2 NaOH + H₂

*(Note: Some sources write it as 2Na + 2H₂O → 2NaOH + H₂ — this is correct.)*

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#### 13) ___ Ag₂O → ___ Ag + ___ O₂

Decomposition of silver(I) oxide.

✔ Unbalanced:
Ag₂O → Ag + O₂

Left: Ag=2, O=1
Right: Ag=1, O=2 — ✘

Step 1: Balance O first. Need 2 O on left → use 2 Ag₂O → gives 4 Ag and 2 O.

Now right: need O₂ (which has 2 O) → good. But Ag: 4 on left → need 4 Ag on right.

2 Ag₂O → 4 Ag + O₂

Check:

Left: Ag=4, O=2
Right: Ag=4, O=2 ✔

✔️ Balanced Equation:
> 2 Ag₂O → 4 Ag + O₂

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#### 14) ___ S₈ + ___ O₂ → ___ SO₃

Sulfur (S₈) burns to form sulfur trioxide.

✔ Unbalanced:
S₈ + O₂ → SO₃

Left: S=8, O=2
Right: S=1, O=3 — ✘

Step 1: Balance S. Put 8 SO₃ on right → 8 S and 24 O.

Left: S₈ gives 8 S → good. Now O: need 24 O → since O₂ has 2 O per molecule → need 12 O₂.

S₈ + 12 O₂ → 8 SO₃

Check:

Left: S=8, O=24
Right: S=8, O=24 ✔

✔️ Balanced Equation:
> S₈ + 12 O₂ → 8 SO₃

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#### 15) ___ CO₂ + ___ H₂O → ___ C₆H₁₂O₆ + ___ O₂

This is photosynthesis — carbon dioxide and water make glucose and oxygen.

✔ Unbalanced:
CO₂ + H₂O → C₆H₁₂O₆ + O₂

Left: C=1, O=3, H=2
Right: C=6, H=12, O=6+2=8 — ✘

Step 1: Balance C. Need 6 CO₂ → 6 C, 12 O.

Step 2: Balance H. Glucose has 12 H → need 6 H₂O → 12 H, 6 O.

Now left: C=6, H=12, O=12 (from CO₂) + 6 (from H₂O) = 18 O.

Right: Glucose has 6 O, plus O₂ has ? Let’s say x O₂ → 2x O.

Total O on right: 6 + 2x

Set equal: 6 + 2x = 18 → 2x = 12 → x = 6

So: 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

Check:

Left: C=6, H=12, O=12+6=18
Right: C=6, H=12, O=6 (glucose) + 12 (6 O₂) = 18 ✔

✔️ Balanced Equation:
> 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

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#### 16) ___ K + ___ MgBr₂ → ___ KBr + ___ Mg

Single replacement: Potassium replaces magnesium.

✔ Unbalanced:
K + MgBr₂ → KBr + Mg

Left: K=1, Mg=1, Br=2
Right: K=1, Br=1, Mg=1 — ✘ Br not balanced.

Need 2 KBr on right → then need 2 K on left.

2 K + MgBr₂ → 2 KBr + Mg

Check:

Left: K=2, Mg=1, Br=2
Right: K=2, Br=2, Mg=1 ✔

✔️ Balanced Equation:
> 2 K + MgBr₂ → 2 KBr + Mg

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#### 17) ___ HCl + ___ CaCO₃ → ___ CaCl₂ + ___ H₂O + ___ CO₂

Acid + carbonate → salt + water + CO₂

✔ Unbalanced:
HCl + CaCO₃ → CaCl₂ + H₂O + CO₂

Left: H=1, Cl=1, Ca=1, C=1, O=3
Right: Ca=1, Cl=2, H=2, O=1 (H₂O) + 2 (CO₂) = 3, C=1 — ✘ H and Cl not balanced.

CaCl₂ has 2 Cl → need 2 HCl on left.

Then H: 2 H on left → need 1 H₂O on right (has 2 H).

Check:

2 HCl + CaCO₃ → CaCl₂ + H₂O + CO₂

Left: H=2, Cl=2, Ca=1, C=1, O=3
Right: Ca=1, Cl=2, H=2, O=1+2=3, C=1 ✔

✔️ Balanced Equation:
> 2 HCl + CaCO₃ → CaCl₂ + H₂O + CO₂

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#### 18) ___ HNO₃ + ___ NaHCO₃ → ___ NaNO₃ + ___ H₂O + ___ CO₂

Acid + bicarbonate → salt + water + CO₂

✔ Unbalanced:
HNO₃ + NaHCO₃ → NaNO₃ + H₂O + CO₂

Left: H=1+1=2, N=1, O=3+3=6, Na=1, C=1
Right: Na=1, N=1, O=3 (NaNO₃) +1 (H₂O) +2 (CO₂)=6, H=2, C=1 ✔

Wait — actually, this is already balanced!

Check atom by atom:

Left: H=1 (HNO₃) +1 (NaHCO₃) = 2
Right: H=2 (H₂O) → ✔️

N: 1 = 1
Na: 1 = 1
C: 1 = 1
O: 3 (HNO₃) + 3 (NaHCO₃) = 6; Right: 3 (NaNO₃) + 1 (H₂O) + 2 (CO₂) = 6 ✔️

✔️ Balanced Equation:
> HNO₃ + NaHCO₃ → NaNO₃ + H₂O + CO₂

*(No coefficients needed — all are 1.)*

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#### 19) ___ H₂O + ___ O₂ → ___ H₂O₂

Formation of hydrogen peroxide from water and oxygen? This is not a typical reaction — in fact, it’s not spontaneous or common under normal conditions. Hydrogen peroxide decomposes to water and oxygen, not the reverse.

But if we’re just balancing as written:

✔ Unbalanced:
H₂O + O₂ → H₂O₂

Left: H=2, O=1+2=3
Right: H=2, O=2 — ✘

To balance O: Right has 2 O, left has 3 O — impossible with integer coefficients unless we allow fractions.

Try: 2 H₂O + O₂ → 2 H₂O₂

Left: H=4, O=2+2=4
Right: H=4, O=4 ✔

✔️ Balanced Equation:
> 2 H₂O + O₂ → 2 H₂O₂

*(Note: This reaction is not thermodynamically favorable under standard conditions — but for balancing purposes, it works.)*

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#### 20) ___ NaBr + ___ CaF₂ → ___ NaF + ___ CaBr₂

Double displacement reaction.

✔ Unbalanced:
NaBr + CaF₂ → NaF + CaBr₂

Left: Na=1, Br=1, Ca=1, F=2
Right: Na=1, F=1, Ca=1, Br=2 — ✘ F and Br not balanced.

CaBr₂ has 2 Br → need 2 NaBr on left → gives 2 Na, 2 Br.

Then NaF: need 2 NaF on right → 2 Na, 2 F.

Left: CaF₂ has 2 F → good.

2 NaBr + CaF₂ → 2 NaF + CaBr₂

Check:

Left: Na=2, Br=2, Ca=1, F=2
Right: Na=2, F=2, Ca=1, Br=2 ✔

✔️ Balanced Equation:
> 2 NaBr + CaF₂ → 2 NaF + CaBr₂

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#### 21) ___ H₂SO₄ + ___ NaNO₂ → ___ HNO₂ + ___ Na₂SO₄

Acid + salt → weak acid + salt (double displacement)

✔ Unbalanced:
H₂SO₄ + NaNO₂ → HNO₂ + Na₂SO₄

Left: H=2, S=1, O=4, Na=1, N=1
Right: H=1, N=1, O=2 (HNO₂) + 4 (Na₂SO₄) = 6, Na=2, S=1 — ✘ H, Na, O not balanced.

Na₂SO₄ has 2 Na → need 2 NaNO₂ on left → gives 2 Na, 2 N, 4 O.

H₂SO₄ has 2 H → need 2 HNO₂ on right → 2 H, 2 N, 4 O.

Now check O:

Left: H₂SO₄ (4 O) + 2 NaNO₂ (4 O) = 8 O
Right: 2 HNO₂ (4 O) + Na₂SO₄ (4 O) = 8 O ✔

H: 2 = 2
Na: 2 = 2
S: 1 = 1
N: 2 = 2

✔️ Balanced Equation:
> H₂SO₄ + 2 NaNO₂ → 2 HNO₂ + Na₂SO₄

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## ✔ Final Answer Summary (Balanced Equations):

12) 2 Na + 2 H₂O → 2 NaOH + H₂
13) 2 Ag₂O → 4 Ag + O₂
14) S₈ + 12 O₂ → 8 SO₃
15) 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂
16) 2 K + MgBr₂ → 2 KBr + Mg
17) 2 HCl + CaCO₃ → CaCl₂ + H₂O + CO₂
18) HNO₃ + NaHCO₃ → NaNO₃ + H₂O + CO₂
19) 2 H₂O + O₂ → 2 H₂O₂
20) 2 NaBr + CaF₂ → 2 NaF + CaBr₂
21) H₂SO₄ + 2 NaNO₂ → 2 HNO₂ + Na₂SO₄

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## 📝 Note on Word Equations Section:
The word equations below are blurred/unreadable in your image. If you can provide the text (by typing it out), I’d be happy to convert them to chemical equations and balance them too!

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Let me know if you want explanations for *why* these reactions occur or their types (synthesis, decomposition, single/double replacement, combustion, etc.)!