Chemistry worksheet featuring problems on mass conservation calculations and balancing chemical equations for high school students.

I'll solve this Law of Conservation of Mass worksheet step by step.

Part 1: Fill in the blank with the correct number

The Law of Conservation of Mass states that mass cannot be created or destroyed in a chemical reaction. This means:
Mass of reactants = Mass of products

Let me work through each problem:

1) 40 g calcium + 71 g chlorine → ? g calcium chloride
Mass of products = 40 + 71 = 111 g

2) ? g potassium + 16 g oxygen → 94 g potassium oxide
Mass of potassium = 94 - 16 = 78 g

3) 14 g lithium + ? g sulfur → 46 g lithium sulfide
Mass of sulfur = 46 - 14 = 32 g

4) 24 g magnesium + 38 g fluorine → ? g magnesium fluoride
Mass of products = 24 + 38 = 62 g

5) 65.5 g copper + ? g oxygen → 81 g copper (I) oxide
Mass of oxygen = 81 - 65.5 = 15.5 g

6) 88 g strontium + 160 g bromine → ? g strontium bromide
Mass of products = 88 + 160 = 248 g

7) 46 g sodium + ? g chlorine → 117 g sodium chloride
Mass of chlorine = 117 - 46 = 71 g

8) ? g iron + 71 g chlorine → 129 g iron (II) chloride
Mass of iron = 129 - 71 = 58 g

9) 137 g barium + ? g iodine → 391 g barium iodide
Mass of iodine = 391 - 137 = 254 g

10) ? g hydrogen + 32 g oxygen → 34 g hydrogen peroxide
Mass of hydrogen = 34 - 32 = 2 g

11) Why do we balance chemical reactions?
We balance chemical reactions to satisfy the Law of Conservation of Mass, ensuring the same number of atoms of each element on both sides of the equation.

Part 2: Identify the type of reaction and balance

A. NaOH + HCl → NaCl + H₂O
Type: Double replacement (or neutralization)
Already balanced: 1 NaOH + 1 HCl → 1 NaCl + 1 H₂O

B. H₂ + O₂ → H₂O
Type: Synthesis/Combination
Balanced: 2 H₂ + 1 O₂ → 2 H₂O

C. Cl₂ + NaBr → NaCl + Br₂
Type: Single replacement
Balanced: 1 Cl₂ + 2 NaBr → 2 NaCl + 1 Br₂

D. H₂O + Fe → Fe₂O₃ + H₂
Type: Single replacement
Balanced: 3 H₂O + 2 Fe → 1 Fe₂O₃ + 3 H₂

E. Na₂O + CO₂ → Na₂CO₃
Type: Synthesis/Combination
Already balanced: 1 Na₂O + 1 CO₂ → 1 Na₂CO₃

F. H₂ + N₂ → NH₃
Type: Synthesis/Combination
Balanced: 3 H₂ + 1 N₂ → 2 NH₃

G. Al₂O₃ + HCl → AlCl₃ + H₂O
Type: Double replacement
Balanced: 1 Al₂O₃ + 6 HCl → 2 AlCl₃ + 3 H₂O

H. Cl₂ + H₂O → HCl + O₂
Type: Single replacement
Balanced: 2 Cl₂ + 2 H₂O → 4 HCl + 1 O₂

──────────────────────────────────────

Final Answer:

Fill in the blanks:
1) 111
2) 78
3) 32
4) 62
5) 15.5
6) 248
7) 71
8) 58
9) 254
10) 2

11) We balance chemical reactions to satisfy the Law of Conservation of Mass, ensuring equal numbers of atoms on both sides.

Balance and identify types:
A. 1, 1, 1, 1 - Double replacement
B. 2, 1, 2 - Synthesis
C. 1, 2, 2, 1 - Single replacement
D. 3, 2, 1, 3 - Single replacement
E. 1, 1, 1 - Synthesis
F. 3, 1, 2 - Synthesis
G. 1, 6, 2, 3 - Double replacement
H. 2, 2, 4, 1 - Single replacement