This chemistry worksheet helps students master fundamental concepts including filtration and distillation techniques, identifying physical versus chemical changes, and applying the Law of Definite Proportions.

1. a) Diagram A: Filtration. Diagram B: Distillation.
b) Filtration (Technique A) would be useful to separate sand and salt because sand is insoluble in water and can be filtered out, while salt dissolves.
c) Distillation (Technique B) would be useful to separate salt and water because it evaporates the water and condenses it back, leaving the salt behind.
d) Technique A (filtration) would not be effective for separating salt and sugar because both are soluble in water and will pass through the filter paper together.

2. a) Physical change – particles gain energy and move apart but remain the same substance.
b) Physical change – molecules mix but no new substances form.
c) Chemical change – heat causes reactions that break and form bonds, creating new substances.
d) Chemical change – acid-base reaction produces carbon dioxide gas and new compounds.
e) Physical change – particles gain kinetic energy and spread out but remain the same molecules.

3. Sample B: Mass Fe = 0.750 g, Mass Cl = 1.425 g
Sample C: Mass Iron Chloride = 3.813 g, Mass Cl = 1.801 g
Sample D: Mass Fe = 0.926 g, Mass Iron Chloride = 3.255 g

Work:
From Sample A: Mass Fe / Mass Cl = 1.302 / 2.483 ≈ 0.5244
Mass Fe / Mass Iron Chloride = 1.302 / 3.785 ≈ 0.3440
Mass Cl / Mass Iron Chloride = 2.483 / 3.785 ≈ 0.6560

Sample B:
Mass Fe = 2.175 g × 0.3440 = 0.750 g
Mass Cl = 2.175 g × 0.6560 = 1.425 g

Sample C:
Mass Iron Chloride = 2.012 g / 0.3440 = 3.813 g
Mass Cl = 3.813 g - 2.012 g = 1.801 g

Sample D:
Mass Fe = 2.329 g × (1.302 / 2.483) = 2.329 g × 0.5244 = 0.926 g
Mass Iron Chloride = 0.926 g + 2.329 g = 3.255 g