Mole Calculation Practice Worksheet featuring five questions on converting moles to grams and grams to moles for different chemical substances.

I'll solve each of these mole calculation problems step by step. Let me work through them carefully.

Problem 1: How many grams are in 4.5 moles of NaF?

First, I need to find the molar mass of NaF (sodium fluoride):
- Na (sodium) = 22.99 g/mol
- F (fluorine) = 19.00 g/mol
- Molar mass of NaF = 22.99 + 19.00 = 41.99 g/mol

Now convert moles to grams:
Mass = moles × molar mass
Mass = 4.5 mol × 41.99 g/mol = 188.955 g ≈ 189 g

Problem 2: How many moles are in 1.2 × 10³ grams of ammonia?

Ammonia is NH₃. First, find its molar mass:
- N (nitrogen) = 14.01 g/mol
- H (hydrogen) = 1.008 g/mol × 3 = 3.024 g/mol
- Molar mass of NH₃ = 14.01 + 3.024 = 17.034 g/mol

Convert grams to moles:
Moles = mass ÷ molar mass
Moles = 1200 g ÷ 17.034 g/mol = 70.45 mol ≈ 70 mol (or 7.0 × 10¹ mol)

Problem 3: How many grams are in 0.02 moles of beryllium iodide?

Beryllium iodide is BeI₂. Find its molar mass:
- Be (beryllium) = 9.01 g/mol
- I (iodine) = 126.90 g/mol × 2 = 253.80 g/mol
- Molar mass of BeI₂ = 9.01 + 253.80 = 262.81 g/mol

Convert moles to grams:
Mass = 0.02 mol × 262.81 g/mol = 5.2562 g ≈ 5.3 g

Problem 4: How many moles are in 98.3 grams of aluminum hydroxide?

Aluminum hydroxide is Al(OH)₃. Find its molar mass:
- Al (aluminum) = 26.98 g/mol
- O (oxygen) = 16.00 g/mol × 3 = 48.00 g/mol
- H (hydrogen) = 1.008 g/mol × 3 = 3.024 g/mol
- Molar mass of Al(OH)₃ = 26.98 + 48.00 + 3.024 = 78.004 g/mol

Convert grams to moles:
Moles = 98.3 g ÷ 78.004 g/mol = 1.260 mol ≈ 1.26 mol

Problem 5: How many grams are in 3.3 moles of potassium sulfide?

Potassium sulfide is K₂S. Find its molar mass:
- K (potassium) = 39.10 g/mol × 2 = 78.20 g/mol
- S (sulfur) = 32.07 g/mol
- Molar mass of K₂S = 78.20 + 32.07 = 110.27 g/mol

Convert moles to grams:
Mass = 3.3 mol × 110.27 g/mol = 363.891 g ≈ 364 g

Final Answer:
1. 189 g
2. 70 mol (or 7.0 × 10¹ mol)
3. 5.3 g
4. 1.26 mol
5. 364 g