Question

calculate the molar mass for each of the following molecules:

1. koh

k = 39.1
o = 16
h = 1.01

1. n₂o₂

n: 28
o: 32

1. cu₂so₄
2. sr₃(po₄)₂

convert each of the following from grams to moles:

1. 15.0 g c₂h₆
2. 140.0 g naoh
3. 27.2 g h₂o
4. 45.7 g caco₃
5. 450 grams of ncl₃
6. 215.8 grams of agcl

Explanation:

1. KOH Molar Mass

Sum K, O, H atomic masses: $39.1 + 16.0 + 1.01 = 56.11$ g/mol

2. N₂O₃ Molar Mass

Sum 2N + 3O: $2×14.0 + 3×16.0 = 76.0$ g/mol

3. Cu₂SO₄ Molar Mass

Sum 2Cu + S + 4O: $2×63.5 + 32.1 + 4×16.0 = 223.1$ g/mol

4. Sr₃(PO₄)₂ Molar Mass

Sum 3Sr + 2P + 8O: $3×87.6 + 2×31.0 + 8×16.0 = 452.8$ g/mol

5. 15.0 g C₂H₆ to Moles

Molar mass C₂H₆: $2×12.0 + 6×1.01 = 30.06$ g/mol; Moles: $15.0 / 30.06 ≈ 0.499$ mol

6. 140.0 g NaOH to Moles

Molar mass NaOH: $23.0 + 16.0 + 1.01 = 40.01$ g/mol; Moles: $140.0 / 40.01 ≈ 3.499$ mol

7. 27.2 g H₂O to Moles

Molar mass H₂O: $2×1.01 + 16.0 = 18.02$ g/mol; Moles: $27.2 / 18.02 ≈ 1.509$ mol

8. 45.7 g CaCO₃ to Moles

Molar mass CaCO₃: $40.1 + 12.0 + 3×16.0 = 100.1$ g/mol; Moles: $45.7 / 100.1 ≈ 0.456$ mol

9. 450 g NCl₃ to Moles

Molar mass NCl₃: $14.0 + 3×35.5 = 120.5$ g/mol; Moles: $450 / 120.5 ≈ 3.734$ mol

10. 215.8 g AgCl to Moles

Molar mass AgCl: $107.9 + 35.5 = 143.4$ g/mol; Moles: $215.8 / 143.4 ≈ 1.505$ mol

Answer:

1. 56.11 g/mol
2. 76.0 g/mol
3. 223.1 g/mol
4. 452.8 g/mol
5. 0.499 mol
6. 3.499 mol
7. 1.509 mol
8. 0.456 mol
9. 3.734 mol
10. 1.505 mol