This document contains calculations for several chemistry problems involving molar mass, moles, mass, and molecules. It first calculates the moles and mass of water (H2O) given its mass. It then calculates the number of molecules in samples of hydrogen gas (H2), butane (C4H10), carbon monoxide (CO), and methane (CH4) using molar mass and moles. The final calculation determines the number of methane molecules produced in an hour given the moles produced over 5 hours.

3. EXERCÍCIOS
Pg. 102
Exercícios 1, 2 e 3

4. d = 1 g/mL --------------- > 1 mL ----------------- 1 g 180 mL ----------------- 180 g m = 180 g de água Massa Molar (M) da H2O = 2. 1 + 1. 16 = 18 g/ mol 1 mol ---------------- 18 g n = 180 = 10 mols n ---------------- 180 g 18 Ou: n = m = 180 g = 10 mols M 18 g/mol

5. Massa Molecular (MM) do H2 = 2 . 1 = 2 u
Massa Molar (M) = 2 g
2 g ---------------- 6,0 . 1023 moléculas
8 g ---------------- X
X = 8 . 6,0 . 1023 = 24 . 1023
2
X = 2,4 . 1024 moléculas

6. Massa Molar (M) do C4H10 = 4.12 + 10.1 = 58 g/ mol
58 g ----- 6,0 . 1023 moléculas ----- 14 (6,0 . 1023) átomos
23,2 g ------------------------------------ X
X = 23,2 . 14 (6,0 . 1023) = 33,6 . 1023
58
X = 3,36 . 1024 átomos

7. EXERCÍCIOS
Pg. 102
Exercícios 4 e 5

8. Massa Molar (M) do CO = 1 . 12 + 1 . 16 = 28 g/ mol
28 g ----------------- 6,0 . 1023 moléculas
X g ----------------- 1,8 . 1022 moléculas
X = 28 . 1,8 . 1022 = 8,4 . 10-1 g
6,0 . 1023
X = 0,84 gramas

9. Massa Molar (M) do CH4 = 1 . 12 + 4 . 1 = 16 g/ mol
1 kg = 1000 g, então 3,2 kg = 3200 g
1 mol ----------------- 16 g
n ------------------ 3200 g
n = 3200 =
16
X = 200 mols

10. 200 mol ----------------- 5 horas
n ------------------- 1 hora
n = 200 = 40 mols
5
1 mol ------------------- 6,0 . 1023 moléculas
40 mols ---------------- X moléculas
X = 40 (6,0 . 1023) = 240 . 1023 moléculas
= 2,4 . 1025 moléculas