1. Molar Mass
HW 5-2

2. What is the mass of 1 mole of Helium? What is mass of 1 mole of Bromine?
6.022 x 1023 atoms of He
6.022 x 1023 molecules of bromine (Br2)
4.00 g He
159.8 g Br2

3. Molar Mass

4. 5-2, #2 , p.108
The molar mass of a substance is calculated by the atomic weights of the component atoms.
ADDING

5. HW 5-2:What is the mass of 1 mole of water, H2O?
Molar Mass of a compound =sum of masses of elements in formula
H: 2 x 1.01 =
O: 1 x = 16.00
H2O = g/mole

6. HW 5-2, #4
# of H2O molecules
Total # H atoms
Total #O atoms 1 2 10
100
6.022 x 1023 4 2 20 10
200
100
2(6.022 x 1023)
6.022 x 1023

7. Since x 1023 atoms = 1 mole, subscripts also represent the # of MOLES of that element present in 1 mole of compound.

8. 5-2, #5 1 1 28.00 32.00 44.00 Formula Mass in grams 6.022 x 1023 1
moles
Number of molecules
Formula
Mass in grams
6.022 x 1023 H2
2.02 N2 1 O2
CO2 1 1 1
28.00
6.022 x 1023
32.00
6.022 x 1023
44.00

9. Homework 5-2, #6 6A) NH4Br N: H: Br: 97.95 g/mole
1 x g = g
4 x g = 4.04 g
1 x g = g
97.95 g/mole

10. HW 5-2 #6B 6B) Mg(NO2)2 Mg: N: O: 1 x 24.31 g = 24.31 g
g/mole

11. HW 5-2, #6C 6C) Ca3(PO4)2 310.18 g/mole Ca: P: 3 x 40.08 g = 120.24 g

12. HW 5-2, #7 O2 = 32.00 g/mole = Gas C SO2 = 64.07 g/mole = Gas A
NH3 = g/mole = Gas B
NO2 = g/mole

13. HW 5-2, #8 N = 14.00 O = 16.00 Compound X: 14.0 + 16.0 = 30.0 N O = NO
Compound Y: = 44.0
N O = N2O
Compound Z: = 46.0
N O2 = NO2