Molar Mass HW 5-2

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

Molar Mass

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 = 2.02 O: 1 x 16.00 = 16.00 H2O = 18.02 g/mole

5-2, #2 2) Molar Masses of a substance is calculated by ___________________ the atomic weights of the component atoms. ADDING

HW 5-2, #2 # 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

Since 6.022 x 1023 atoms = 1 mole, subscripts also represent the # of MOLES of that element present in 1 mole of compound.

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

Homework 5-2, #4 4A) NH4Br N: H: Br: 97.95 g/mole 1 x 14.01 g = 14.01 g 4 x 1.01 g = 4.04 g 1 x 79.90 g = 79.90 g 97.95 g/mole

HW 5-2 #4B 4B) Mg(NO2)2 Mg: N: O: 1 x 24.31 g = 24.31 g 116.33 g/mole

HW 5-2 #4C 4B) Ca3(PO4)2 310.18 g/mole Ca: P: 3 x 40.08 g = 120.24 g

HW 5-2, #5 O2 = 32.00 g/mole = Gas C SO2 = 64.07 g/mole = Gas A NH3 = 17.03 g/mole = Gas B NO2 = 46.00 g/mole

HW 5-2, #6 N = 14.00 O = 16.00 Compound X: 14.0 + 16.0 = 30.0 N O = NO Compound Y: 28.0 + 16.0 = 44.0 N2 O = N2O Compound Z: 14.0 + 32.0 = 46.0 N O2 = NO2