# Molar mass 2jvv97p - PowerPoint

### Pages to are hidden for

"Molar mass 2jvv97p - PowerPoint"

```					Molar mass
Gram atomic mass
 The mass, in grams, of 1 mole of an atom is equal to its
atomic mass.
 Use the periodic table to find out
 1 mol of Carbon is 12.0g
 1 mol of Nickel is 58.7g
Gram Molecular Mass and
Gram Formula Mass
= Molecular Mass

 Gram molar mass. The mass of one mole of a molecule is
equal to the sum of the mass of the atoms in the molecule.
 Gram formula mass. The mass of one mole of an ionic
compound is equal to the sum of the mass of the atoms in the
representative formula
 The term Molar Mass can be used to refer to the mass of 1
Mol of any element or compound
Lets practice!
 Question 12 p. 150
 Question 13 p. 151
 Question 14 p.153
Mole – Mass conversion
 The Molar Mass can be used as a conversion factor to convert
grams of a substance into moles of that substance
Lets work that through…
 Lets imagine we have 7.20 moles of the compound
dinitrogen trioxide. How much does that weigh?
   First, lets work out the molecular mass of one mole of
dinitrogen trioxide (N2O3)
   2 mol N x 14.0 g N/1 mol N = 28.0g N
   3 mol O x 16.0 g O/1 mol O = 48g O
   1 mol of N2O3 = 28.0 + 48.0 = 76.0 g N2O3
 Our conversion factor is:
 1 mol N2O3 = 76.0g of N2O3
 Or 1 mol N2O3 / 76g N2O3
 Or 76 g N2O3 / 1 mol N2O3

 Known = 7.60 mol N2O3 unknown = mass
 Conversion mole -> mass
 Conversion factor = 76 g N2O3 / 1 mol N2O3
 7.20 mol N2O3 x 76 g N2O3 / 1 mol N2O3
 = 547.2
 = 5.47 x 102 g N2O3
Lets practice more!
 Question 18 a, b, f
 Question 19 a, c, g
The volume of a mole of gas
 Standard Temperature and Pressure (STP) = 0°C and 1 atm

 At STP the volume of 1 mole of any gas is   22.4L
 This can be used as a conversion factor!
Lets practice
 Questions 20-21 p.158
 Question 23 p.159
Gas density
 Density is the amount of mass in a given volume.
 The density of gases is measured in g/L
 The density can be used as a conversion factor to calculate
the molar mass of a gas.
 If you know the mass of 1L, you can calculate the mass of
22.4L easily
Using gas density
Imagine you know that the density of a compound containing
carbon and oxygen is 1.96 g/L at STP. Is the gas CO or CO2?
The volume of both gases at STP is 22.4.
The molar mass must be:
22.4L of gas x 1.96g = 43.9g of unknown gas
1L
The molar mass of CO is 12.0g C +16.0g O = 28.0g
The molar mass of CO2 is 12.0g C + 16.0g O = 44.0g
Therefore the gas must be CO2
Give Question 23 on p.159 a try!
Converting between units using
moles…
Ultimate practice!
 Questions 24-27 p.161
 Question 48-52 p.171

```
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
 views: 4 posted: 9/18/2012 language: simple pages: 14