Unit 5 Part 7 Moles Grams And LitersPresentation Transcript
Part 7 – Moles into Grams and Liters
WEIGHING (MASSING) IN CHEMISTRY
Chemists use mass, and normally small masses such as grams.
However they must relate the mass of chemical back to the counting of individual atoms.
The Gram Atomic Mass (GAM)
gram atomic mass- the mass of one mole of an element.
The gram atomic mass numerically equals the atomic mass of the element in grams.
Find the gram atomic mass of the following elements:
Na, Hg, Fe, S
Gram Formula Mass (GFM)
gram formula mass- the mass of one mole of a compound.
For gram formula mass we add together the gram atomic masses of the elements which make up the compound.
Find the gram formula mass of the following compounds:
CoCl 2 , H 2 O, H 2 S0 4
Name these compounds.
Converting between moles and grams of a substance.
Conversions between moles and the mass of a substance uses the gram atomic mass or gram formula mass.
To convert from moles to grams
1. Find the gram formula mass of the compound or element your looking for.
2. Determine the number of moles you were given.
3. Multiply the number of moles by the gram formula mass.
Find the mass of 0.160 mol H 2 O 2 .
Find the mass of 6.0 X 10 26 atoms of Be.
To convert from grams to moles
1. Find the gram formula mass of the compound you are looking for.
2. Determine the number of grams you were given.
3. Divide the number of grams you were given by the gram formula mass.
Find the number of moles in each of the following:
333g SnF 2 .
5.0 X 10 24 molecules of SnF 2 .
Try these on you own...
Find the mass in each of the quantities below
10.0 mol Cr
3.32 mol K
2.4 mol N 2
Find the number of moles in each of the quantities below
10g H 2 O 2
15g Ca(NO 3 ) 2
50g C 20 H 42
FINDING VOLUME IN CHEMISTRY
The Volume of a mole of gas
Although the volumes of 1 mol of a liquid or solid can vary greatly between different substances, the volume of 1 mol of the gas of any substance has the same volume, at equal temperature and pressure.
1 mole of a gas of any substance occupies a volume of 22.4L at STP (standard temperature and pressure).
Standard Temperature and Pressure (STP)
Temperature and pressure can affect the volume of a gas.
In order to “standardize” experiments between scientist, we use a standard set of values to work with gases.
Standard Temperature = 0°C
Standard Pressure = 1 atm (air pressure at sea level)
Determine the volume, in liters, of 0.600 mol of SO 2 gas at STP.
What is the volume at STP of 0.960 mol CH4?
Assuming STP, how many moles are in 89.6 L SO 2 ?
Converting between units with moles
The mole is the most useful way for chemists to express the amount of matter.
Determine the volume in liters of 50g of SO 2 gas at STP.