1.2 Amounts Of Substance (part 1) Flashcards
Relative atomic mass
Weighted average mass of all the isotopes relative to 1/12th mass of an atom of carbon-12
Relative molecular mass
Mass of a molecule of the compound relative to 1/12th of the mass of an atom of carbon-12
Relative formula mass
Mass of one formula unit of an ionic compound relative to 1/12th mass of an atom of carbon-12
Mole
Amount of substance that contains as many particles as there are in exactly 12g of carbon-12
Avogadros constant
- 02x10 (to the power) 23
or. There are 6.02x10 (to the power) 23 atoms of carbon in 12g carbon-12
Does a mole of one substance contain the same number of particles as a mole of any other substance
Yes
What do you need to know to calculate moles in a solid
Mass
What do you need to calculate the number of moles in a gas
Volume
What do you need to know to calculate the number of moles in a solution
Volume and concentration
How do you get from Mg to mg
/1000
How to you get from mg to g
/1000
How do you get from Mg to g
/1000000
How to get from g to kg
/1000
How to get from kg to tonnes
/1000
How to get from g to tonnes
/1000000
How to get from tonnes to kg
X1000
How to get from kg to g
X1000
How to get from tonnes to g
X1000000
How to get from g to mg
X1000
How to get from mg to Mg
X1000
How to get from g to Mg
X1000000
Formula for calculating moles in solids
Mass (in g) = moles x Mr
How to calculate the number of atoms in a gives mass
First calculate number of moles using mass/Mr
Then calculate number of atoms using moles x avogadros constant
How to get from centimetres cubed to decimetres cubed
/1000
How to get from decimetres cubed to centimetres cubed
X 1000
What do you need to know in order to calculate the number of moles in a solution
Volume in demimetres cubed
Concentration in moles per decimetres cubed
What is concentration
The number of moles of a solute dissolved in one decimetre cubed of solution
What is the formula to work out the number of moles in a solution
Moles = volume x concentration
How to calculate the concentration of a solution given the mass and volume
Moles= mass/Mr Concentration= moles/volume in decimetres cubed
What are the assumptions made when using the ideal gas equation to
- there are no intermolecular forces between the molecules
* the volume occupied by the molecules is entirely negligible relative to the volume of the container
What is the ideal gas equation
pV = nRT
What unit is the answer always given in
Metres cubed
What is pressure measured in
Pascals, Pa
How to get from kPa to Pa
X 1000
How to get from MPa to Pa
X1000000
What is volume measured in
Metres cubed
How to get from centimetres cubed to metres cubed
/1000000
How to get from decimetres cubed to metres cubed
/1000
What is n
Number of moles
What is R
Gas constant: 8.314
What is T measured in
Kelvin, K
How to get from Celsius to kelvin
+ 273
How to get from kelvin to Celsius
-273
What is density
It’s mass per unit volume
Formula for density
Mass = density x volume
What is density usually measured in
Grams per centimetre cubed
Empirical formula
Simplest whole number ratio of atoms of each element present in a molecule
Molecular formula
Actual number of atoms of each element present in a molecule
How to calculate molecular formula
Calculate empirical formula
Calculate relative mass of empirical formula
Use Mr to calculate how many times bigger molecular formula needs to be compared to empirical
Times number of atoms by how many times bigger mr is than empirical formula mass