The Mole Flashcards
Definition of Amount of Substance
The quantity whose unit of the mole, used as a means of counting species such as atoms, ions and molecules
Definition of Mole
The amount of any substance containing as may elementary particles as there are carbon atoms in exactly 12 g of the carbon-12 isotope
6.02 x 10^23
Definition of Avogadro Constant
The number of atoms per mole of the carbon-12 isotope
Equation to find number of particles of substances
Moles= number of atoms/ avogadros constant
Definition of Molar mass
The mass per mole of a substance in units gmol^-1
Equation using mass and moles
Moles= mass in g/ molecular mass
Definition of empirical formula
The simplest whole number ratio of atoms of each element present in a compound
How do you find empirical formula of a compound
- Lay it out in a table and write masses or % mass
- Find the moles of each element in the compound
- Divide by the smallest moles
- Then multiply or something to get all the numbers to be whole numbers
Definition of Molecular Formula
The chemical formula that gives the total number of atoms of each element in each molecule of a substance.
How to find molecular formula
- Find empirical formula
- Work out molecular mass of empirical formula
- Compare to molecular mass given
- See what multiple of it it is. Then multiply the numbers in the formula by this.
Definition of anhydrous
Contains no water molecules
Definition of hydrated
A crystalline compound containing water molecules
Definition of water of crystallisation
Water molecules that are bonded into a crystalline structure of a compound
How to calculate water of crystallisation
- Calculate moles of anhydrous solid left after heating
- Calculate mass of water lost
- Calculate moles of water lost
- Divide moles of water by moles of anhydrous solid
Calculation of percentage error
Percentage error= total uncertainty/value measured * 100
If there are two measurements add the uncertaintities
Definition of solute
The material which dissolves
Definition of solvent
The liquid it dissolves in
Definition of solution
The resulting mixture formed from dissolving a solute in a solvent
Definition of concentration
The amount of solute, in moles, dissolved in 1 dm3 of solution
Equation using concentration
Moles= concentration (moldm-3) x volume (dm3)
How to convert form mol dm-3 to g dm-3
- Do same equation as if you were calculating mol dm-3
2. But multiply the moles by the molecular mass and divide that by the volume.
Molar gas volume equation
Volume= moles x 24
at room temp and pressure
Ideal gas equation
PV=nRT
Units needed in ideal gas exchange equation
Pressure- Pa
Volume- m^3
Temperature- K
Amount- Mole
How to convert the units
1 atm = 1.0 x 10^5 Pa so (1x10^5 * atm) =Pa
1 dm^3 = 0.001 m^3
-273 celsius = 1 K
Why should CO2 not be collected over water
It dissolves in water
