IB chemistry topic 1
Terms in this set (44)
Chemical combination of different elements with fixed ratios of atoms
Describes a substance e.g. NaCl
Burning in air
Composed of 2+ substances which are not chemically bonded to each other. They have no fixed ratio or formula
A mixture in which the composition is uniform throughout
A mixture in which the composition is not uniform throughout
-Least distance between particles
-Strong inter-particle forces
-Vibrate around position
-Fixed shape and volume
-More distance between particles
-Weaker inter-particle forces
-Slide over each other
-Not fixed shape
-Largest distance between particles
-No inter-particle forces
-No fixed shape or volume
Liquids and gases, they can flow and have no fixed shape
Gas to solid
Solid to gas
Liquid to solid
Solid to liquid
Gas to liquid
Liquid to gas
Evaporation: only on surface below boiling point
Boiling: Throughout at boiling point
A temperature at which vapour pressure reaches external pressure.
Avagadro's number =
6.02 x 10^23
-SI base unit
-For amount of substance
Equation for number of moles =
n=number of moles
m=mass in grams
Relative formula mass
Mr = Sum of weighted averages of the mass of all atoms in a formula
is the Mr or Ar in grams
the simplest whole number ratio of atoms in a molecule or formula unit
the actual ratio number of atoms in a molecule
The empirical formula is found by ...
1. Find the amount of substance
2. Change to moles
3. Divide by smallest number of moles
4. Multiple (if required) to a whole number ratio
Water of crystillisation
-Water molecules included in crystal lattice
-Water can be forced out by heat
Finding the molecular formula
Steps for the combustion analysis of an organic compound
Sample burnt in O2, products analysed
1. Find mass of atoms other than O
2. Subtract from the total mass of products to find the mass of combined O.
3. Convert C, H and O to moles
4.Divide by smallest number of moles
5. Multiple (if required) to a whole number ratio
The reactant that is used up first and causes the reaction to end. It determines the quantity of product formed.
Reactant(s) that is (are) not fully used up
The quantity of product that could form if a complete conversion of the limiting reactant was achieved.
Actual amount of product in an experiment. Usually less than the theoretical yield due to side reactions and incomplete conversion.
actual yield / theoretical yield x 100
Equal volumes of gases at the same temperature and pressure contain equal numbers of particles
standard temperature and pressure
the volume occupied by 1 mole of a gas at standard temperature and pressure (STP); 22.7 dm3
The number of moles of a gas at STP
Which temperature scale should be used for gas calculations
Ideal gas law assumptions
-Particles have no volume (they are negligible compared to container)
-No forces act between particles
-Particles are point masses
-Gas obeys the ideal gas law
Ideal Gas Law =
PV = nRT
If temp is constant, increasing the pressure on a fixed amount of gas decreases it's volume.
If the pressure is constant then increasing the temp on a fixed amount of gas increase it's volume.
If volume is held constant then increasing the temp of a fixed amount of gas will increase it's pressure.
3 gas laws combined =
see image ...