Mass Calculations

Mole formula

Number of moles = mass/molar mass

Molar mass

Relative molecular mass

Concentration formula

Concentration = mass / volume

Empirical formula

The smallest whole number ratio of atoms of each element in a compound

Molecular formula

Actual numbers of atoms of each type of element in a molecule

Ionic equation

Only shows the reacting particles

Give the ionic equation for the reaction between nitric acid and sodium hydroxide

H⁺ + OH^- → H₂O

How to find the ionic equation

Split all compounds into their ions if they break down into this form, then don’t include ions appearing on both sides

Displacement reaction

A more reactive element takes the place of a less reactive element in a compound

Precipitation reaction

Two aqueous compounds react together to produce a solid product

Gas Law

At the same pressure and temperature, one mole of any gas has the same volume

Molar gas volume

The space that one mole of gas occupies at a certain temperature and pressure

Molar volume equation

Molar volume = volume / molar gas volume

Experiment to measure the molar volume of carbon dioxide at RTP

1- Measure out a set volume of HCl into a conical flask connected to a gas syringe

2- Add a known mass of NaCO₃ to the conical flask replace the bung and allow the reaction to go to completion

3- Record the volume of carbon diode gas collected in the gas syringe

4- Repeat the experiment, varying the mass of NaCO₃ each time

5- Use your results to draw a graph of volume against mass

6- Use the mass and volume from any point to work out molar volume

Ideal Gas equation

Pressure x volume = moles x gas constant x temperature

What is each unit of the ideal gas equation in? (excluding gas constant and moles)

Pressure- Pa

Volume- m³

Temperature- K

Experiment to find the molar mass of an unknown, volatile liquid

1- Place a known mass of the liquid into a flask, then attach it to a sealed gas syringe

2- Warm the flask until the liquid completely evaporates

3- Record the volume of gas in the syringe and temperature of the water bath

4- Use the ideal gas equation to work out how many moles of the liquid were in your sample, then use this for the molar mass