Unit 3: Quantitative Chemistry

Relative Formula Mass
1. The relative mass is just the relative atomic masses of all of the elements in the molecular formula added together.
2. Percentage of mass of an element in a compound =
  1. Ar x number of atoms of that element ____________________________________________________ x 100 Mr of the compound
The Mole and Mass
1. One mole of any substance is just the amount of the substance that contains an Avogadro number of particles.
  1. This means that there are the same number and same type of atoms on each side of the reaction equation.
  2. Because of this, no mass is lost or gained, we say the mass is conserved during a reaction.
  3. E,g. 2LI + F2 = 2LiF
2. Avogadro Constant = 6.02 x 10↑23
3. E,g. Carbon has an A of 12g. So one mole of carbon weighs exactly 12g.
4. Number of Moles =
  1. mass in g (of an element or compound ---------------------------------------------------------------------------- Mr (of the element or compound
5. In a chemical reaction, mass is always conserved.
6. During a chemical reaction, no atoms are destroyed and no atoms are created.
7. if a mass seems to change, there's normally a gas involved..
The Mole and Equations
1. The numbers in chemical equations mean different things.
2. You can balance equations using reacting masses.
3. Reactions stop when one reactant is used up.
4. Volume of gas =
  1. Mass of gas ------------------ Mr of gas

Resource summary

	Created by Callum Ellwood over 6 years ago