| How is a solution formed? | when a solute dissolves in a solvent |
| What's the formula for concentration | concentration (g/dm^3) = mass of solute (g) ÷ volume (dm^3) |
| How can concentration be increased? | 1) by dissolving more solute in a given volume of solution - this increases the mass of the solute
2) by allowing some of the solvent to evaporate - this decreases the volume of the solution |
| What's the equation linking No. of Particles, Avogadro's constant & amount(mol)? | No. of particles = Avogadro's constant × amount of substance in mol |
| What's the equation linking Mass, Rfm & amount(mol)? | Mass = relative formula mass × amount |
| In a balanced equation, what shows the amount(mol) of products and reactants? | The coeficient (number infront of formulae). No coefficient means 1 mol |
| What is a limiting reactant? | The reactant that is all used up. This is what The mass of product formed in a reaction depends on |
| What's the excess? | the reactant that is left over |
| 12 g of magnesium reacts completely with excess hydrochloric acid to form magnesium chloride and hydrogen:
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
Calculate the maximum mass of hydrogen that can be produced. (Ar of Mg = 24, Mr of H2 = 2) | Amount of magnesium = mass ÷ rfm
Amount of magnesium = 12/24
= 0.5 mol
Looking at the equation, 1 mol of Mg forms 1 mol of H2, so 0.5 mol of Mg forms 0.5 mol of H2
Mass of H2 = Mr × amount
= 2 × 0.5
= 1 g |
| What's the equation for concentration? | Concentration(mol/dm^3) = amount of solute(mol) ÷ volume (dm^3)
REMEMBER: × by 100 to go from dm^3 to cm3 |
| How do you convert between mol/dm^3 to g/dm^3 (vice versa)? | '×' by the rfm (to go from g/dm^3 to mol/dm^3 '÷' by the rfm) |
