The value of the Avogadro constant is 6.02×10236.02 \times 10^{23}6.02×1023.
What is meant by the Avogadro constant?
Calculate the number of sulfur trioxide molecules in 120 g120\text{ g}120 g of sulfur trioxide, SO3\text{SO}_3SO3. (Relative atomic masses: S=32.0\text{S} = 32.0S=32.0, O=16.0\text{O} = 16.0O=16.0)
Give your answer to 3 significant figures.
A student is reacting lithium oxide with hydrochloric acid.
Look at the equation for the reaction.
Li2O+2HCl⟶2LiCl+H2O \text{Li}_2\text{O} + 2\text{HCl} \longrightarrow 2\text{LiCl} + \text{H}_2\text{O} Li2O+2HCl⟶2LiCl+H2OThe student wants to make 34.0 g34.0\text{ g}34.0 g of lithium chloride, LiCl\text{LiCl}LiCl.
Calculate the masses of lithium oxide and hydrochloric acid that they need. (Relative atomic masses: Li=7.0\text{Li} = 7.0Li=7.0, O=16.0\text{O} = 16.0O=16.0, H=1.0\text{H} = 1.0H=1.0, Cl=35.5\text{Cl} = 35.5Cl=35.5)
91 exam-style questions on OCR GCSE Chemistry Monitoring chemical reactions. Each one has a worked solution and a mark scheme showing where the marks go.