A solution of potassium iodide, KI\text{KI}KI, is mixed with a solution of lead nitrate, Pb(NO3)2\text{Pb(NO}_3\text{)}_2Pb(NO3)2. Lead iodide, PbI2\text{PbI}_2PbI2, and potassium nitrate, KNO3\text{KNO}_3KNO3, are formed.
Write the two missing balancing numbers in the spaces.
_ KI+Pb(NO3)2→PbI2+_ KNO3\_\;\text{KI} + \text{Pb(NO}_3\text{)}_2 \rightarrow \text{PbI}_2 + \_\;\text{KNO}_3_KI+Pb(NO3)2→PbI2+_KNO3
A different reaction is carried out in an open flask on a balance. A gas is produced and the balance reading decreases.
Explain why the balance reading decreases.
95 exam-style questions on AQA GCSE Chemistry 3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, covering 3.1.1 Conservation of mass and balanced chemical equations, 3.1.2 Relative formula mass, 3.1.3 Mass changes when a reactant or product is a gas, and 3.1.4 Chemical measurements. Each one has a worked solution and a mark scheme showing where the marks go.