Neutralisation and making saltsIB MYP Chemistry: Mind map

Exam questions on Neutralisation and making salts

1. A school technician in Dubai prepares blue crystals of copper(II) sulfate for a Year 9 class. She warms 50 cm³ of dilute sulfuric acid and adds black copper(II) oxide a spatula at a time, stirring, until some black solid remains at the bottom of the beaker. She then filters the mixture and heats the blue filtrate in an evaporating basin until crystals begin to form at the edge.
   Explain why the mixture must be filtered before the filtrate is heated.2 marks
2. A student in Nairobi investigates how the mass of calcium carbonate affects the volume of carbon dioxide made. Each time, she adds a different mass of calcium carbonate chips to 50 cm³ of 1.0 mol dm⁻³ hydrochloric acid in a flask connected to a gas syringe, and records the total volume of gas collected once the fizzing stops. Masses of 0.5 g, 1.0 g, 1.5 g, 2.0 g, 3.0 g and 4.0 g give volumes of 120 cm³, 240 cm³, 360 cm³, 480 cm³, 600 cm³ and 600 cm³ respectively.
   Describe the trend in the results for masses of calcium carbonate from 0.5 g to 2.0 g.2 marks
3. A student in Singapore wants to find out how much 0.100 mol dm⁻³ hydrochloric acid is needed to neutralise 25.0 cm³ of sodium hydroxide solution. She uses a pipette, a burette, a conical flask and phenolphthalein indicator, which is pink in alkali and colourless in acid. She repeats the titration several times. Her titres are 24.8 cm³, 24.3 cm³, 24.4 cm³ and 24.5 cm³.
   Describe how the student should carry out the first titration, from filling the burette to finding the titre.3 marks