7.3. Preparation of salts
A subsection of Chemistry, 0620, through 7. Acids, bases and salts
Listing 10 of 150 questions
Soluble salts can be made by adding a metal carbonate to a dilute acid. Give the formula of the dilute acid which reacts with a metal carbonate to form a nitrate salt. A student wanted to make hydrated iron(sulfate crystals, FeSO4•xH2O, by adding excess iron(carbonate to dilute sulfuricacid. The student followed the procedure shown. step 1 Add dilute sulfuric acid to a beaker. step 2 Add small amounts of iron(carbonate to the dilute sulfuricacid in the beaker until the iron(carbonate is in excess. step 3 Filter the mixture formed in step2. step 4 Heat the filtrate until it is a saturated solution. Allow to cool. step 5 Once cold, pour away the remaining solution. Dry the crystals between filter papers. Why must the iron(carbonate be added in excess in step 2? State two observations in step2 that would show that iron(carbonate was in excess.  Describe what should be done during step3 to ensure there is a maximum yield of crystals. A saturated solution is formed in step4. Describe what a saturated solution is. Name a different compound that could be used instead of iron(carbonate to produce hydrated iron(sulfate crystals from dilute sulfuricacid. On analysing the crystals, the student found that one mole of the hydrated iron(sulfate crystals, FeSO4•xH2O, had a mass of 278 g. Determine the value of x using the following steps: ● ● calculate the mass of one mole of FeSO4  mass = g ● ● calculate the mass of H2O present in one mole of FeSO4•xH2O  mass of H2O = g ● ● determine the value of x.  x =  Insoluble salts can be made by mixing solutions of two soluble salts. A student followed the procedure shown to make silver bromide, an insoluble salt. step 1 Add aqueous silver nitrate to a beaker. Then add aqueous potassium bromide and stir. step 2 Filter the mixture formed in step1. step 3 Dry the residue. State the term used to describe this method of making salts. Give the observation the student would make during step1. Write the ionic equation for the reaction between aqueous silver nitrate and aqueous potassiumbromide. Include state symbols. Sodiumchloride is an ionic salt. It can be made by reacting sodium with chlorine gas. The equation for this reaction is shown. 2Na+ Cl 2→ 2NaCl Calculate the volume of chlorine gas, in cm3, that reacts to form 2.34 g of NaCl . The reaction takes place at room temperature and pressure.  volume of chlorine gas = cm3 Sodiumchloride does not conduct electricity when solid, but does conduct electricity when molten. Explain why, in terms of structure and bonding. Name the product formed at the positive electrode when electricity is passed through molten sodiumchloride. State the type of change that occurs at the positive electrode in . Explain your answer in terms of electron transfer. type of change explanation  Describe what else can be done to sodiumchloride to allow it to conduct electricity. 
0620_w20_qp_42
THEORY
2020
Paper 4, Variant 2
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Questions Discovered
150