A student is making a sample of the insoluble salt barium sulfate, BaSO4. To do this, the student mixes aqueous sodium sulfate, Na2SO4(aq), with aqueous barium chloride, BaCl2(aq).
The student then follows these stages.
step 1 Put 0.100 moles of solid BaCl2 into 100 cm3 of distilled water in a beaker so that BaCl2(aq) is formed.
step 2 Pour an aqueous solution containing 0.100 moles of Na2SO4(aq) into the beaker with the BaCl2(aq) made in step 1.
step 3 Stir the mixture, then filter it.
step 4 Leave the solid that remains on the filter paper to dry.
(a)[2]
Complete the symbol equation for this reaction and include state symbols. BaCl2(aq) + Na2SO4(aq) → BaSO4(.....) + .................(.....)
(b)[2]
Calculate the mass of solid BaCl2 dissolved in step 1.
(c)[1]
Calculate the volume, in cm3, of 1.25 mol/dm3 Na2SO4(aq) added in step 2 that contains 0.100 moles of Na2SO4.
(d)[1]
State the colour of the solid produced in step 2.
(e)[1]
State the general term used for a solid left on the filter paper after filtration.
(f)[2]
Suggest what the student should do in this extra step, and explain why the measured mass collected is greater than the predicted mass.
(g)[1]
State the name of this method of salt preparation.
(h)[3]
State the requested names.
Worked solution & mark scheme
This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: “The balanced equation is → BaSO4(s) + 2NaCl(aq)” …