1. 1
   A student dissolves 4.0 g of sodium hydroxide (Mr = 40) in water and makes the volume up to 250 cm3 of solution in a volumetric flask.

   (a)

   Which equation should the student use to calculate the concentration of the solution, in mol/dm3?

   [1 mark]

   • AConcentration = number of moles / volume of solution (dm3)
   • BConcentration = volume of solution (dm3) / number of moles
   • CConcentration = number of moles x volume of solution (dm3)
   • DConcentration = mass of solute / volume of solution (cm3)

   (b)

   What is 250 cm3 expressed in dm3?

   [1 mark]

   • A0.25 dm3
   • B2.5 dm3
   • C25 dm3
   • D250 dm3

   (c)

   Calculate the concentration, in mol/dm3, of the sodium hydroxide solution the student has made, showing your working.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A lab technician makes 2 dm3 of hydrochloric acid solution containing 0.5 mol of dissolved hydrogen chloride.

   (a)

   Which rearrangement of the concentration equation should be used to calculate the concentration of this solution?

   [1 mark]

   • AConcentration = number of moles / volume of solution (dm3)
   • BNumber of moles = concentration / volume of solution (dm3)
   • CVolume of solution (dm3) = concentration / number of moles
   • DConcentration = volume of solution (dm3) x number of moles

   (b)

   What are the standard units used for concentration when calculated using this equation?

   [1 mark]

   • Amol/dm3
   • Bg/dm3
   • Cmol/g
   • Ddm3/mol

   (c)

   Calculate the concentration, in mol/dm3, of the hydrochloric acid solution the technician has made, showing your working.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student is given 500 cm3 of sulfuric acid solution with a concentration of 2.0 mol/dm3 (Mr of sulfuric acid, H2SO4, = 98) and needs to find out how much sulfuric acid, by mass, this sample contains.

   (a)

   Calculate the number of moles of sulfuric acid present in this volume of solution, showing your working.

   [3 marks]

   (b)

   Using your answer to part (a), calculate the mass of sulfuric acid, H2SO4 (Mr = 98), present in the 500 cm3 sample, showing your working.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Two laboratory teams each need to prepare a solution of a precise concentration. A hospital pharmacist needs to prepare 1.5 dm3 of saline solution with a concentration of 0.15 mol/dm3 of sodium chloride (Mr = 58.5). An electroplating laboratory needs to prepare 750 cm3 of copper sulfate solution with a concentration of 0.4 mol/dm3 (Mr = 160).

   (a)

   A hospital pharmacist needs to prepare 1.5 dm3 of saline solution with a concentration of 0.15 mol/dm3 of sodium chloride (Mr = 58.5). Calculate the mass of sodium chloride the pharmacist must dissolve to prepare this solution, showing full working.

   [6 marks]

   (b)

   The electroplating laboratory needs to prepare 750 cm3 of copper sulfate solution with a concentration of 0.4 mol/dm3 (Mr = 160). Calculate the mass of copper sulfate the laboratory must dissolve to prepare this solution, showing full working.

   [6 marks]

   Total for question 4: 12 marks

End of questions