Quelpr
1 markMole Concept

CSEC Chemistry · January 2017 · Paper 2 · Question 1(d)(iv)

Calculate the number of moles of KMnO4 in the average volume determined in (c)(iii).

The mark scheme is shown once you've answered.

Practise this question

Other parts of this question

  1. 1(a)Define the term 'standard solution'.[1 mark]
  2. 1(b)Complete Table 1 by calculating the mass of the hydrated iron(II) sulfate used.[1 mark]
  3. 1(c)(i)Record the final burette volumes from the diagrams in Figure 1 in the appropriate spaces in Table 2.[3 marks]
  4. 1(c)(ii)Calculate the volume of KMnO4 solution used in EACH titration and enter them in Table 2.[3 marks]
  5. 1(c)(iii)Determine the average volume of KMnO4 solution used in the titrations.[1 mark]
  6. 1(d)(i)As shown in the equation, 1 mole MnO4⁻ reacts with 5 moles of Fe²⁺. Using the result in (c)(iv), calculate the number of moles of Fe²⁺ ions in the 25.0 cm³…[1 mark]
  7. 1(d)(ii)Determine the number of moles of Fe²⁺ in the 250.0 cm³ volumetric flask.[1 mark]
  8. 1(e)Given that 1 mole of FeSO4 contains 1 mole of Fe²⁺ ions, use the result from (d)(ii) to calculate the mass of anhydrous FeSO4 in the 250 cm³ volumetric flask.…[1 mark]
  9. 1(f)Calculate the mass of water in the hydrated FeSO4 using the following formula: Mass of water = mass of hydrated FeSO4 [from (b)] - mass of anhydrous FeSO4…[1 mark]
  10. 1(g)Calculate the number of moles of water in the hydrated sample. [The relative molecular mass of water is 18.0.][1 mark]
  11. 1(h)Using the results from (d)(ii) and (g), calculate the value of n in the formula FeSO4•nH₂O. n = number of moles of water in hydrated sample / number of moles…[1 mark]
  12. 1(i)What is the colour change at the endpoint of the titration of iron(II) sulfate with potassium manganate(VII)?[2 marks]
  13. 1(j)State ONE reason why there was no need to add an indicator to this titration.[1 mark]
  14. 1(k)(i)Aqueous sodium hydroxide was added dropwise, and then in excess. Inference: Fe²⁺ ions present.[2 marks]
  15. 1(k)(ii)The resulting mixture from (i) was left to stand in air. Inference: Fe²⁺ ions oxidized to Fe³⁺.[2 marks]
  16. 1(k)(iii)Aqueous barium nitrate was added, followed by dilute nitric acid. Inference: SO4²⁻ ions present.[2 marks]

More practice: the rest of this paper · more Mole Concept questions · all CSEC Chemistry past papers