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2 marksThe Mole Concept

CAPE Chemistry Unit 1 · 2007 · Paper 2 · Question 1(b)(i)

20 cm³ of a solution of phosphorous (V) acid containing 1.96 g dm⁻³ reacted with 25 cm³ of a solution containing 1.28 g dm⁻³ sodium hydroxide to give a solution of sodium hydrogen phosphate (Na₂HPO₄). Relative atomic masses: P = 31.0, H = 1.0, Na = 23.0, O = 16.0.

Calculate the number of moles of phosphorous (V) acid that reacted.

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Other parts of this question

  1. 1(a)(i)Define the term mole.[2 marks]
  2. 1(a)(ii)Define the term molar mass.[1 mark]
  3. 1(a)(iii)State the units of molar mass.[1 mark]
  4. 1(b)(ii)Calculate the number of moles of sodium hydroxide that reacted.[1 mark]
  5. 1(b)(iii)Calculate the number of moles of sodium hydroxide that reacted with 1 mole of the acid.[1 mark]
  6. 1(c)Derive the equation for the reaction that occurred in Part (b) above.[1 mark]
  7. 1(d)(i)State Avogadro's Law.[1 mark]
  8. 1(e)Outline the experimental steps involved in carrying out the reaction described in (b) on page 2.[5 marks]

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