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4 marksGravimetric Methods of Analysis

CAPE Chemistry Unit 2 · 2014 · Paper 2 · Question 2(e)

Washing soda is hydrated sodium sulfate, Na2SO4.xH2O. A sample is heated in a crucible to constant mass: Mass of crucible = 34.25 g Mass of crucible and washing soda = 40.69 g Mass of crucible and washing soda after heating = 37.09 g (RAM: Na = 23; S = 32; O = 16; H = 1)

Calculate the value of x in the formula Na2SO4.xH2O.

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Other parts of this question

  1. 2(a)(i)Use an arrow to indicate, below the sketch, the direction of increasing frequency.[1 mark]
  2. 2(a)(ii)Identify the region (A, B or C) where EACH of Infrared and X-rays may be found.[2 marks]
  3. 2(b)Calculate the wavelength of electromagnetic radiation with frequency of 4.5 x 10^15 Hz. (Velocity of light = 3.0 x 10^8 m s^-1)[2 marks]
  4. 2(c)State ONE example of the use of gravimetric analysis in quality control.[1 mark]
  5. 2(d)(i)State the purpose for performing Step 1 and Step 4.[2 marks]
  6. 2(d)(ii)State TWO pieces of apparatus that should be used in Step 2.[2 marks]
  7. 2(d)(iii)State the apparatus that should be used in Step 3.[1 mark]

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