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Amount of substance

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Question 1

Compound C\mathbf{C}C is a hydrated ionic compound with the empirical formula: MgH12N2O12\text{MgH}_{12}\text{N}_2\text{O}_{12}MgH12​N2​O12​.

A student investigates the thermal decomposition of compound C\mathbf{C}C as outlined below.

Stage 1

The student gently heats 0.00500 mol0.00500\text{ mol}0.00500 mol of compound C\mathbf{C}C to remove the water of crystallisation. 0.540 g0.540\text{ g}0.540 g of water is collected, leaving 0.00500 mol0.00500\text{ mol}0.00500 mol of the anhydrous compound D\mathbf{D}D.

Stage 2

The student strongly heats 0.00500 mol0.00500\text{ mol}0.00500 mol of compound D\mathbf{D}D, which decomposes to form a solid oxide E\mathbf{E}E (molar mass of 40.3 g mol−140.3\text{ g mol}^{-1}40.3 g mol−1) and 300 cm3300\text{ cm}^3300 cm3 of a gas mixture, measured at RTP, containing gases F\mathbf{F}F and G\mathbf{G}G.

Stage 3

The student cools the 300 cm3300\text{ cm}^3300 cm3 gas mixture of F\mathbf{F}F and G\mathbf{G}G.

  • Gas F\mathbf{F}F is a compound that condenses to form 0.460 g0.460\text{ g}0.460 g of a liquid.
  • Gas G\mathbf{G}G remains and has a volume of 60 cm360\text{ cm}^360 cm3, measured at RTP. Gas G\mathbf{G}G is tested and it relights a glowing splint.

Determine the formulae of C\mathbf{C}C, D\mathbf{D}D, E\mathbf{E}E, F\mathbf{F}F and G\mathbf{G}G.

Show all your working and equations for the reactions.

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Amount of substance Questions

  1. A Level
  2. /Chemistry
  3. /Amount of substance