Combustion data can be used to calculate the empirical formula, molecular formula and relative molecular mass of many organic compounds.

1. (a)Define the term relative molecular mass.[2]
2. (b)(i)T is an alcohol, CₓHᵧO. A gaseous sample of T occupied a volume of 20 cm³ at 120°C and 100 kPa. The sample was completely burned in 200 cm³ of oxygen (an excess). The final volume, measured under the same conditions as the gaseous sample, was 250 cm³. Under these conditions, all water present is vaporised. Removal of the water vapour from the gaseous mixture decreased the volume to 170 cm³. Treating the remaining gaseous mixture with concentrated alkali, to absorb carbon dioxide, decreased the volume to 110 cm³. The equation for the complete combustion of T can be represented as shown. CₓHᵧO + zO₂ → xCO₂ + (y/2)H₂O Use the data given to calculate the value of x.[1]
3. (b)(ii)Use the data given to calculate the value of y.[1]
4. (b)(iii)If you were unable to calculate values for x and y then use x = 4 and y = 10 for the remaining parts of this question. These are not the correct values. Complete the equation for the complete combustion of the alcohol, T. ................. + .........O₂ → ................CO₂ + ................H₂O[1]
5. (b)(iv)Give the skeletal formulae for two possible structures of T. Name each alcohol.[2]
6. (b)(v)Use the general gas equation to calculate the mass of T present in the original 20 cm³ gaseous sample, which was measured at 120°C and 100kPa. Give your answer to three significant figures. Show your working.[3]