CIE Jun 2017 v1 Paper 2 Q1

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Answer all the questions in the spaces provided. PMT Combustion data can be used to calculate the empirical formula, molecular formula and relative molecular mass of many organic compounds. (a) Define the term relative molecular mass.[2] (b) T is an alcohol, CxHyO. 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. CxHyO + zO2 xCO2 + y 2H2O (i) Use the data given to calculate the value of x. (ii) Use the data given to calculate the value of y. x =[1] y =[1]UCLES 2017 9701/21/M/J/17<br /> PMT 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. (iii) Complete the equation for the complete combustion of the alcohol, T.+ O2 CO2 + H2O (iv) Give the skeletal formulae for two possible structures of T. Name each alcohol.[1] [2] (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 100 kPa. Give your answer to three significant figures. Show your working. mass =g [3] [Total: 10]UCLES 2017 9701/21/M/J/17 [Turn over<br />

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