CIE Jun 2017 v3 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. Combustion data cannot distinguish between different structural isomers. (a) Define the term structural isomers.[2] (b) P is a hydrocarbon, CxHy. A gaseous sample of P occupied a volume of 25 cm3 at 37 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 (so that the water produced is liquid and its volume can be ignored), was 150 cm3. Treating the remaining gaseous mixture with concentrated alkali, to absorb carbon dioxide, decreased the volume to 50 cm3. The equation for the complete combustion of P can be represented as shown. CxHy + (x + y 4)O2 xCO2 + y 2H2O (i) Use the data given to calculate the value of x. (ii) Use the data given to calculate the value of (x + y 4). x =[1]UCLES 2017 9701/23/M/J/17 (x + y 4) =[1]<br /> PMT If you were unable to calculate values in (b)(i) and (b)(ii) then use the data in this box for the remaining parts of this question. These are not the correct values. x = 6 (x + y 4) = 9 (iii) Give the molecular formula and the empirical formula of P. molecular formula of Pempirical formula of P[2] (iv) P is unbranched. Give the skeletal formulae for two possible structures of P that are positional isomers of each other. (v) Use the general gas equation to calculate the mass of P present in the original 25 cm3 gaseous sample, which was measured at 37 C and 100 kPa. Give your answer to three significant figures. [2] mass =g [3] [Total: 11]UCLES 2017 9701/23/M/J/17 [Turn over<br />

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