(c);;;;;;The mass spectrum of an elements enables the relative abundance ofeach isotope of the element to be determined. Data relating to mass spectrum of an element X whose atomic number is 35 appear as indicated in the table below. Study the data and answer the question that follows:
Mass number of isotopes
;(i);;;;;;;;Define the term isotope
(ii);;;;;;;Write the convention symbols for the two isotopes of element X.
(iii);;;;;Calculate the relative atomic mass of X to three significant figures.
(b) (i) Study the following compounds: hydrogen sulphide (H2S), ammonia (NH3), hydrogen fluoride (HF), chloroform (CHC13) and ethanoic acid (CH3COOH). With reasons, briefly describe the compounds which contain and those which do not contain hydrogen bond.
(ii) Briefly explain why dimethyl ether is more volatile than ethanol although their molecular weights are the same.
(b);;;;;From ideal gas equation, derive the relationship between density of a gas in grams per dm;3, the gas pressure in atmospheres, the temperature (T) in kelvin, the relative molecular mass of a gas (Mr) and the gas constant R.
(b);;;;;When 15g of glucose (C6H1206) was dissolved in 50g of a certain solvent with a relative molecular mass of 180g, the freezing point was depressed by 8.0;0;C. Using these data, calculate the freezing point depression constants, for the solvent.
(c);;;;;Benzene (C6H6) and toluene (C6H5CH3) form an ideal solution. At 333K, the vapour pressure of pure benzene is 53.3kPa while that of pure toluene is 26.7kPa. If a solution is prepared by mixing two moles benzene and three moles of toluene;
(i);;;;;;Find the partial pressure of each component in the vapour phase in equilibrium with this solution at 333.
(ii);;;Calculate the total vapour pressure of the solution.
(iii);Explain which substance will be collected from the top of the distillation column, if a mixture of benzene and toluene is distilled.
(b);;;;;;A solution was prepared by dissolving 2.40g of biphenyl (C12H10) in 75.00g of benzene. Calculate the boiling point of the solution given that Kb = 2.53;0C/m; Kf =5.12;OC/m; boiling point of pure benzene = 80.1oc and freezing point of pure benzene is 5.50C.
(b);;;;;;1.5g of ammonium nitrate (NH N03) was added to 35.0g of water in a plastic beaker and stirred until the salt dissolved. The temperature of the solution dropped from 22.70C to 19.40C. Basing on the given information respond to the following equations:
(i);;;;;;Is the process endothermic or exothermic? Explain.
(ii);;;Calculate the heat of solution of NH4N03 in kJ/moI., given that specific heat capacity of water = 4.184J/g0C
(b);;;;;;10cm3;of a gaseous hydrocarbon Q required 45cm3;of oxygen for complete combustion. Q reacts with I mole of bromine gas to form a brominated compound of relative molecular mass of 200.02 which contains 79.2% bromine.
(i);;;;;;;;Determine the molecular formula of Q. (ii) Give the structural formula of Q.