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A-LEVEL CHEMISTRY PRACTICE P 3 1 A 5.00 g sample of potassium chloride was added to 50.0 g of water initially at 20.0 °C. The mixture was stirred and as the potassium chloride dissolved, the temperature of the solution decreased. (a)Describe the steps you would take to determine an accurate minimum temperature that is not influenced by heat from the surroundings. (b)The temperature of the water decreased to 14.6 °C. Calculate a value, in kJ mol−1, for the enthalpy of solution of potassi...

1 The following table gives the names and structures of some structural isomers with the molecular formula C5H10 (a)Isomer 1 exists as E and Z stereoisomers. (i)State the meaning of the term stereoisomers (ii)Draw the structure of the E stereoisomer of Isomer 1.

1 In this question, give all values of pH to 2 decimal places. (a)The ionic product of water has the symbol Kw (i)Write an expression for the ionic product of water. __________________________________________________________ (1) (ii)At 42°C, the value of Kw is 3.46 × 10−14 mol2 dm−6. Calculate the pH of pure water at this temperature (to 2 decimal places). __________________________________________________________ (iii)At 75 °C, a 0.0470 mol dm–3 solution of sodium hydroxide h...

1 AqA EXAMPRO A-LEVEL CHEMISTRY Practice Paper 1 MARK SCHEME Maximum marks: 105 View detailed guidance on the conclusions you can draw from your students' performance in these papers on the MERiT welcome page. Understand how your students compare with others and target revision effectively by entering marks into MERiT. (a) (i) [H+][OH-J OR (H3O+][OH-J Ignore (aq) Must have [ J not () (ii) 3.46 X 10-14 (= 1.86 X 10-7) If no square root, CE= 0 pH= 6.73 Must be 2dp (iii) [H+] = 10...

Q1. (a) (i)M1 (Compounds / molecules with) the same structural formula2 Penalise M1 if ‘same structure’ or ‘different structural / displayed formula’. M2 with atoms / bonds / groups arranged differently in space OR atoms / bonds / groups with different spatial arrangements / different orientation Ignore references to ‘same molecular formula’ or ‘same empirical formula’. Mark independently. (b)M1 Br2 OR bromine (water) OR bromine (in CCl4 / organic solvent)1 If M1, has no r...

A-LEVEL CHEMISTRY MARK SCHEME Practice Paper 3 1.(a)Start a clock when KCl is added to water 1 Record the temperature every subsequent minute for about 5 minutes 1 Allow record the temperature at regular time intervals until some time after all the solid has dissolved for M2 Plot a graph of temperature vs time 1 Extrapolate back to time of mixing = 0 and determine the temperature 1 Drawing of suitable graph could score M2, 3 and 4 (b)Heat taken in = m × c × ΔT = 50 × 4.18 × 5.4 = 1...