2018 Paper 4 QP with Data

2018 A level H2 Chem Paper 4 QP

Expt VFA1 / cm3 Vwater / cm3 t / s 1/t / s−1 lg(1/t) lg(VFA1) 1 25.00 0.0 27.9 0.0358 −1.45 1.40 2 22.50 2.5 30.2 0.0331 −1.48 1.35 3 20.00 5.0 34.0 0.0294 −1.53 1.30 4 17.50 7.5 38.9 0.0257 −1.59 1.24 5 15.00 10.0 45.7 0.0219 −1.66 1.18 Note: Measuring cylinder is used for distilled water hence precision is up to 0.5cm3.

White ppt, soluble in excess NaOH(aq) to give a colourless solution White ppt, soluble in excess NH3 (aq) to give a colourless solution White ppt CuI dissolves in NH3(aq) to give a colourless filtrate that turns dark blue rapidly. When H2SO4(aq) is added dropwise, pale blue ppt is formed. When more H2SO4(aq) is added, the pale blue ppt turns into a brown suspension. Upon leaving to stand, we can observe white ppt in the brown solution.