Chemistry · May / June 2022 · Paper 42 · Question 2
0620
As printed in the paper
The question as text
Calcium hydroxide, Ca(OH)2, is slightly soluble in water.
Read automatically from the paper; the printed page above is exact.
Show the answer and mark scheme
2(a)(i)[2]
Ca + 2H2O → Ca(OH)2 + H2
M1 H2 as product
M2 Fully correct equation
2(a)(ii)[1]
7 < pH ⩽ 12
calcium oxide
2(b)(i)[1]
The answer is a drawing: see the picture of this mark scheme row.
2(b)(ii)[1]
OH–
2(c)(i)[1]
carbon dioxide
2(c)(ii)[2]
(a solution that) can dissolve no more solute
at a given temperature
2(c)(iii)[2]
add excess (solid) calcium hydroxide (to water)
filter
2(c)(iv)[3]
(aqueous) sodium hydroxide
white ppt
insoluble / remains in excess
2(d)(i)[1]
burette
2(d)(ii)[1]
neutralisation
2(d)(iii)[1]
indicator
2(d)(iv)[5]
M1 Mol HCl = 0.0500 × 20.0 / 1000 = 0.001(00)
M2 Mol Ca(OH)2 = M1 / 2 = 0.00100 / 2 = 0.0005(00)
M3 M2 × 1000 / 25 = 0.0005(00) × 40 = 0.02(00)
M4 Mr Ca(OH)2 = 74
M5 M4 × M3 = 74 × 0.02 = 1.48 (g / dm3)
Make a free account to save your answers and see your weak topics and ask the AI why a wrong answer is wrong.