pH and indicators
4 marks · NormalA teacher gives three solutions: X with pH 3, Y with pH 7, and Z with pH 12.
Classify each solution as acidic, neutral, or alkaline.
State which solution is strongly acidic and which is strongly alkaline.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) X is acidic, Y is neutral, Z is alkaline.
(b) X is strongly acidic; Z is strongly alkaline.
Common mistakes: Not distinguishing between weak/strong; Wrongly calling pH 7 acid/alkali
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly classifies X (pH 3) as acidic.
B1 (a) · 1 mark · Correctly classifies Y (pH 7) as neutral.
B1 (a) · 1 mark · Correctly classifies Z (pH 12) as alkaline.
B1 (b) · 1 mark · Identifies X as strongly acidic (pH 0–3), Z as strongly alkaline (pH 11–14).
Worked solution
a) X is acidic (pH 3), Y is neutral (pH 7), Z is alkaline (pH 12).
b) X is strongly acidic (pH 0–3), Z is strongly alkaline (pH 11–14).