Other alkaline solutions
4 marks · NormalThe following table shows the concentration of hydrogen ions in different solutions.
| Solution | [H^+] (mol/dm³) |
|---|---|
| A | 1.0 × 10^{-2} |
| B | 1.0 × 10^{-6} |
| C | 1.0 × 10^{-4} |
| D | 1.0 × 10^{-8} |
Which solution is the most acidic? Explain your answer.
Which solution is likely to have a pH above 7? Give the letter.
State the relationship between hydrogen ion concentration and acidity.
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) A is most acidic because it has the highest H^+ concentration. · must show Identifies A, Mentions highest H^+ = most acidic
(b) D · must show Correct letter: D
(c) The higher the H^+ concentration, the greater the acidity.
Common mistakes: Selecting highest pH instead of highest H^+ for a; Misstating the relationship for c
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies solution A.
M1 (a) · 1 mark · Explains that highest H^+ means most acidic.
B1 (b) · 1 mark · States the correct letter: D.
B1 (c) · 1 mark · States correct relationship between H^+ and acidity.
Worked solution
a) A is the most acidic, as it has the highest hydrogen ion concentration.
b) D, because the lowest H^+ concentration means the pH is above 7 (alkaline).
c) The higher the H^+ concentration, the greater the acidity.