Question detail
Exam scenario ALC-0e2ac640: Use practical decision making to explain how the evidence supports the objective "Use Kw to calculate hydrogen ion or hydroxide ion concentrations." in pH and Kw (A-level only).
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At a glance
Question
Type
exam_style
Style
Topic
Acids and bases (A-level only)
Question
Exam scenario ALC-0e2ac640: Use practical decision making to explain how the evidence supports the objective "Use Kw to calculate hydrogen ion or hydroxide ion concentrations." in pH and Kw (A-level only).
Answer
For ALC-0e2ac640, a strong answer should use practical decision making to address pH and Kw (A-level only). It should identify the chemical principle in the objective "Use Kw to calculate hydrogen ion or hydroxide ion concentrations.", apply the evidence from the prompt, and finish with a specific conclusion. This makes the question distinct from nearby items while preserving the same A-Level Chemistry curriculum coverage.
Explanation
For ALC-0e2ac640, a strong answer should use practical decision making to address pH and Kw (A-level only). It should identify the chemical principle in the objective "Use Kw to calculate hydrogen ion or hydroxide ion concentrations.", apply the evidence from the prompt, and finish with a specific conclusion. This makes the question distinct from nearby items while preserving the same A-Level Chemistry curriculum coverage.
Common mistake
Kw Calculation Error
Students often confuse the relationship between Kw and hydrogen ion concentration, leading to incorrect calculations.
To calculate the hydroxide ion concentration from Kw, use the formula Kw = [H⁺][OH⁻]. Substitute the value of Kw (1.0 x 10⁻¹⁴ at 25°C) and the known hydrogen ion concentration to find the hydroxide ion concentration. For example, if [H⁺] = 1.0 x 10⁻⁷ mol/dm³, then [OH⁻] = Kw / [H⁺] = (1.0 x 10⁻¹⁴) / (1.0 x 10⁻⁷) = 1.0 x 10⁻⁷ mol/dm³.
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