Q1. What do you understand by the term pH?
Answer: pH measures the acidity or alkalinity of a solution. It is a standard used to estimate the concentration of hydrogen ion (H+) concentration. It is equivalent to the negative log of hydrogen ion (H+) concentration.
pH = – log [H+]
Q2. What do you understand by the term pOH?
Answer: pOH measures the acidity or alkalinity of a solution. It is a standard used to estimate the hydroxide ion (OH–) concentration. It is equivalent to the negative log of hydroxide ion (OH–) concentration.
pH = – log [OH–]
Q3. What does the pH of a solution signify?
Answer: A pH of solution signifies the concentration of hydrogen ion (H+) in moles per litre.
Q4. What is the pH of an acidic solution?
Answer: The pH of an acidic solution is less than 7.
Q5. What is the pH of an alkaline solution?
Answer: The pH of an alkaline solution is more than 7.
Q6. What is the pH of a neutral solution?
Answer: The pH of a neutral solution is equal to 7.
Q7. What is a universal indicator?
Answer: A universal indicator is a pH indicators mixture that gives distinct colours at distinct pH values of the entire scale.
Q8. What is the effect of dilution on the pH of an acidic solution?
Answer: pH of an acidic solution increases on dilution.
Q9. What is the effect of dilution on the pH of an alkaline solution?
Answer: pH of an alkaline solution decreases on dilution.
Q10. What happens to the pH of the solution if a little acid is added to the water?
Answer: When an acid is added to the water, the hydrogen ion concentration will increase. Thus, its pH would decrease.
Q11. Will the pH of 0.1 M acetic acid be the same as that of 0.1 M hydrochloric acid?
Answer: No, the pH of 0.1 M acetic acid will not be the same as that of 0.1 M hydrochloric acid. Acetic acid is a weak acid. It does not ionise completely, i.e. produces lesser hydrogen ions. Thereby its pH will be more.
Q12. What is an acid-base indicator?
Answer: An acid-base indicator is an organic compound that indicates the change in colour with the change in pH value.
Example: Phenolphthalein, Litmus paper, and Red Cabbage Juice.
Q13. Which of the following solutions has lower pH: 0.1 M hydrochloric acid or 0.1 M acetic acid?
Answer: The 0.1 M hydrochloric acid pH will be less than the 0.1 M acetic acid. Hydrochloric acid is a strong acid. It ionises completely and produces a large number of hydrogen ions. Thus its pH will be less.
Q14. What is the pH indicator chart?
Answer: The pH indicator chart is a standard that displays the colours over the entire pH range. It is used to assess the acidity or alkalinity of a solution.
Q15. What is the pOH of a solution if its pH is 1?
Answer: Given
pH = 1,
We know that sum of pH and pOH is equal to 14,
pH + pOH = 14
pOH = 14 – pH
pOH = 14 – 1
pH = 13.
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