Year 10 Science · Unit 2 · Lesson 2
Foundation Worksheet
Learning Goals
Read the graph
Study the bar chart showing the pH of eight common substances, then answer the questions below.
Data: Standard chemistry reference values (Atkins, Physical Chemistry, 2023)
(a) List all substances from the chart that are acidic (pH below 7).
(b) Which substance shown is approximately neutral? What pH value is considered neutral?
(c) Both bleach and drain cleaner are alkaline. Which is more strongly basic, and how does the pH scale tell you this?
Fill the gap
Choose the correct word from the word bank to complete each sentence about acids and bases.
The pH scale runs from 0 to 14. A substance with a pH below 7 is , while a substance with a pH above 7 is . Pure water has a pH of and is described as .
Acids produce an excess of in solution, while bases produce an excess of . Acids typically taste , while bases typically taste .
The indicator turns red in acids and blue in bases. Concentrated acids and bases carry the hazard symbol because they can destroy living tissue.
1. Hydrochloric acid (HCl) is found in stomach acid with a pH of about 1–2. State whether stomach acid is strongly or weakly acidic, and explain what the low pH value tells you about the concentration of H⁺ ions.
2. You test an unknown household substance with litmus paper and the paper turns blue. What can you conclude about the pH of the substance? Is it an acid, base, or neutral? Give a possible example of what the substance might be.
Wrap Up
In one sentence, what was the main idea of this lesson?