Year 10 Science · Unit 2 · Lesson 4
Challenge Worksheet
Learning Goals
Find the mistake
A student wrote this answer
"When an acid and a base neutralise each other, both substances are completely destroyed and disappear. The acid ceases to exist and so does the base, that's why we call it neutralisation, because both chemicals are annihilated. The products of neutralisation are therefore nothing at all, just neutral water. The salt that 'appears' in equations is just a simplified way of writing that the chemicals cancelled out."
1. Identify the two key scientific mistakes in this student's answer.
2. Write a corrected version of the student's explanation. Your answer must include: what actually happens to the H⁺ and OH⁻ ions, what the two real products of neutralisation are, and a specific example (name a real acid and base and their salt product).
3. Why is it easy to believe that acids and bases "destroy each other"? What everyday observation might lead someone to this misconception? Explain how the law of conservation of mass shows this cannot be true.
1. Predict the name of the salt formed when sulfuric acid reacts with sodium hydroxide. Explain the naming rule you used: which part of the salt's name comes from the acid, and which part comes from the base?
2. After a neutralisation reaction between equal quantities of HCl and NaOH, a student measures the pH and finds it is exactly 7. She then evaporates all the water from the product. Describe what solid remains and explain how this demonstrates that the acid and base did not "destroy each other" but instead formed new substances.
Wrap Up
In one sentence, what was the main idea of this lesson?