中文（繁體）
中文（简体）
English
S4 Chemistry: Neutralisation and Titration (Paper 1: basics)
S4 Chemistry: Neutralisation and Titration (Paper 1: basics)
Ten basic items on neutralisation products, moles from concentration and volume, 1 to 1 and 1 to 2 mole ratios, exothermic neutralisation, phenolphthalein colour and cm3 to dm3 conversion.
Direct answers Answers in order: sodium chloride and water, 2.50 x 10-3 mol, 0.010 mol, 0.100 mol, 25.0 cm3, negative because heat is released, neutral, pink to colourless, 0.125 mol, and the volume was not converted so the answer is 1000 times too large.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S4 Chemistry: Neutralisation and Titration |
| Level | S4 |
02 Questions (10 items)
- FoundationWhat two substances are formed when sodium hydroxide solution is neutralised by hydrochloric acid?
- FoundationHow many moles of sodium hydroxide are in 25.0 cm3 of 0.100 mol/dm3 sodium hydroxide solution?
- FoundationFrom NaOH + HCl to NaCl + H2O, how many moles of sodium hydroxide react with 0.010 mol of hydrochloric acid?
- IntermediateFrom H2SO4 + 2NaOH to Na2SO4 + 2H2O, how many moles of sodium hydroxide react with 0.050 mol of sulphuric acid?
- IntermediateWhat volume of 0.200 mol/dm3 sodium hydroxide neutralises 25.0 cm3 of 0.200 mol/dm3 hydrochloric acid?
- IntermediateIs the enthalpy change of a neutralisation reaction positive or negative?
- ChallengeAt 25 degrees Celsius, is a solution of pH 7 acidic, alkaline or neutral?
- ChallengeUsing phenolphthalein, how does the colour change at the end point when hydrochloric acid is added to sodium hydroxide solution?
- ChallengeHow many moles of solute are in 250 cm3 of a 0.500 mol/dm3 solution?
- Error redoA student multiplies 0.100 by 25.0 and reports 2.5 mol. What has gone wrong?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | Sodium chloride and water | An acid and an alkali always give a salt and water, and here the salt is sodium chloride. |
| 2 | 2.50 x 10-3 mol | Moles equal concentration times volume in dm3, so 0.100 times 0.0250 gives 2.50 x 10-3. |
| 3 | 0.010 mol | The equation gives a 1 to 1 mole ratio, so the moles are equal. |
| 4 | 0.100 mol | The mole ratio is 1 to 2, so doubling 0.050 mol gives 0.100 mol. |
| 5 | 25.0 cm3 | With a 1 to 1 ratio and equal concentrations the two volumes are equal. |
| 6 | Negative, because the reaction releases heat | Neutralisation gives out heat and the temperature rises, so the enthalpy change is negative. |
| 7 | Neutral | At 25 degrees Celsius pH 7 means the hydrogen ion and hydroxide ion concentrations are equal. |
| 8 | From pink to colourless | Phenolphthalein is pink in alkaline solution and turns colourless once the acid is in excess. |
| 9 | 0.125 mol | 250 cm3 is 0.250 dm3 and 0.500 times 0.250 gives 0.125 mol. |
| 10 | The volume was not converted to dm3, so the correct answer is 2.50 x 10-3 mol | Concentration is in mol/dm3, so cm3 must be divided by 1000 first, otherwise the answer is 1000 times too large. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
For every item write concentration times volume to get moles, compare the mole ratio, then give the answer with its unit.Tutor Registration →
Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.