Testing the properties of acids and bases
Test dilute hydrochloric acid and sodium hydroxide solution with zinc, marble chips, litmus and phenolphthalein to discover how acids and bases behave.
Core concept
Acids react with metals and carbonates and turn blue litmus red; bases turn red litmus blue
Topic: Acids, bases and salts
acid: A substance that tastes sour, like lemon juice or vinegar. It turns blue litmus red. All key words and base: The opposite of an acid, like soap or baking soda solution. It feels slippery and turns red litmus blue. All key words have typical properties that chemists use to recognise them. Acids turn blue litmus red, react with reactive metals such as zinc to give hydrogen gas, and react with carbonates such as marble to give carbon dioxide: A gas we breathe out. Plants take it in to make their food. All key words. Bases (alkalis) turn red litmus blue and turn phenolphthalein pink. In this experiment you test one solution: A mixture where one substance has dissolved completely in a liquid, like salt water. All key words of each with several reagents.
What you will learn
- Describe the reactions of dilute acids with metals and carbonates.
- Use litmus and phenolphthalein to tell acids and bases apart.
- Name the gases produced when acids react with zinc and with marble.
Before you start
- Know the pH scale. Try "How acidic is it? The pH scale" first.
Materials
- Dilute hydrochloric acid
- Dilute sodium hydroxide solution
- Zinc granules and marble chips
- Blue litmus, red litmus and phenolphthalein indicator
Equipment
- 6 test tubes in a rack
Procedure
- Put dilute hydrochloric acid in three test tubes and sodium hydroxide solution in the other three.
- Add a different test reagent to each tube: zinc granules, marble chips, litmus or phenolphthalein.
- Observe each tube and record whether gas is given off or the colour changes.
How this simulation is simplified
- Each reaction is shown straight away. Real reactions take a few seconds to start.
- Litmus is shown as a few drops of litmus solution instead of litmus paper.