![3. Below are 3 diagrams that represent the ions of each cup at three
different stages of the experiment. Match the correct method part to
each diagram.
Titration | experiment reflection
Complete Activity 5
[PART 1]
[PART 2] [PART 3]](https://image.slidesharecdn.com/acidsandbasesppt-250729035104-02df4095/85/Acids-and-Bases-PPT-for-EMG-program-grade-9-38-320.jpg)
Acids and Bases PPT for EMG program grade 9
- 2. Acids & Bases AGENDA Objectives Page Numbers Acids, Bases & Neutralisation pH Scale & Indicators Pipette Titration Scientific Enquiry Skill: Evaluating Risks of an Experiment Acid Reactions with Oxides & Carbonates
- 3. | Acids, Bases & Neutralisation
- 4. Acids & Bases | warm-up How many household acids and bases can you name? One half of the class will write acidic substance, the other half, basic. Consider: - foods - drinks - cleaning products ACIDS BASES coffee... olive oil...
- 5. Proton 1 H+ Acids & Bases | acids Acids donate protons. A proton is a hydrogen atom without an electron. The more protons, the stronger the acid.
- 6. Acids & Bases | bases Bases attract protons. A base has a negative charge to attract positive protons. Hydroxide ions are a strong attractor of protons. When hydroxide ions come together with protons they form neutral water. This type of reaction is called neutralisation.
- 7. Neutralisation | acid-metal reaction An acid reacts with a metal to form a salt and hydrogen gas.
- 8. Neutralisation | naming salts A salt name depends on the acid and metal that they are made from. Acid Naming • sulfuric acid → ...sulfate • nitric acid → ...nitrate • hydrochloric acid → ...chloride Metal Naming The metal name stays the same. zinc... iron... sodium... • zinc + hydrochloric acid -> ______________ + hydrogen • sodium + nitric acid -> ______________ + hydrogen • iron + sulfuric acid -> ______________ + hydrogen zinc chloride sodium nitrate iron sulfate
- 9. | Acid Reactions with Oxides & Carbonates
- 10. Acid Reactions | displacement Neutralisation reactions are displacement reactions. We can say “sodium displaces hydrogen” in this reaction.
- 11. Acid Reactions | oxides When acids react with metal oxides a salt and water are produced. Describe each displacement.
- 12. Acid Reactions | carbonates When an acid reacts with a metal carbonate, a salt, water and carbon dioxide gas is produced.
- 13. | pH Scale & Indicators
- 14. pH Scale | introduction pH stands for “power of hydrogen” and is a measure of the concentration of protons. If a substance has a pH less than 7, then it is acidic. If a substance has a pH more than 7, then it is basic.
- 15. pH Scale | acid / base strength strong acid weak acid weak base strong base neutral Define the following substances by their strength.
- 16. pH Scale | indicator types pH indicators show a change in colour at specific pHs. Universal indicators show a gradual change in colour. Acid / Alkali indicators change between 2 colours.
- 17. pH Scale | universal indicator Universal indicator shows a greater range of pH values, but can be less accurate. Universal indicator needs to be used with a colour chart, to help identify the pH of something. Which pHs do you think it would be difficult to tell the difference between?
- 18. pH Scale | acid / alkali indicators Acid / Alkali indicators only identify 1 pH level (sometimes 2), but they are more accurate. Three common acid / alkali indicators are: Indicator Name Colour in Acid Colour in Base
- 19. pH Scale | digital indicators Digital pH indicators can identify a range of pH values and they are accurate. A pH meter converts the potential difference between 2 electrodes into a pH value.
- 20. | Pipette Titration Evaluating Risk
- 21. Titration | evaluating risk (labels) Hazard symbols inform about the specific risks of chemicals. toxic irritant / harmful corrosive danger to the environment flammable
- 22. Titration | evaluating risk (other) Wearing appropriate clothing and your behaviour determine your level of risk. The student’s hair is loose. Identify the risks in the picture. The chemicals are on fire. Fumes are produced by the reaction.
- 23. Titration | evaluating risk (other) Wearing appropriate clothing and your behaviour determine your level of risk. Too much exposed skin. Identify the problems with this outfit. Clothes are too loose. Unstable footwear. Face is unprotected.
- 24. Titration | evaluating risk (other) Wearing appropriate clothing and your behaviour determine your level of risk. Tripping Hazards Identify the problems. Food & Drink Playing
- 25. Titration | identifying hazards Complete Activity 1 of your Investigation Handout. a. Look around the classroom and write down something that could be dangerous when conducting the experiment. Answers will vary but may include... - Bags left on the ground. - Some crazy student. - Student with untied hair. - Inapropriate clothing. - Some food or drink.
- 26. Titration | identifying hazards Complete Activity 1 of your Investigation Handout. b. Write down a possible solution to the hazard. Answers will vary but may include... - Tidy away all bags / food / drink. - Tie up the hair. - change the clothes / keep inappropriately dressed student away from the experiment. - Put the overly excited student in the corner.
- 27. Titration | identifying hazards Complete Activity 1 of your Investigation Handout. c. Share this hazard and your solution with the teacher. Did the teacher agree with your solution? __________________ d. If not, what did the teacher suggest? Answers will depend on the teacher.
- 28. Titration | identifying hazards Complete Activity 1 of your Investigation Handout. e. Hydrochloric acid and sodium hydroxide are used in this experiment. The bottles contain the following two labels: What do they mean? corrosive harmful / irritant
- 29. Titration | identifying hazards Complete Activity 1 of your Investigation Handout. f. Name two things that should be done to protect yourself when working with strong acids / bases? • wear gloves • cover areas of exposed skin • wear goggles (if splashing could happen)
- 30. Titration | introduction You will make observations of 3 different indicators while performing a neutralisation reaction. Get into your groups now.
- 31. Titration | materials Collect the following materials from the teacher. - 4 plastic cups - 1 pipette - 3 stirring sticks - 60 ml of sodium hydroxide - 5 ml of hydrochloric acid - 5 drops of each indicator (methyl orange / universal / phenolphthalein)
- 32. Titration | experimental setup Complete Activity 2. 1. Measure 20 ml of sodium hydroxide solution into three of the plastic cups. 2. Measure 5 ml of hydrochloric acid into the 4th cup. 3. Add 5 drops of each indicator into the 3 NaOH filled cups separately. 4. Complete the table to show your observations of the indicators in the basic solution. Indicator Type methyl orange universal phenolphthalein Observation Yellow Purple Pink Your answers may differ slightly, that’s ok.
- 33. Titration | experimental setup Complete Activity 3. • From the pipette add one drop of acid to one cup. • Stir the cup and observe if there is a colour change. • If no colour change, go back and repeat steps a) and b) until there is. Indicator Type methyl orange universal phenolphthalein Observation Drops Number orange green transparent Your answers may differ slightly, that’s ok. 10 - 15
- 34. Titration | experimental setup Complete Activity 4. 1. Divide the remaining acid among the three cups, write down if there is any further changes to their colour in the table below: Indicator Type methyl orange universal phenolphthalein Observation red red no change Your answers may differ slightly, that’s ok.
- 35. Titration | experimental setup Complete Activity 5. “One drop of HCl is approximately 0.05 ml.” 1. If the above statement is true, how many ml of hydrochloric acid neutralised 20 ml of sodium hydroxide according to your observations? • If 10 drops, 1 ml + (0.05 ml x 10) = 1.5 ml • If 11 drops, 1 ml + (0.05 ml x 11) = 1.55 ml • If 12 drops, 1 ml + (0.05 ml x 12) = 1.6 ml • If 13 drops, 1 ml + (0.05 ml x 13) = 1.65 ml • ...
- 36. Titration | experimental setup Complete Activity 5. 2.a) According to your results, which indicator showed a change in colour (to green for universal) at the lowest pH? Answers will vary, but... methyl orange changes between yellow and orange at ≈ pH 5 phenolphthalein changes between pink and transparent at ≈ pH 8 universal indicator changes to green at ≈ pH 7 ... if you put methyl orange, you conducted your experiment like a pro! Hint: the one that needed the most acid.
- 37. Titration | experimental setup Complete Activity 5. 2.b) Which indicator showed the greatest range of pH values in its colour changes? universal indicator
- 38. 3. Below are 3 diagrams that represent the ions of each cup at three different stages of the experiment. Match the correct method part to each diagram. Titration | experiment reflection Complete Activity 5 [PART 1] [PART 2] [PART 3]
- 39. Next Week: Nutrition & Digestion Please bring your BIOLOGY textbooks