1. Classic Chem The base-ics about bases 9-12 Science Std: Chem 5a

2. We started with: Solutions Equations 2H 2 + O 2 2H 2 O Definition of Acid and Base and pH And properties of acids

3. One last area to cover… What is a base Remember that: A base is: A compound that increases the concentration of hydroxide ions in a water solution OH -

4. And that : You know it’s a base By using a pH meter This is one way to know the actual pH value

5. Now its time to look at : How you can tell it is a base There are 5 ways to tell something is a base Sound familiar? – it will…

6. What is a base? The first property: Bases mixed in water have a bitter taste But like acids – don’t taste everything to test Unsweetened “Bakers” chocolate has a bitter taste

7. Why not? Just like acids Bases can burn your mouth Just as fast as an acid can If the pH is high enough… 7 14

8. Why not? But there are some bases you can taste… Brussel sprouts So a Bitter taste is a sign that it is a base Spinach

9. Remember the difference Acids are sour Bases are bitter Lemons Soda Water

10. What is a base? The second property: Bases change the color of acid/base indicators Blue to Red - AcidRed to Blue - Base

11. What is a base? The second property: And yes, cabbage can be used as a pH indicator for bases too As for plants – they like slightly acidic soil (pH 7-5)

12. What is a base? The third property: A watered down basic solution feels slippery What is something that feels slippery?

13. What is a base? The third property: Soaps Soaps have a slippery feel because they make a dilute basic solution

14. What is a base? The fourth property: Bases react with acids to make salts and water Just like we covered with acids The cation (+) comes from the base

15. What is a base? The fourth property: An example: Sodium Hydroxide (Base) Hydrochloric Acid Na OH H Cl

16. The fourth property: When you mix these in water… The sodium and hydroxide split and make ions And the hydrogen and chlorine split and make ions Na OH H Cl What is a base?

17. The fourth property: Once the ions split The sodium and chlorine get together And the hydrogen and hydroxide get together Na OH H Cl What is a base?

18. The fourth property: And what do you get? Sodium Chloride (Salt) And H 2 O (Water) Na OH H Cl What is a base?

19. The fifth property: Some bases conduct electricity Just like some acids What is a base?

20. The fifth property: If the base has an ionic bond The ions in the base Will conduct electricity just like acids Na OH + - What is a base?

21. And that’s the list Review the 5 properties of bases 1. Bases in water have a Bitter Taste

22. And that’s the list Review the 5 properties of bases 2. Change the color of pH indicators

23. And that’s the list Review the 5 properties of bases 3. Dilute solutions are Slippery

24. And that’s the list Review the 5 properties of bases 4. React with acids to make water and salts

25. And that’s the list Review the 5 properties of bases 5. Some bases conduct electricity

26. So what are the differences… What is the same for acids and bases Acids Bases Properties Change color of Indicators Make Salt and Water Some Conduct Electricity

27. So what are the differences… Acids Bases Properties Taste Sour Bitter Other properties React with metals to make gases Dilute solutions are slippery What is different for acids and bases

29. Your Homework….. Review properties of acids and bases to prepare for lab