1. Acids & Bases

2. Goals To determine the difference between Acids & Bases
Discuss the importance of studying Acids & Bases

3. HCl(g)
NaOH(s)
When an IONIC compound is placed in water, it will break apart into two ions. If one of those ions is H+... The solution is acidic. If one of the ions is OH-... The solution is basic.

4. Acidic solution
Alkaline solution

5. Formulas - Acids
In general, acids are identified by the hydrogen in the front of its chemical formula. For example, the formula for hydrochloric acid is HCl
Others are: Sulfuric acid H2SO4; Carbonic acid H2CO3; and nitric acid HNO3.
Some exceptions to this rule are some organic acids—such as acetic acid (CH3COOH)—have their formulae designated according to their structure.

6. Formulas - Bases
Bases can often be identified by the OH term in the end of their chemical formula, as seen in sodium hydroxide NaOH, magnesium hydroxide Mg(OH)2 and potassium hydroxide KOH.
There are some exceptions to this rule: ammonia gas NH3
Some organic acids have formulae that make them look like bases. Acetic acid (CH3COOH) for example.

7. The Arrhenius theory:
Acids dissolve in water to produce hydrogen ions, H+ (more corrrectly, the hydronium ion H3O+)
Bases produce the hydroxide , OH- ions.
This theory, while essentially correct, has been superseded by the Brønsted-Lowry theory

8. Characteristics - differences
Acids
Tastes sour
Turns litmus paper red
React with some metals to give off H2 gas.
React with carbonates to produce CO2 gas
pH of 0 – 7
Have an excess of H+ ions in solution.
Bases
Tastes bitter
Turns litmus paper blue
Feels slippery to the touch
pH of 7 to 14
Have an excess of OH- ions in solution.

9. Characteristics - similarities
Both conduct electricity
Acids and bases react together to form salts and water only. The process is called neutralization
NaOH + HCl H2O NaCl
Both acids and alkalis cause colour changes in certain substances called indicators, such as litmus:

10. Identifying Acids and Bases
Acids have a ph from 0-7
Lower pH value indicates a stronger acid.
Bases have a pH from 7-14
Higher pH value indicates a stronger base.

11. Definitions of Acids and Bases
An acid is a substance that breaks into ions in an aqueous solution.
A Base (alkaline) is a substance that breaks into ions in an aqueous solution.
Note: aqueous solution is any solution where is the solvent.

12. Characteristics Of Acids
Acids can be characterized by:
A sour taste.
It turns blue litmus paper red
It tastes sour. Try drinking lemon juice (citric acid)

13. Characteristics of Bases
A Base is characterized by:
A bitter taste. (Milk of Magnesia)
It feels slippery. (Soapy Water)
It turns Red Litmus Blue.

14. Mini-quiz to check your understanding 1
Mini-quiz to check your understanding 1. What element is in most acids and bases?
Water
Hydrogen
Sulfur

15. 2. Which pH indicates the material is acidic?
5.0
7.0
9.0

16. 3. Why should you be careful dealing with acids?
They can eat your skin away
They can cause an upset stomach
They smell real bad

17. 5. Which is a base?
CH3COOH
NaOH
NaCl

18. 6. What can a gardener do if the soil is too acidic?
Add a base such as lime or chalk to reduce acidity
Add lemon juice to reduce the acidity
Add salt (NaCl) until the soil becomes a base

19. What is the pH scale?
The pH scale measures how acidic or basic a solution is.

21. The pH scale
The pH scale is the concentration of hydrogen ions in a given substance.
“the power of Hydrogen”

22. Did we Miss something?? What happens when the pH of a substance is 7?
Ans: A pH level of 7 indicates a Neutral Substance i.e: Water!

23. Test Your Knowledge What is the range of an ACID on the pH scale?
Ans: 0-7
What is the range of a BASE and what is another name for a BASE?
Ans: 7-14, Alkaline

24. Why Learn about Acids & Bases?
What do you think is the pH level of Toronto tap water?
The pH of a swimming pool must be checked periodically. Why?
Is it important for Lakes & Rivers to maintain a certain pH?

25. Naming Acids Binary acids HF hydrofluoric acid HBr Hydrobromic acid HI
HCl

26. Acids with polyatomic ions
H2SO4 Sulphuric acid
HNO3 Nitric Acid
H2CO3 Carbonic Acid

27. Acid-Base Indicators
Certain chemicals have the special property of appearing in different colours depending on the pH of the solution they are in.
Such chemicals are known as acid-base indicators
A couple of drops of indicator in a solution will indicate its pH.

28. Three commonly used indicators.

30. Neutralization Reactions
What would happen if an acid and a base were mixed up?
What would happen if a hydrogen ion (H+) from an acid reacted with a hydroxide ion (OH-) from a base? 

31. Neutralization - reaction of an acid and base forming a salt and water.
HCl  +  NaOH 
  NaCl  +  HOH
Salts - composed of the positive half of a base and the negative half of an acid.
Question:
  What acid and base react to produce each of these salts?
CaSO4       NH4NO3       CaCl2