RECAP: One way to classify chemical compounds – is by their bonding.

Compounds can have ________________________ bonds.

Other ways to classify compounds: Chapter 5.1 Acids and Bases (p220 – 224)

Many familiar compounds are acids or bases. Can you think of some now? Some common acids are: _______________________________________Some common bases are: _______________________________________

Properties of acids and bases (p229)

Acids and bases can both be very corrosive (which means _____________ ___________). Never identify an acid or base by _______ or________.

Swedish chemist, Cervantes Arrhenius, suggested:- acids are substances that release hydrogen (H+) ions in solution. - Bases release hydroxide (OH-) ions in solution.

How do we measure how acidic or basic a solution is?

1) pH Scale

The strength of acids and bases are measured _____________________.

What is the pH scale?

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

pH < 7

pH = 7

pH > 7

Remember ____ BEFORE ____

Some pH’s of common items

Note: the more acidic a substance, the ___________ the pH.

The pH scale is a LOG scale. Each unit of change represents a 10x change in the level of acidity or alkalinity of a substance.

- This means a pH of 2 is 10x more acidic than a pH of 3.- A pH of 11 is 100x more alkaline than a pH of 9!!

Let’s practice!!

1) Compare a pH of 4 and a pH of 2.

2) Compare a pH of 11 and a pH of 7.

How is pH determined?

Chemical indicators are substances that change colour in the presence of H+ ions (acids) and OH- ions (bases). They can tell us the approximate pH of a solution as the indicators change colour based on the pH of the solution they are placed in.

A couple examples for indicators

The most common indicator is litmus paper. There are two colours to litmus paper: blue = _____________ ; red = ____________

Other common indicators include phenolphthalein and bromothymol blue.

NOTE: Acids and bases only behave like acids or bases when dissolved in water. You will regularly see a (aq)=aqueous on acids or bases, meaning they are dissolved in water.

Instant practice. Using Figure 5.2 (p222 BC Science 10) lists pH values of common substances. Figure 5.6 p 224 illustrates commonly used acid-base indicators and their colour changes. Refer to both of these charts to answer the following questions.

1. Complete the following table:Substance pH Classification Indicator Colour

Bleach Phenolphthalein

Water Methyl orange

Lemon Bromothymol blue

2. Answer questions # 1 -5 in the Reading Check on page 225.

How to identify ACIDS (p 225)- You can sometimes identify an acid by its ___________________. - Many compounds only take on acid properties (or behave like an acid

or a base) when they have been _____________________. - This is why you will see an (aq). It means aqueous or “dissolved in

water to make a solution”.

Naming Acids- The chemical formulas for acids are usually written with an H on the

LEFT side of the formula e.g. HCl(aq) - EXCEPTION: If an acid contains the element Carbon, the H is written on

the RIGHT side. E.g. acetic acid (vinegar) CH3COOH(aq)- If a chemical formula is written with (aq) it needs to be named an acid.

Rule 1: Hydrogen – ide becomes hydro-ic acidNon-Oxygen Acids

HCl (aq)HCN (aq)HF (aq)For more examples, see figure 5.3 p 225

Rule 2: Hydrogen – ate becomes -ic acidOxygen Acids (1)

HNO3 (aq)

H2SO4 (aq)

H2CO3 (aq)

Rule 2: Hydrogen – ite becomes -ous acidOxygen Acids (2)

HClO2 (aq)

H2SO3 (aq)

For more examples, see figure 5.4 p 225

Bases (p227)- Almost always end with an OH- The OH is written on the RIGHT side of the formula- Bases that are highly reactive are called caustic

Some examples of bases:NaOHMg(OH)2

Ca(OH)2

Salts (Chap 5.2 p234-236)

A salt is any compound that:- Forms a product when and acid + base react (neutralization reaction)

Some examples of salts:CuCl2 General Salt Notes:

-are ionic-none contain H+-none contain OH-

MgCl2

LiBr

Instant Practice:Formula Name Ionic or Acid, Base, Salt

Covalent? Or None? Potassium nitrate

CH3COOHCH4

Lithium hydroxideH2CO3

Sodium carbonateBa(OH)2

Sulphur dioxide