Compounds

Compounds are groups of two or more elements that are bonded together.

Common Chemical Compounds

NaCL How many Sodium atoms?

How many Chlorine atoms?

Common Chemical Compounds

C6H12O6 How many Carbon atoms?

How many Hydrogen atoms?

How many Oxygen atoms?

Common Chemical Compounds

H20How many Hydrogen atoms?

How many Oxygen atoms?

Common Chemical Compounds

NaHCO3How many Sodium atoms?

How many Hydrogen atoms?How many Carbon atoms?

How many Sodium atoms?

Acids and Bases

What are Acids? Acids are

common Some are

dangerous and can burn your skin

Some are safe to eat and drink

Stomach acid helps digest food explosion

Acids

Definition • A group of compounds which behave similarly• All have low pH• Turn Litmus paper RED• All donate H+ ions in aqueous solution

Examples• Hydrochloric HCl• Sulfuric H2SO4

• Nitric HNO3

Acids

A dilute acid has lots of water and a small amount of acid

A concentrated acid has lots of acid and not much water so must be handled carefully

A strong acid releases lots of H+

A weak acid releases fewer H+

What are Bases (Alkalis)?

In our home we often use bases to clean things. Eg Bleach and toothpaste

Some things are not acids or bases, we say that they are neutral. Eg Water

Bases

Definition• A family of compounds that behave

similarly• Have a high pH• Turn litmus BLUE• All donate OH-

Examples• Ammonia NH3

• Sodium Hydroxide NaOH

Measuring acid strength?

To decide if something is an acid or a base we can use an indicator.

Litmus and Universal Indicator are examples of indicators.

They change colour depending on if they are in an acid or a base.

Working with Indicators

Red litmus turns BLUE in the presence of Bases

Blue litmus turns RED in the presence of acid

Acids and bases react together in a NEUTRALISATION reaction

Acid Reactions

Acid + Base Salt + Water

Acid + Metal Salt + Hydrogen

Antacid – (Anti-Acid)

Acid + Base = Neutral Solution

Stomach Acid Mylanta – Base The two together

make a neutral solution.

Demonstration

NaOH + HCL NaCL + H20Base Acid Neutral Solution

Turns blue in indicator

Turns red in indicator

Turns green in indicator