Acids And Alkalis

Question 1

Properties of Acids

Answer 1

They are Liquids
They are Solutions of compounds in water
If concentrated they can be corrosive
Can taste sour (eg. vinegar and lemon juice)
They turn blue litmus paper red - an easy test for acid
Usually react to metals to form salts
They contain hydrogen ions (OH)
They turn universal indicator from green to red
Have a pH less than 7

Question 2

Properties of Alkalis

Answer 2

They feel soapy to the touch
They are soluble bases
Like acids, they can burn the skin
They turn red litmus paper blue - this is how you test for alkali
Contain hydroxide ions (OH)
They taste bitter.
Turns universal indicator from green to blue or purple

Question 3

Properties of Neutral Substances

Answer 3

Litmus paper is not affected by neutral paper.
Tend to be harmless
Universal indicator stays green

Question 4

Examples of common acids used in laboratories

Answer 4

Hydrochloride Acid (HCl)

Nitric Acid (HNO)

Sulphuric Acid (H2SO)

Question 5

Examples of common alkalis used in laboratories

Answer 5

Sodium Hydroxide (NaOH)

Ammonia ( NH3NH4OH)

Calcium Hydroxide (Ca(OH))

Question 6

Examples of neutral substances

Answer 6

Water

Sodium Chloride Solution (NACl)

Sugar solution (C6H12O6)

Question 7

How do we measure how strong it weak acids or alkalis are?

Answer 7

Measure using a pH scale.

A pH scale goes from 0-14.

Question 8

pH level below 7 is an …

Answer 8

Acid

The strongest acid has pH 0

Question 9

pH level above 7 is an ….

Answer 9

Alkali

The strongest alkali has pH 14

Question 10

A neutral substance has a pH level of ….

Answer 10

pH 7 (Like water)

Question 11

What are indicators?

Answer 11

Indicators tell us if a substance is an acid or an alkali by changing colour depending on what it is

Question 12

Examples of indicators are?

Answer 12

Litmus Paper (can be red or blue) - acids turn blue litmus paper red and alkalis turn red litmus paper blue

Universal indicator is a liquid indicator- acids give the colours red to yellow, neutral solutions give a green colour and alkalis give the colours blue to purple

Question 13

Examples of acids and alkalis

Answer 13

Stomach acid - strong acid (1)

Rain water - weak acid (5)

Washing up liquid - weak alkali (8)

Oven cleaner - strong alkali (13)

Lemon juice - strong acid (2)

Water - neutral (7)

Question 14

What happens when acids and alkali react

Answer 14

They make a salt and water reaction and this reaction is called a neutralisation reaction

Question 15

Give an example of a neutralisation reaction

Answer 15

Hydrochloric acid (an acid) + sodium hydroxide (an alkali) = sodium chloride (a salt) + water