Acids (T4)

Question 1

What is the pH of acids?

Answer 1

Less than 7

Question 2

How does the strength of an acid affect the pH?

Answer 2

The stronger the acid, the lower the pH number

Question 3

What colour does acid turn blue litmus paper?

Answer 3

Red

Question 4

What do acids do to universal indicator?

Answer 4

They turn universal indicator red if they are strong, and orange or yellow if they are weak

Question 5

What element needs to be present for a substance to be acidic and why?

Answer 5

• hydrogen (generally lots of it)
• this is because acidity requires aqueous substances with a large amount of hydrogen ions (H+)

Remember!! Hydrogen only has one electron. Acids are always sources of hydrogen ions.

Question 6

Acids are always sources of ……… ………

Answer 6

Acids are always sources of hydrogen ions

Question 7

Describe dilute acids and concentrated acids…

Answer 7

• dilute acids:
  Hydrochloric acid, sulphuric acid, nitric acid.
  Theirs bottles are labelled with the label ‘irritant’.
  If come into contact with skin can cause redness, blisters and a burning sensation.
• concentrated acids:
  Very corrosive.
  Can attack metals and destroy skin.

Question 8

List five acids you will find at home…

Answer 8

• ethanoic acid (vinegar)
• carbonic acid (fizzy drinks)
• tannic acid (tea)
• absorbic acid (vitamin c)
• citric acid (lemons)

Question 9

Acids react with most metals and a salt is produced, but unlike the reaction between acids and bases we don’t get any water. What do we get instead?

Answer 9

Hydrogen gas

Question 10

What is the general word equation for an acid reacting with metal?

Answer 10

Metal + acid > salt + hydrogen

Question 11

The salt produced by reacting a metal with acid depends upon the reactants. Show the word equations of zinc + sulphuric acid and magnesium + hydrochloric acid…

Answer 11

Zinc + sulphuric acid > zinc sulphate + hydrogen

Magnesium + hydrochloric acid > magnesium chloride + hydrogen

Question 12

What is the general word equation for acids reacting with metals?

Answer 12

Acid + metal > salt + hydrogen

Question 13

What is the word and chemical equation for copper reacting with hydrochloric acid?

Answer 13

Copper + hydrochloric acid > copper chloride + hydrogen

Cu(s) + 2HCl(aq) > CuCl2(aq) + H2(g)