Acids

All acids have a pH value

• above 7

• below 7

• around 7

• exactly 7

Ethanoic acid is a weak acid because it

• does not contain any hydrogen ions

• has a very low pH

• is used in cooking and flavouring food

• is not fully ionised in water to form many hydrogen ions

When a hydrogen ion is lost from an acid, the resulting particle is called its conjugate base. Which of the following particles would be the conjugate base for the acid HSO₄^–?

• H₂SO₄

• HSO₄

• SO₄^–

• SO₄^2–

Acids have a ___________ taste and also turn __________ litmus paper __________.

• sour, red, blue

• bitter, red, blue

• sour, blue, red

• bitter, green, red

Acids dissolve in water to form solutions which

• conducts heat

• conducts electricity

• becomes an electrolyte

• to form mobile ions

Acids react with __________________ to form a salt and a gas which extinguishes with a 'pop' sound.

• alkalis

• bases

• carbonates

• reactive metals

Acids react with carbonates and hydrogen carbonates to form

• salt, water

• salt, water and carbon dioxide

• salt, carbonate

• salt, water and hydrogen

Acids are a group of chemical compounds which produces ______________ when dissolved in water

• hydroxide ions

• hydrogen ions

• proton

• hydrogen

The carbon dioxide gas produced by a chemical reaction can be tested with _________.

Choose the correct observation seen.

• limewater, a milky solution is seen

• burning splint extinguishes with a pop sound.

• limewater, a white precipitate is seen.

• glowing splint extinguishes with a pop sound.

The table shows some information about the colour changes of three indicators.

What colour would be observed if all three indicators were mixed together at pH 6?

• Blue

• Green

• Orange

• Yellow