C7-Acids, bases, and salts

What are the characteristic properties of acids in relation to indicators?

Acids turn litmus red and methyl orange red.

What reaction occurs when acids react with metals?

Acids react with metals (e.g., Mg, Zn) to produce a salt and hydrogen gas.

What happens when acids react with bases?

Acids react with bases (oxides/hydroxides) to produce a salt and water (neutralisation).

What do acids produce when they react with carbonates?

Acids produce a salt, water, and carbon dioxide gas when reacting with carbonates.

What are bases?

Bases are oxides or hydroxides of metals.

What is an alkali?

Alkalis are soluble bases, such as NaOH and KOH.

What is the effect of bases on indicators?

Bases turn litmus blue and methyl orange yellow.

What is the pH scale for a neutral solution?

A neutral solution has a pH of 7.

What does a pH lower than 7 indicate?

A pH lower than 7 indicates an acidic solution.

What does a pH higher than 7 indicate?

A pH higher than 7 indicates an alkaline solution.

What is neutralisation?

Neutralisation is the reaction between an acid and a base to produce a salt and water only.

Write the general equation for neutralisation.

The general equation for neutralisation is: acid + base → salt + water.

What is the ionic equation for an acid-alkali reaction?

The ionic equation is H⁺(aq) + OH⁻(aq) → H₂O(l).

What are acidic oxides?

Acidic oxides are oxides of non-metals that react with bases to form a salt and water.

Give two examples of acidic oxides.

Examples of acidic oxides include SO₂ and CO₂.

What are basic oxides?

Basic oxides are oxides of metals that react with acids to form a salt and water.

Give two examples of basic oxides.

Examples of basic oxides include CuO and CaO.

What are amphoteric oxides?

Amphoteric oxides can react with both acids and bases to produce a salt and water.

Give two examples of amphoteric oxides.

Examples of amphoteric oxides include Al₂O₃ (aluminium oxide) and ZnO (zinc oxide).

What defines a soluble salt?

A salt is formed when the hydrogen in an acid is replaced by a metal or ammonium.

Describe Method 1 for preparing salts of reactive metals.

Method 1 involves titration, reacting an acid with an alkali, using an indicator to find the end-point, and then repeating without the indicator for a pure salt solution.

Describe Method 2 for preparing most salts.

Method 2 involves reacting an acid with an excess of an insoluble reactant (metal, base, or carbonate), then filtering out the excess solid, and evaporating water to form crystals.

What does hydrated mean?

Hydrated refers to a substance that is chemically combined with water, such as CuSO₄·5H₂O.

What does anhydrous mean?

Anhydrous refers to a substance that contains no water, such as CuSO₄.

How are insoluble salts prepared?

Insoluble salts are prepared by precipitation, mixing two soluble salt solutions to form an insoluble salt that precipitates.

Give an example of a reaction that forms an insoluble salt.

An example is: BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq).