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Acids, Bases and Salts

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are oxides classified, and what is happening at the particle level during neutralisation?

Classify oxides as acidic, basic, amphoteric or neutral, and describe neutralisation as the reaction of hydrogen ions with hydroxide ions to form water
A focused answer to the O-Level Chemistry outcome on oxides and neutralisation. Classifying oxides as acidic, basic, amphoteric or neutral, and the ionic picture of neutralisation as hydrogen ions reacting with hydroxide ions to form water.
8 min answer →

How do chemists choose the right method to prepare a pure, dry sample of a particular salt?

Describe the preparation of soluble and insoluble salts, use solubility rules to choose the method, and carry out crystallisation and precipitation to obtain a pure salt
A focused answer to the O-Level Chemistry outcome on preparing salts. Choosing between the acid-plus-excess-solid, titration and precipitation methods using solubility rules, and obtaining a pure dry salt by crystallisation or filtration.
9 min answer →

What defines an acid and a base, and what are their characteristic reactions?

Describe acids as sources of hydrogen ions and bases as proton acceptors, distinguish strong and weak acids, and describe the characteristic reactions of acids with metals, carbonates and bases
A focused answer to the O-Level Chemistry outcome on acids and bases. Acids as sources of hydrogen ions, the difference between strong and weak acids, alkalis as soluble bases, and the three characteristic reactions of acids.
8 min answer →

How does the pH scale measure acidity, and how do indicators reveal it?

Describe the pH scale as a measure of acidity and alkalinity, relate pH to hydrogen ion concentration, and use indicators and universal indicator to determine pH
A focused answer to the O-Level Chemistry outcome on pH and indicators. The pH scale from 0 to 14, how pH relates to hydrogen ion concentration, the colours of common indicators, and using universal indicator to find pH.
8 min answer →