C8 - Acids, bases and salts Flashcards
Describe acid, alkali and neutral on the pH scale [3]
Acid pH 1-6 / Alkali pH 8-14 / Neutral pH 7
Describe the effect of acid and alkali on blue litmus [2]
Acid turns blue litmus red / Alkali results in no change to blue litmus
Describe the effect of acid and alkali on red litmus [2]
Acid results in no change to red litmus / Alkali turns red litmus blue
Define an acid [1]
A proton donor
Define a base [1]
A proton acceptor
What is an alkali? [1]
A soluble base
What is a strong acid? [1] Give an example [1]
An acid that completely dissolves in solution - an example is hydrochloric acid
What is a weak acid? [1] Give an example [1]
An acid that partially dissolves in solution - an example is ethanoic acid
Write a symbol equation for the reaction between magnesium and hydrochloric acid [1]
Mg (s) + 2HCl (aq) → MgCl₂ (aq) + H₂ (g)
Write a symbol equation for the reaction between magnesium oxide and hydrochloric acid [1]
MgO (s) + 2HCl (aq) → MgCl₂ (aq) + H₂O (l)
Write a symbol equation for the reaction between magnesium hydroxide and hydrochloric acid [1]
Mg(OH)₂ (aq) + 2HCl (aq) → MgCl₂ (aq) + 2H₂O (l)
Write a symbol equation for the reaction between magnesium carbonate and hydrochloric acid [1]
MgCO₃ (s) + 2HCl (aq) → MgCl₂ (aq) + H₂O (l) + CO₂ (g)
Write a symbol equation for the reaction between calcium hydroxide and ammonium chloride [1]
Ca(OH)₂ (s) + 2NH₄Cl (aq) → CaCl₂ (aq) + H₂O (l) + 2NH₃ (g)
Define neutralisation with an ionic equation [2]
A reaction between an acid and a base to produce water / H⁺ + OH⁻ → H₂O
Describe the difference between non-metal oxides and metal oxides with examples [2]
Non-metal oxides (e.g. CO₂) are acidic and dissolve in water to produce H⁺ ions / Metal oxides (e.g. CuO) are basic and if they are solube will produce OH⁻ ions
What are amphoteric oxides? Give two examples [3]
Oxides that react with both acids and alkalis to produce salts (e.g. ZnO and Al₂O₃)
Test and positive result for carbonate anion CO₃²⁻ [2]
Add dilute acid / effervesence CO₂ produced
Test and positive result for chloride anion Cl⁻ [2]
Acidify with dilute nitric acid and add aqueous silver nitrate / white precipitate
Test and positive result for bromide anion Br⁻ [2]
Acidify with dilute nitric acid and add aqueous silver nitrate / cream precipitate
Test and positive result for nitrate anion NO₃⁻ [2]
Add aqueous sodium hydroxide, then aluminium foil and warm / ammonia produced
Test and positive result for sulphate anion SO₄²⁻ [2]
Acidify, then add aqueous barium nitrate / white precipitate
Ammonium cation NH₄⁺ - effect of aqueous sodium hydroxide / effect of aqueous ammonia [2]
Ammonia produced on warming / no effect
Calcium cation Ca²⁺ - effect of aqueous sodium hydroxide / effect of aqueous ammonia [2]
White precipitate which is insoluble in excess / no precipitate or very slight white precipitate
Copper(II) cation Cu²⁺ - effect of aqueous sodium hydroxide / effect of aqueous ammonia [2]
Light blue precipitate which is insoluble in excess / light blue precipitate which is soluble in excess giving a dark blue solution
Test and positive result for iron(II) cation Fe²⁺ - effect of aqueous sodium hydroxide [2] / effect of aqueous ammonia [2]
Green precipitate which is insoluble in excess / green precipitate which is insoluble in excess
Iron(III) cation Fe³⁺ - effect of aqueous sodium hydroxide / effect of aqueous ammonia [2]
red-brown precipitate which is insoluble in excess / red-brown precipitate which is insoluble in excess
Zinc cation Zn²⁺ - effect of aqueous sodium hydroxide / effect of aqueous ammonia [2]
White precipitate which is soluble in excess giving a colourless solution / white precipitate which is soluble in excess giving a colourless solution.
Test and positive result for NH₃ gas [1]
Turns damp red litmus paper blue
Test and positive result for CO₂ gas [1]
Turns limewater milky
Test and positive result for Cl₂ gas [1]
Bleaches damp litmus paper
Test and positive result for H₂ gas [1]
‘pops’ with a lighted splint
Test and positive result for O₂ gas [1]
Relights a glowing splint
Flame test colour for lithium metal ion [1]
Red
Flame test colour for sodium metal ion [1]
Yellow
Flame test colour for potassium metal ion [1]
Lilac
Flame test colour for copper metal ion [1]
Blue-green
