Acids, bases and salts — IGCSE Sciences - Co-Ordinated (0654) questions by topic
Explaining why sodium and carbon form different types of oxide, tracking the rate of magnesium reacting with dilute hydrochloric acid, suggesting the pH of a dilute acid, and identifying a strong acid's pH value from a list are the demands behind the 5 acids, bases and salts questions from the 2023 papers, worth 9 to 13 marks.
State, describe and calculate are the leading command words, with identify and complete used where a value or missing word must be pinned down precisely. Practise the rate-of-reaction and pH questions here and submit each attempt for instant marking, so a mismatched pH value or a wrongly named salt product is caught before it undermines an otherwise sound explanation of the chemistry.
What examiners look for
- Examiners repeatedly found candidates unable to state that non-metals form acidic oxides while metals form basic oxides.
- A recurring criticism is that ionic and polymer were popular incorrect suggestions where a different bonding term was needed, and some candidates gave structures of a sodium ion and a chloride ion instead of what was asked.
- Many candidates found describing the reaction of lithium with water, and the trend in reactivity down the group, difficult.
- Few candidates could explain what the term exothermic actually means, and many did not state whether a factor increased or decreased.
- Strong answers, according to the reports, gave clear descriptions of the difference between a solid and a gas and successfully balanced the required equation, though many candidates missed that the salt produced should be named as magnesium sulfate.
October–November 2023, Paper 31
A student investigates the reaction between magnesium and dilute sulfuric acid. During the reaction, hydrogen gas and a salt are made. Complete the word equation for this…
Answer this question and get it marked →October–November 2023, Paper 33
Fig. 8.1 shows the apparatus a student uses to investigate the rate of reaction between magnesium and dilute hydrochloric acid. Hydrogen gas is collected in the measuring…
Answer this question and get it marked →Sodium forms a basic oxide. Carbon forms acidic oxides. State why they are different.
Answer this question and get it marked →October–November 2023, Paper 41
The pH of a solution describes how acidic or alkaline it is. State which of these values shows the pH of a strong acid. Tick one box. 14 / 7 / 5 / 1
Answer this question and get it marked →October–November 2023, Paper 43
An aqueous solution of dilute hydrochloric acid is acidic. Suggest the pH of an aqueous solution of dilute hydrochloric acid.
Answer this question and get it marked →Other IGCSE Sciences - Co-Ordinated topics
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