Sec 3 Combined Science (Chemistry) Acids & Bases topical questions

Universal Indicator is added to three solutions: A turns red, B turns green, C turns violet. State whether each solution is acidic, neutral or alkaline.

Complete these word equations: (a) hydrochloric acid + zinc → (b) hydrochloric acid + calcium carbonate →

Name the salt formed in each reaction: (a) nitric acid + potassium hydroxide (b) hydrochloric acid + sodium hydroxide

Classify each oxide as acidic, basic, amphoteric or neutral: Na₂O, CO₂, Al₂O₃, CO.

Magnesium reacts with dilute hydrochloric acid, and calcium carbonate reacts with dilute hydrochloric acid. (a) Write the balanced equation, with state symbols, for the reaction of magnesium with hydrochloric acid. (b) Write the balanced equation, with state symbols, for the reaction of calcium carbonate with hydrochloric acid.

Explain neutralisation in terms of ions, and write the ionic equation for the reaction between any dilute acid and any aqueous alkali.

A farmer finds her paddy-field soil has a pH of 4.2, but the crop grows best near pH 6.5. (a) State what is wrong with the soil. (b) Name the chemical she should spread on the field. (c) Explain, in terms of ions, how the treatment works, and state one risk of using too much of it.

A student warms a mixture of calcium hydroxide and ammonium chloride in a test tube. (a) Write the balanced equation for the reaction. (b) Name the gas released and state the test that identifies it. (c) Explain why a gardener should not mix lime with an ammonium fertiliser before spreading them on a lawn.

A student slowly adds dilute hydrochloric acid to aqueous sodium hydroxide containing a few drops of Universal Indicator, starting with excess alkali. Describe and explain the colour changes observed, up to and beyond the point where the acid exactly neutralises the alkali.

A grey-white solid X is suspected of being zinc oxide. (a) Describe what you would observe when separate samples of X are added to dilute hydrochloric acid and to aqueous sodium hydroxide, if X is zinc oxide. (b) Write the balanced equation for each reaction. (c) State the term for this behaviour and name one other oxide that behaves in the same way.

A factory chimney releases sulfur dioxide, and the lake beneath it has slowly become too acidic for fish. (a) Explain how sulfur dioxide makes the water acidic. (b) Explain, with an ionic equation, why spreading finely divided calcium hydroxide around the lake shore can restore the water to a healthier pH. (c) State one environmental effect that untreated acidity of this kind has on buildings as well as lakes.

A student adds dilute hydrochloric acid to three unlabelled white powders, P, Q and R. Powder P fizzes and the gas turns limewater milky. Powder Q dissolves with no fizzing, and the solution warms slightly. Powder R dissolves but shows no other change. (a) Identify the type of compound in P, and write the equation for its reaction with hydrochloric acid if P is sodium carbonate. (b) State what type of compound Q is likely to be, write the ionic equation for the reaction that warms the solution, and explain why the temperature rises. (c) Suggest what R could be and explain, using the reaction patterns of acids from this chapter, why it shows no change.