Chemistry: Reactivity, Extraction, and Acid Reactions

What happens to reactivity as the number of electron shells increases and why?

Reactivity increases due to greater distance from the nucleus, leading to a weaker attraction and a higher tendency to lose electrons.

metal and acid reaction (neutralisation)?

Metal + acid → salt + hydrogen.

What is an ore?

A rock containing enough metal to be economically worth extracting.

What are some disadvantages of extracting metals from the ground?

Destruction of habitat, noise and dust pollution, and large amounts of waste.

What is bioleaching?

A process that uses bacteria to leach metals from ore, producing a leachate solution.

What is the method of bioleaching?

Bacteria are used in channels to leach metal ions, producing a leachate solution from which metals are extracted.

What is phytomining?

A method that uses plants to extract metals from contaminated ground.

What are the steps involved in phytomining?

1. Plant growth to uptake metal ions. 2. Cut down and burn plants. 3. Dissolve ash to create a metal compound solution. 4. Extract metals by displacement or electrolysis.

What are the pros and cons of bioleaching?

Pros: environmentally friendly. Cons: very slow process and potential toxic runoff.

What is a displacement reaction?

An exothermic reaction where a more reactive metal displaces a less reactive metal from its compound.

What defines a strong acid?

An acid that fully dissociates in solution, breaking all bonds (e.g., HCl).

What defines a weak acid?

An acid that only partially dissociates in solution, maintaining some bonds (e.g., vinegar).

What is the difference between acid strength and acid concentration?

Strength refers to how many acid particles dissociate to release H+ ions, while concentration refers to the mass of acid particles dissolved in a given volume.

How does the pH scale relate to H+ ion concentration?

Each pH drop represents a tenfold increase in H+ ion concentration.

What is the function of a universal indicator?

It classifies substances as acidic, alkali, or neutral and shows pH through color changes.

What is the neutralisation reaction between an acid and an alkali?

Acid + alkali → salt + water (H+ + OH− → H2O).

What are the chemical symbols for sulfuric acid, nitric acid, and hydrochloric acid?

Sulfuric acid: H2SO4, Nitric acid: HNO3, Hydrochloric acid: HCl.

What is the independent variable in a titration practical?

The concentration of sodium hydroxide.

What is the method for conducting a titration?

Measure NaOH, add indicator, titrate against HCl until color change, and repeat for accuracy.

What is the reaction of a metal oxide with an acid?

Metal oxide + acid → salt + water.

What is the reaction of a metal carbonate with an acid?

Metal carbonate + acid → salt + carbon dioxide + water.

What is limewater used for?

To test for the presence of carbon dioxide.