Module 3: Reactive Chemistry

Question 1

Difference between chemical and physical change

Answer 1

Chemical: Formation of a new substance, are not reversible caused by the breaking and forming of chemical bonds
Physical: No formation of a new substance involved change in state/shape

Question 2

List indicators of chemical changes

Answer 2

• Change in temp
• Change in colour
• Odour
• Precipitate
• Bubbles (gas)

Question 3

List an example of bubble/gas evolution

Answer 3

Marble chips added in hydrochloric acid, marbles dissolve and bubbles of colourless gas form on bubble surface

Question 4

What is a precipitate reaction

Answer 4

When 2 aqueous solutions combine to produce an insoluble salt

Question 5

Define a combustion reaction

Answer 5

When a hydrocarbon reacts with oxygen gas to produce carbon dioxide and water. Releasing energy in the form of heat and light therefore an exothermic reaction

Question 6

What a oxidising agent

Answer 6

the oxidising agent causes another substance to be oxidised, meaning the other substance loses electrons. At the same time, the oxidising agent itself is reduced and gains those electrons.

Question 7

What is a reductant

Answer 7

the reducing agent

Question 8

What methods did the Indigenous use to detoxify their food

Answer 8

1. Pounding and grinding plant fibres followed by soaking and washing to leach out toxins from the fibres
2. Roasting in a fire to decompose toxins
3. Fermentation of seed kernels