Test Yourself 8.2 – Chemistry Form 4 Chapter 8 (Manufactured Substances in Industry)

Question 1:
Silica is used to make all types of glass.
(a) State the type of glass that is made up of only silica.
(b) Soda-lime glass contains alkali metal ions. Name the ion.

Answer:
(a) Fused silica glass

(b) Sodium ion

Question 2:
A sample of borosilicate glass has composition of 80% silica, SiO₂, 15% boron oxide, B₂O₃ and 5% alumina, Al₂O₃. Calculate the mass of each component in the borosilicate glass sample with mass of 1 kg.

Answer:
$$\text { Mass of silica, } \begin{aligned} \mathrm{SiO}_2 & =\frac{80}{100} \times 1000 \mathrm{~g} \\ & =800 \mathrm{~g} \end{aligned}$$
$$\text { Mass of boron oxide, } \begin{aligned} \mathrm{B}_2 \mathrm{O}_3 & =\frac{15}{100} \times 1000 \mathrm{~g} \\ & =150 \mathrm{~g} \end{aligned}$$
$$\text { Mass of alumina, } \begin{aligned} \mathrm{Al}_2 \mathrm{O}_3 & =\frac{5}{100} \times 1000 \mathrm{~g} \\ & =50 \mathrm{~g} \end{aligned}$$

Question 3:
Aini’s mother : Aini, do not store food in lead crystal glass containers.
Aini: Why not, mother?

Based on the conversation above, explain the advantages and disadvantages of using containers made from lead crystal glass.

Answer:
Advantages:
• The transparent property enables the food in the container to be visible
• Can be easily cleaned and does not leave any traces
• High heat resistance

Disadvantages:
• Heavy because lead glass has high density
• Risk of lead poisoning, as lead can dissolve and diffuse into food