2018 - JAMB Chemistry Past Questions and Answers - page 6

This is because the quick-lime acts as a drying agent hence, it can dry most gases except ammonia. Consequently, it removes the water vapour. Quick-lime (calcium oxide) reacts with the carbon dioxide forming calcium carbonate. Carbon dioxide and monoxide is eliminated leaving nitrogen, and the rare gases.

Oxygen is collected by the downward displacement of water because it is only slightly soluble in water and is less dense than water. It cannot be collected by downward displacement of air since oxygen will get mixed with other gases in air.

Answered here

A catalyst is a substance that speeds up a chemical reaction, but is not consumed by the reaction.

The setup could go like this:

A fire where the coal burns. A boiler full of water that the fire heats up to make steam. A cylinder and piston, rather like a bicycle pump but much bigger. Steam from the boiler is piped into the cylinder, causing the piston to move first one way then the other.

Ref.

2NaOH + H\(_2\) SO\(_4\)↔Na\(_2\)SO\(_4\) + 2H\(_2\)O

  V x 0.5M = 2(10 x 1.25)

  0.5V = 2 x 12.5

  0.5V = 25

  V = 250.5 = 50cm\(^2\)

From the dilution law:

  C\(_1\)V\(_1\) = C\(_2\)V\(_2\)

  C\(_1\) = Initial conc. of NaOH = 0.6M

  V\(_1\) = Initial Volume of NaOH = 300cm3

  C\(_2\) = Final conc. of NaOH = 0.4M

  V\(_2\) = Final Volume of NaOH = ?

  V\(_2\) = \(\frac{C_1V_1}{C_2}\)

  V\(_2\) = \(\frac{0.6 \times 300}{0.4}\)

  V\(_2\) = 450 cm\(^3\)

Diamond is a covalent macromolecule, and typical of a covalent substance is an insulator. All valence electrons are localized in well-defined covalent bonds and hence are not free to move through the structure