2022 - JAMB Chemistry Past Questions and Answers - page 3

Fractional distillation is a process used in crude oil refineries to separate (as well as join or split) the various lengths of hydrocarbon chains to create different petroleum products from the different distillates. More.

C  $\frac{69}{12}$   H  $\frac{15.3}{1}$     O  $\frac{30.7}{16}$

C = 5.75
H = 15.3
O = 1.92

C $\frac{5.75}{1,92}$    H  $\frac{15.3}{1.92}$     O  $\frac{1.92}{1.92}$

C${}_3$H${}_8$O

From the given equation, 2 mol H${}_2$ reacted with 1 mol of O${}_2$

50cm${}^3$ hydrogen reacted with 25cm${}^3$ oxygen

remainder oxygen = supplied amount - reacted amount 

=> 75cm${}^3$ - 25cm${}^3$

= 50cm${}^3$

NaH ionic hydride which is also known as saline (salt-like) hydride, composed of Na+ and H− ions

Charles' law states that the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature if the pressure remains constant.

Given that:
V${}_1$ = 29.5cm${}^3$
V${}_2$ = ?
T${}_1$ = 0ºc or 273k
T${}_2$ = 15ºc or 288k

$\frac{V_1}{T_1}$ = $\frac{V_2}{T_2}$

V${}_2$ = $\frac{V_{1}x{T}_2}{T_1}$ 

=> $\frac{29.5x288}{273}$

V${}_2$ = 31.1cm${}^3$

Enthalpy changes of neutralization are always negative - heat is released from the reaction of an acid and an alkali.

Such enthalpy changes are smaller in magnitude compared to that between the reaction of strong acids and strong bases.

Sulfur, due to the burning of coal in the process of generating electricity.

An alkene is produced when dehydration of alcohol is performed in which alcohol, upon reaction with protic acids, loses a molecule of water to form alkenes.

Such a reaction is an elimination reaction.

An endothermic reaction is a chemical reaction in which heat is absorbed from its environment hence resulting in an increase in the enthalpy H of the system.

Examples of solids in gas mixture:

• smoke
• ice clouds
• dust

Examples of liquid in gas mixture:

• fog
• mist
• vapour
• hair sprays

Examples of gas in solid mixture:

• aerogel
• styrofoam.