JAMB CBT Software 2024 - Free Download
JAMB CBT Mobile App 2024 - Free Download

2021 WAEC Chemistry Theory (a)i. State two characteristics of a homologous series. (ii) Explain briefly why there are differences in...

Chemistry
WAEC 2021

(a)i. State two characteristics of a homologous series.

(ii) Explain briefly why there are differences in the reaction of ethane and ethene.

(b) When crystals of sodium chloride were warmed with concentrated tetraoxosulphate( VI) acid, a gas was evolved.
(i) Name the gas.
(ii) State two physical properties of the gas.
(iii) Write a balanced chemical equation for the reaction.

(c)i. What are hydrocarbons?
(ii) State two natural sources of hydrocarbons.
(iii) A hydrocarbon contains 83% of carbon by mass. Calculate its empirical formula. [H=1.0, C=12.0]

(d) Draw and label a diagram of a set-up that could be used to electroplate a copper ornament with silver

JAMB CBT Mobile App 2024 - Free Download
JAMB CBT Software 2024 - Free Download
JAMB CBT 2024 - Candidates, Schools, Centres, Resellers - Get Ready!
JAMB 2024 Whatsapp Group - Join us here
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
Explanation

(a)i. Characteristics of homologouS series

- All members can be represented by a general formula.
- Each member of the series differs from the next by a constant/fixed number of atoms
- CH\(_{2}\)/ 14 amu
- All members of the series show a gradual change in physical properties such as density.
- AII members have similar chemical properties/same functional groups.
- All members of the group are prepared using a similar chemical method

(ii) Differences in the Reaction of Ethane and Ethene

- Ethane is a saturated hydrocarbon containing a single bond and therefore undergoes mainly substitution reaction while ethene is an unsaturated hydrocarbon containing a double bond and hence undergoes an addition reaction

(b)i. The gas is hydrogen chloride.

(ii) Physical properties of the gas:
- Colourless
- Has choking smell
- Denser than air
- Gas is soluble in water.
- Gas fumes in moist air.

(iii) Write a balanced equation reaction:

2HaCl\(_{(s)}\) + H,SO\(_{4(aq)}\), \(\implies\) Na2SO\(_{4(aq)}\) + 2HC\(_{(g)}\) OR HaCI\(_{(s)}\) + H\(_{2}\)SO\(_{4(aq)}\) \(\implies\) NaHSO\(_{4(aq)}\) + HCl\(_{(g)}\)

(c)i. Hydrocarbons are compounds containing only hydrogen and carbon

(ii) Two Natural Sources of Hydrocarbons:
- Coal
- Petroleum/crude oil Natural gas.

(iii) A hydrocarbon contains 83.0 % of carbon by mass. calculate its emprical formular (H =1.0; C = 12.0).

Solution: C = 83.0 %.

\(\therefore\) % H\(_{2}\) = 100 - 83 17%

(d) Draw and label a diagram of a set-up that could be used to electroplate a copper ornament with silver. 

Open photo

 

 


Report an Error Ask A Question Download App
JAMB CBT Mobile App 2024 - Free Download
JAMB CBT 2024 - Candidates, Schools, Centres, Resellers - Get Ready!
JAMB CBT Software 2024 - Free Download
JAMB 2024 Whatsapp Group - Join us here
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995

Contributions ({{ comment_count }})

Please wait...

{{ settings.no_comment_msg ? settings.no_comment_msg : 'There are no comments' }}

Quick Questions

Post your Contribution

Please don't post or ask to join a "Group" or "Whatsapp Group" as a comment. It will be deleted. To join or start a group, please click here

{{ quote.posted_by.display_name }}
{{ settings.form_textarea_description }}
 
JAMB 2024 Whatsapp Group - Join us here
JAMB CBT 2024 - Candidates, Schools, Centres, Resellers - Get Ready!
JAMB CBT Software 2024 - Free Download
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
JAMB CBT Mobile App 2024 - Free Download
JAMB CBT 2024 - Candidates, Schools, Centres, Resellers - Get Ready!
JAMB CBT Software 2024 - Free Download
JAMB 2024 Whatsapp Group - Join us here
JAMB CBT Mobile App 2024 - Free Download