Final exam notes

Western Cape Education Department




PHYSICAL SCIENCES


Grade 12: June 2025



ACIDS & BASES TUTOR GUIDE



SPRING SCHOOL




1
Grade 12 Spring School Tutoring Programme: Physical Sciences

, ACIDS & BASES – Pre Test
QUESTION 1 (MULTIPLE-CHOICE)


1.1 C 

1.2 B 

1.3 C 

[6]


LONGER EXAM QUESTIONS ANSWERS

QUESTION 2
2.1
2.1.1 𝑝𝐻 = −log [𝐻3 𝑂+ ] (3)
4,2 = −log [𝐻3 𝑂+ ]
[𝐻3 𝑂+ ] = 6,31 𝑥 10−5 mol.dm-3 


2.1.2 WEAKER THAN (2)
• H2CO3 has a smaller Ka value than H2SO4, indicating that it ionises in-
completely.
OR
• H2CO3 has a pH of 4,2. Sulphuric acid has a lower pH.
OR
• H2CO3 has a concentration of 0,02 mol.dm-3, but [H3O+] is calculated
at 6,31 x 10-5 mol.dm-3. Therefore carbonic acid ionises incompletely
and is weaker than sulphuric acid that will ionise completely.
(ACCEPT ANY ONE )

SWAKKER AS
• H2CO3 het ‘n laer Ka waarde as H2SO4 wat aandui dat dit onvolledig
ioniseer.
OF
• H2CO3 het ‘n pH van 4,2. Swawelsuur het ‘n laer pH.
OF
• H2CO3 het ‘n konsentrasie van 0,02 mol.dm-3, maar [H3O+] is bereken as
6,31 x 10-5 mol.dm-3. Dus het koolsuur onvolledig ge-ioniseer en is swak-
ker as swawelsuur wat wel volledig ioniseer.




Grade 12 Spring School Tutoring Programme: Physical Sciences 2