Acids and bases

Question 1

Half equivalence point

Answer 1

Only on weak acid strong base titrations

pH=pKa

Question 2

Weak acid weak base pH curve

Answer 2

No suitable indicator as no sharp end point

No equivalence point

Question 3

Strong acid weak base titration curve

Answer 3

3-6

Question 4

Weak acid strong base titration pH curve

Answer 4

8-10

Question 5

Strong acid strong base titration pH curve

Answer 5

3-10

Question 6

Features of a pH curve

Answer 6

show pH change
equivalence point moles of alkali=moles of acid
rapid change around equivalence point
end point is where indicator changes colour

Question 7

What is a pH meter and how to calibrate one

Answer 7

device able to determine pH of solution
1. rinse probe with deionised water and dry. Place in a pH 4 buffer solution
2. wait for reading to remain steady and set pH meter to 4
3. rinse deionised water and place in pH 10 buffer solution
4. wait for reading to remain steady and set pH meter to 10
5. graph of pH of buffer against pH measured (y axis)

Question 8

Concentration equation for strong acids

Answer 8

[HCl]=[H+]

[H2SO4]X2=[H+]

Question 9

Ka equation and when it is used

Answer 9

Ka=[H+][A-]/[HA]

buffers and weak acids

in buffers A- + HA can be mols

Question 10

Kw equation and what it is as 298K (room temperature) and when it is used

Answer 10

Kw=[H+][OH-]

[H2O] is taken to be constant as it is very high

1.00X10-14 mol2dm-6

strong bases and pure/neutral water

Question 11

Amphoteric meaning

Answer 11

A substance that can act as an acid and a base