1.12 Acids And Bases

Question 1

What is the definition of an acid?

Answer 1

Proton donor

Question 2

What is the definition of a base?

Answer 2

Proton acceptor

Question 3

What is the definition of conjugate base?

Answer 3

Accepts a H+ to reform original acid

Question 4

How is a conjugate acid formed?

Answer 4

When base accepts a proton

Question 5

Definition of a strong acid?

Answer 5

Proton fully dissociates

Question 6

What are the two chemical tests to distinguish between strong and weak acids?

Answer 6

Universal Indicator- Strong acids= lower pH
Titration- Weaker acids will require less alkali to neutralise

Question 7

What is the definition of pH?

Answer 7

pH=-log[H+]

Question 8

How to calculate concentration from pH?

Answer 8

10^-pH

Question 9

What is the equation for the dissociation of water?

Answer 9

H2O>< H+ + OH-

Question 10

What is the expression for Kw?

Answer 10

Kw= [H+][OH-] Or Kw= [H+]^2

Question 11

What happens to Kw of pure water as temperature increases?

Answer 11

• Kw becomes disproportional
• More H+ ions dissociate
• Kw Increases

Question 12

Why is water at whatever pH still neutral?

Answer 12

Because OH- and H+ ions are equal

Question 13

What is the definition of a buffer?

Answer 13

A solution which resists a small change of acid or alkali to maintain pH

Question 14

What is the definition of pKa?

Answer 14

-log(Ka)

Question 15

What indicator is suitable for a strong acid weak base reaction?

Answer 15

Methyl orange

Question 16

Which indicator is suitable for weak acid strong base reaction and why?

Answer 16

• Phenolphthalein
• End point of phenolphthalein is within vertical point of graph so colour will change as equillibrium of H+ ions and OH- ions shift

Question 17

Why does the ph of pure water change with temperature?

Answer 17

• Ionisation of water is endothermic
• When temp increases equilibrium shifts to right increasing concentration of ions