Acid & Bases

Question 1

What is a Bronsted Lowry Acid?

Answer 1

A substance that can donate a proton

Question 2

What is a Bronsted Lowry Base?

Answer 2

A substance that can accept a proton

Question 3

What is the formula to calculate pH?

Answer 3

pH = -log [H+]

Question 4

What is the formula to calculate H+ using pH?

Answer 4

H+ = 1 x 10*-pH

Question 5

What formula must you use when calculating Dilutions?

Answer 5

C1 x V1 (old) = C1 X V2 (new)

Question 6

What is the formula for the ionic product of water, Kw?

Answer 6

Kw = [H+] [OH-] or Kw = [H+]*2

Question 7

What is the value of Kw?

Answer 7

1 x 10*-14

Question 8

How do you calculate the pH when mixing a strong acid with a strong base?

Answer 8

• Calculate Moles of Acid
• Calculate Moles of Base
• Work out No of Moles of Acid/Base in excess
• Work out new concentration of [H+] / [OH-]
• Work out pH using relevant formula

Question 9

What is the formula used when finding pH of weak acids?

Answer 9

Ka = [H+]*2 / [HA]

Question 10

Why is the Ka constant used for weak acids?

Answer 10

This is because weak acids don’t fully dissociate into their ions

Question 11

How do you calculate pKa?

Answer 11

pKa = -log10 (Ka)

Question 12

How do you calculate Ka using pKa?

Answer 12

Ka = 10*-pKa

Question 13

How do you calculate pH when mixing a weak acid with a strong base?

Answer 13

• Calculate moles of HA
• Calculate moles of OH-
• Calculate moles of excess HA or OH-
• If HA excess, Use Ka
• If OH- excess, Use Kw