ACIDS & BASES

Question 1

What is the Bronsted-Lowry definition of acids and bases?

Answer 1

Acids- Proton donor

Bases- Proton acceptor

Question 2

What is the trend in electronegativity across a periodic table?

Answer 2

Increases as you go across a period and as you go down a group.

Question 3

What it a conjugate acid-base pair?

Answer 3

The species formed when an acid gives up a proton and can behave as a base.

When a base accepts a proton and can behave as an acid.

Question 4

When is a conjugate base bad at accepting protons?

Answer 4

When the conjugate acid is better at losing protons.

Question 5

When is a conjugate acid bad at losing protons?

Answer 5

When the conjugate base is better at accepting protons.

Question 6

What is the definition of amphoteric?

Answer 6

A species that can acts as both acid and base

Question 7

What is the rule regarding conjugates in acid-base reactions

Answer 7

Acids react with bases to give the conjugate base of the reactant acid.
The conjugate acid of the reactant base

Acid 1 + Base 2= Base 1 + Acid 2

Question 8

What does an acid-base reaction in aqueous solution reveal?

Answer 8

Whether the reactant acid or the conjugate acid is strongest.

Question 9

How can the concentration of hydrogen ions [H+] be deduced using the ionic product of water?

Answer 9

[H+]=Kw/[OH-]

Question 10

What is the definition of a strong acid?

Answer 10

Dissociated completely in water to give H3O+ and the conjugate base (A-)

Question 11

What is the definition of a weak acid?

Answer 11

Partially dissociates to give H3O+ and the conjugate base (A-)

Question 12

What is Ka?

Answer 12

The acid dissociation constant

Question 13

What does a larger Ka value indicate?

Answer 13

The greater degree to which the acid dissociates into its ions and the stronger acid

Question 14

What happens to extent of acid dissociation in a more dilute solution? Why?

Answer 14

Increases. Equilibrium will shift to the right to oppose the change in the increase of water.

Question 15

When should the [H+] due to the autoionisation of water not be ignored?

Answer 15

If the concentration of the solution is below 1x10-6

Question 16

What is a polybasic acid?

Answer 16

Acids which are capable of losing more than 1 proton

Question 17

What is a strong base?

Answer 17

one which fully dissociates into its ions in water

Question 18

What is a buffer?

Answer 18

It is a solution which can resist changes in pH on addition of small quantities of acid or alkali or on dilution.

Question 19

What is the ideal mixture of a buffer solution?

Answer 19

A mixture of a weak acid and its conjugate base.

Question 20

What are the steps to calculating the pH of a strong base?

Answer 20

1. Find out the conc of the solution
2. Conc of strong base = [OH-]
3. Use [H+]=[Kw]/[OH-]

Question 21

What are the steps to calculating the pH of a weak acid?

Answer 21

1. Identify the Ka of the acid
2. Use Ka formula = [H+]^2/[HA]
3. Rearrange formula
4. [H}=/Ka{HA}

Question 22

How to calculate the Ka of a weak acid?

Answer 22

1. Identify the pH of the acid
2. Inverse log the pH
3. Use Ka formula (don’t forget to square [H+]!)
4. Substitute the initial conc for [HA]

Question 23

If given the pH how is the molarity calculated in a strong acid?

Answer 23

Change pH to a negative, then inverse log

Question 24

Write an expression for pKa in terms of Ka

Answer 24

pKa= -log10Ka

Question 25

How do you calculate dilution factors?

Answer 25

Ca x Va = Cb x Vb