Bronsted-Lowry acids and bases

Question 1

What is the simple definition of an acid?

Answer 1

Acids dissociate and release H+ ions in aqueous solution.

Question 2

What is the simple definition of a base?

Answer 2

Bases dissociate and release OH- ions in aqueous solution.

Question 3

What can we also say about alkalis?

Answer 3

They are insoluble bases.

Question 4

What is the definition of a Bronsted-Lowry acid?

Answer 4

A proton donor.

Question 5

What is the definition of a Bronsted-Lowry base?

Answer 5

A proton acceptor.

Question 6

What is the equation for how weak acids dissociate?

Answer 6

CH3COOH = CH3COO- + H+.
= is the equilibrium sign.

Question 7

What is the equation for how strong acids dissociate?

Answer 7

HCl - H+ + Cl-.

Question 8

What does a conjugate acid-base pair contain?

Answer 8

It contains two species that can be interconverted by transfer of a proton.

Question 9

What is an example of a conjugate acid-base pair?

Answer 9

HCl (aq) and Cl- (aq):
- In the forward direction, HCl releases a proton to form its conjugate base, Cl-.
- In the reverse direction, Cl- accepts a proton to form its conjugate acid, HCl.

Question 10

What are 3 examples of conjugate acid-base pairs?

Answer 10

1. Nitric acid: HNO3 (aq) = H+ (aq) + NO3- (aq).
2. Sulfuric acid: H2SO4 (aq) = H+ (aq) + HSO4- (aq).
3. Ethanoic acid: CH3COOH (aq) = H+ (aq) + CH3COO- (aq).

Question 11

How can you describe the two conjugate acid-base pair of HCl + OH- = H2O + Cl-? Forward and reverse?

Answer 11

1. In the forward reaction:
   - HCl is an acid as it donates H+ - acid 1.
   - OH- is a base as it accepts H+ - base 2.
2. In the reverse reaction:
   - H2O is an acid as it donates H+ - acid 2.
   - Cl- is a base as it accepts H+ - base 1.

Question 12

How can you describe the two conjugate acid-base pair of HCl + H2- = H3O++ Cl-? Forward and reverse?

Answer 12

1. In the forward reaction:
   - HCl is an acid as it donates H+ - acid 1.
   - H20 is a base as it accepts H+ - base 2.
2. In the reverse reaction:
   - H30+is an acid as it donates H+ - acid 2 (conjugate).
   - Cl- is a base as it accepts H+ - base 1.

Question 13

What do the terms monobasic, dibasic, and tribasic mean?

Answer 13

Refer to the total number of H+ ions in the acid that can be replaced per molecule in an acid-base reaction (replacement of protons by metal ions or ammonium ions to form a salt).

Question 14

What is an example of a monobasic acid? (2)?

Answer 14

HCl/CH3COOH.

Question 15

What is an example of a dibasic acid?

Answer 15

H2CO3

Question 16

What is an example of a tribasic acid?

Answer 16

H3BO3.

Question 17

How do you write complete neutralisation equations?

Answer 17

1. Need to look at where the acid is monobasic, dibasic, or tribasic.
2. Balance the NaOH with the amount of hydrogen atoms in the acid:
   - e.g. HNO3 is monobasic so only needs one sodium.
   HNO3 + NaOH - NaNO3 + H2O.
   OR
   - H2SO4 has two replaceable H+ ions.
   H2SO4 + 2NaOH - Na2SO4 + 2H2O.

Question 18

What is the ionic reaction of HCl with H+ ions?

Answer 18

1. 2HCl + Mg - MgCl2 + H2
2. 2H+ + 2Cl- + Mg - Mg2+ + 2Cl- + H2 (cancel the spectator ions.
3. 2H+ + Mg - Mg2+ + H2.

Question 19

What are spectator ions?

Answer 19

Ions that do not change during the reaction.

Question 20

What reactions do diluted acids take part in?

Answer 20

Acid + metal - salt + hydrogen

Question 21

What is the equation for neutralisation of acids with carbonates?

Answer 21

Acid + carbonate - salt + water + carbon dioxide:
- you can cancel spectator ions in the equations.

Question 22

What is the neutralisation equation with metal oxides?

Answer 22

Acid + base - salt + water.

Question 23

What is the neutralisation equation of acids with alkalis?

Answer 23

Acid + alkali - salt + water:
- H+ + OH- - H2O

Question 24

When writing neutralisation reactions what do you need to keep in the equation?

Answer 24

The charges of the metals/H+.