Oceans 2: Acids & Bases

Question 1

Definition of acid

Answer 1

Proton / H+ donor

Question 2

Definition of base

Answer 2

Proton / H+ acceptor

Question 3

Why is H+ a proton

Answer 3

• H - proton = 1, electron =1, neutron =0

* H+ -proton = 1, electron=0, neutron = 0

Question 4

Definition of acid base reaction

Answer 4

Reaction involving the transfer of a proton

Question 5

I’m the equation below identify the acid and base and give reasoning

HNO3 + NH3 —> NH4+ + NO3-

Answer 5

• HNO3 = acid = donates H+

* NH3 = base = accepts H+

Question 6

What happens when acids / bases are added to water

Give 2 equations

Answer 6

Conjugate base pairs form in an equilibrium reaction ( both forward and reverse reaction can take place )

• Acid - HA
= HA + H2O H3O+ +A-

•Base - B
= B + H2O BH+ +OH-

Question 7

Definition of conjugate base pair

Show example using pairs from this equation:

HCl + H20 H3O+ + Cl-

Answer 7

Acid and base of a conjugate pair can be linked by an H+

• HCl H+ + Cl-
• H+ + H2O H3O+

Question 8

Identify the acid base pairs in the reaction below:

HCl + H20 H3O+ + Cl-

Answer 8

• Pair 1
= HCl ( acid ) and Cl- (base)

•Pair 2
= H2O ( base ) and H3O+ ( acid )

Question 9

What does pH stand for in simple terms

Answer 9

pH = power of hydrogen

Question 10

Definition of monoprotic acid

Give examples

Answer 10

• acid that releases 1 H+ ion per molecule

Eg. HCl, HNO3 ( nitric acid ), CH3 COOH ( ethanoic acid )

Question 11

Definition of diprotic acid

Give examples

Answer 11

• acid that releases 2 H+ ions per molecule

Eg. H2 SO4 ( sulphuric acid ) , H2 C2 O4 ( ethenedioic acid )

Question 12

Give the properties of strong acids

Answer 12

• completely dissociate ( ionise )

Question 13

Definition of dissociate

Answer 13

• completely break up into ions

Eg. Strong acids

= HA(aq) —> H+(aq) + A-(aq)

= concentration of all parts in the equation are the same

Question 14

Difference between STRONG acid & WEAK acid ( explain using formulas as well )

Answer 14

• STONG acid completely dissociates ( breaks apart to form ions )

Eg. HA —> H+ + A- ( all components have equal conc )

• WEAK acid does NOT completely dissociate ( only a small fraction of molecules break apart to form ions )

Eg. HA <=> H+ + A- ( in equilibrium )

Question 15

Give 3 common examples of STRONG acids

Answer 15

1. HCl = hydrochloric acid
2. HNO3 = nitric acid
3. H2 SO4 = sulphuric acid

Question 16

Give a common example of a WEAK acid

Answer 16

• carboxylic acids

Eg. Ethanoic acid

Question 17

Give 3 common examples of STONG bases

Answer 17

1. NaOH = sodium hydroxide
2. KOH = potassium hydroxide
3. Ba(OH)2 = barium hydroxide

Question 18

Give a common example of a WEAK base

Answer 18

NH3 = ammonia

Question 19

Give equation of reaction of weak acid and strong base

Answer 19

HA + OH- —> A- + H2O

acid + base —> salt + water

Question 20

Describe reaction of weak acid and strong base in terms of moles

Answer 20

For every mole of OH- added, 1 mole of HA is used up and 1 mole of A- is formed

Question 21

When the flowing weak acid reacts with a strong base calculated moles of:

1. HA left after
2. OH- left
3. A- made

When before =
• 4 moles of HA reacts within 2.5 moles of NaOH

Answer 21

1. HA = 1.5 left ( 4-2.5 )
2. OH- = 0 left ( because more HA than OH- )
3. A- = 2.5 made ( equivalent to whatever used up fully )