Brønsted lowry

Question 1

What is a B-L Acid

Answer 1

A proton donor (the H+ must have a slight +)

Question 2

What is a BL Base

Answer 2

A proton acceptor, must have a lone pair that can be used to form a dative covalent bond with proton

Question 3

What is a conjugate base pair?

Answer 3

An Acid is a base with a hydrogen attached a Base is an acid with the hydrogen removed.

Question 4

Is water an acid or a base?

Answer 4

Both! Water can be an acid donating H+ to form OH-, or it can be a base accepting H+ to form H3O+!

Question 5

How do we show complete dissociation from partial dissociation

Answer 5

Complete as a single arrow

Partial has a reversible one

Question 6

What is the difference between strong acids and weak acids?

Answer 6

Strong fully dissociate where weak only partially dissociates.

Question 7

Examples of strong Acids?

Answer 7

HCl, HNO3, H2SO4 etc (inorganic)

Question 8

Example of weak?

Answer 8

Organic

Question 9

What is the formula for ph?

Answer 9

Ph= -log[H+]

Question 10

How do we calculate mol H+ when we know the conc of a strong acid?

Answer 10

Monoprotic! So 1mol/dm3 = 1 mol H+ per dm3

Question 11

What does Ka tell us?

Answer 11

Large Ka = large dissociation .^. Strong acid

Lil Ka = lil dissociation .^. Weak acid

Question 12

What is Ka for weak acids?

Answer 12

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

Question 13

What is Kw?

Answer 13

Dissociation of water has a set value at set temp.

Question 14

How do we work our ph of strong base?

Answer 14

Use Kw! Will be given in the question!
Kw= [H+] x [OH-]
As strong base dissociates fully, [OH-] we know
[H+]= Kw / [OH-]
The use Ph formula

Question 15

How do we compare strength?

Answer 15

Use eqimolar samples at same Temp. And measure ph.
Titrations Acid and base, if acid and base have similar Ka/Kp etc then resulting salt will be neutral but weak acid strong base or strong base weak acid then ph will shift.

Question 16

How do we determine Ka?

Answer 16

Make up a standard solution
Use calibrated ph meter to read
Calc mol Acid and conc
Use ph to calc H+
Calc Ka

Question 17

What is the equivalence point?

Answer 17

When the acid and base have reacted together in exactly the same amounts according to the stoichiometric equation. The ph at this point depends on the comb of acid and base used.

Question 18

Sources of error in experiments

Answer 18

Assuming HA i = HA eq
Transfer errors in weighing and dissolving
Ph measurement!

Question 19

What happens to an indicator when [H+] is increased?

Answer 19

Equil. Goes left and conc HIn goes up

Question 20

What happens when we increase [OH-]?

Answer 20

Equil goes Right, as H+ decreases H2O formed and so less HIn formed.

Question 21

How do we work out when the transition colour will be seen?

Answer 21

KIn! =[H+] [In-] / [HIn]
When [HIn] = [In-] KIn .^. = [H+]
And then work our Ph!

Question 22

What is a buffer?

Answer 22

A solution of a constant Ph that is resistant to ph changes.

Question 23

How do buffers work?

Answer 23

They contain a weak acid which only partially dissociates in water producing a large conc. of conjugate acid and a small conc of conjugate base. To this we add conjugate base salt that fully dissociates in water. This produces a pot of conjugate acid and one of conjugate base which allows the solution to react to small additions of acids and bases.

Question 24

How do we calc the ph of a buffer?

Answer 24

From Ka calc we make [H+] the subject
Only a small amount of HA dissociates therefore [Ha] In =[HA] eq
The salt is ionic so fully dissociates
Then work out ph
[H+] = ka x [acid]/ [base]