Inorganic chemistry

Question 1

What is a positively charged ion known as?

Answer 1

Cations

Question 2

What is a negatively charged ion known as?

Answer 2

Anions

Question 3

What are zwitterions?

Answer 3

Both anions and cations – cations at low pH and anion at high pH

Question 4

What does the Bronsted-Lowry theory state?

Answer 4

An acid is a proton donor
A base is a proton acceptor

Question 5

What do monovalent, divalent, trivalent mean in terms of cations?

Answer 5

They have 1, 2 and 3 electrons to lose, respectively

Question 6

What is a proton?

Answer 6

Hydrogen ion – lost electron (H+)

Question 7

What happens when vinegar is put into water?

Answer 7

Proportion of hydrogen ions will dissociate = acetate and NH+

– Reversible action
– Acetate is now base
–Acetic acid is an acid

Question 8

What is true of bases?

Answer 8

Any base (HB+) can dissociate into hydrogen ions and conjugate base (reversible)

Question 9

What is pH?

Answer 9

Measure of the concentration of protons in solution

Question 10

What does more protons mean in terms of pH?

Answer 10

+ protons = lower pH

Question 11

What do less protons mean in terms of pH?

Answer 11

less protons = higher pH

Question 12

What is the equation for pH?

Answer 12

pH = log10 1/[H+] = -log10[H+]

Question 13

What is the pH of pure water?

Answer 13

7

Question 14

What is an example of a strong acid?

Answer 14

In aqueous solution, HCl is almost completely dissociated

–1M solution has a pH of 0

Question 15

What is an example of a weak acid?

Answer 15

In aqueous solution, HCl is ~0.4% dissociated and is thus a weak acid

–1M solution (vinegar) has pH of ~2.5

Question 16

How is acid strength measured?

Answer 16

Measured according to the pKa of the acid

Question 17

What is the pKa of the acid?

Answer 17

The pH at which the concentration of acid and conjugate base are equal

– As it can exist in 2 forms (acid and conjugate base) there is a point at which it is half-base/half-acid

Question 18

What does a lower pH mean (acids)?

Answer 18

More acid form / less conjugate base form

Question 19

What does a higher pH mean (acids)?

Answer 19

Less acid form / more conjugate base form

Question 20

What is multiple ionisation?

Answer 20

Not every dissociation of proton is the same

–e.g. phosphoric acid can lose 1/2/3 protons to gain respective charges

Question 21

What is true of acids and bases around their pKa?

Answer 21

Acids and their conjugate bases can act as buffers of H+ around their pKa

Question 22

What do buffers do?

Answer 22

They act to reduce the possibility of big pH changes when [H+] changes