acids and bases

Question 1

define bronsted lowry acid

Answer 1

is a proton donor

Question 2

define bronsted lowry base

Answer 2

proton acceptor

Question 3

what is an amphoteric

Answer 3

a compound (usually a metal oxide or hydroxide) that can act as both an acid and a base

Question 4

what can you say about the equilibrium of acids and bases

Answer 4

-strong acids and strong bases fully ionise in water so they do not have equilibrium
-weak acids and weak bases partially ionise in water so their equilibrium lies to the left so kc values are very small

Question 5

what the equation for pH

Answer 5

pH=-log10[H+]

Question 5

whats the quation for [H+]

Answer 5

10^-log

Question 6

whats the equation for Kw

Answer 6

kw= [H+}^2

Question 7

if Kw isnt given what value should you assume it to be

Answer 7

1x10^-14

Question 8

explain why in Kw [H+]=[OH-]

Answer 8

pure water is neutral so the hydrogen ion conc is equal to the hydroxide ion conc (the H+ and OH- are in 1:1)

Question 9

when breaking water bonds is that an endothermic or exothermic reaction

Answer 9

endothermic therefore Kw is dependent on temperature

(MEXican BEN: Making bonds is EXOthermic and Breaking bonds is ENDothermic)

Question 10

explain why Kw increases with temperature

Answer 10

-position of equilibrium shifts to the right, the endothermic direction
-to oppose the increase in temperature

Question 11

what is a monoprotic base

Answer 11

base that can accept one proton e.gNaOH

Question 12

what is a diprotic base

Answer 12

base that can accept two protons e.g. Ba(OH)2

Question 13

whats the equation for a weak acid

Answer 13

Ka= [H+] [A-]/[HA]

Question 14

whats the equation for pKa

Answer 14

pKa= -logKa

Question 15

whats the equation for Ka from a pKa value

Answer 15

Ka=10-pKa

Question 16

what is the relationship between the value of pKa and the strength of the acid

Answer 16

-high value of pKa is a weaker acid(low Ka value)
-low value of pKa is a strong acid (high Ka value)

Question 17

what is a buffer solution

Answer 17

solution that maintains a constant pH despite the addition of acid, base or water

Question 18

what are the two types of buffers

Answer 18

acidic which have a pH of below 7
basic which have a pH of above 7

Question 19

what are acidic buffers made out of

Answer 19

-weak acid(HA) and its salts(A-)

Question 20

whats the template of how to answer buffer ‘expalin’ questions

Answer 20

-write the buffer equilibrium equation
-what does the added chemical react with
-which way does the equilibrium shift

Question 21

explain what happens when an acidic buffer is added an acid or a base

Answer 21

HA<—>H+ +A-
addition of acid:
added H+ reacts with A-
eqm shifts to left to decrease H+

addition of base:
-added OH- reacts with H+
-eqm shifts to the right to replace H+