acids + bases

Question 1

acid + metal ?

Answer 1

salt + hydrogen

Question 2

acid + metal oxide ?

Answer 2

salt + water

Question 3

acid + metal hydroxide ?

Answer 3

salt + water

Question 4

acid + metal carbonate ?

Answer 4

salt + co2 + water

Question 5

How to calculate PH of a weak acid

Answer 5

-log{square root}Ka[HA]

Question 6

how to calculate the PH of a strong alkali

Answer 6

-log(kw/[oh])

Question 7

define an acid

Answer 7

an acid is a proton donor

Question 8

define an alkali

Answer 8

an alkali is a proton acceptor

Question 9

how to calculate concentration of H+ ions

Answer 9

[H+] = 10^-ph

Question 10

a strong acid?

Answer 10

fully dissocaites into H+ ions

Question 11

a weak acid?

Answer 11

partially dissociates into H+ ions

Question 12

definition of a buffer ?

Answer 12

a solution which can resist changes in pH when small amount of acid or base is added

Question 13

def of an acidic buffer

Answer 13

made of a weak acid and soluble salt of that acid
maintains pH below 7

Question 14

def of a basic buffer ?

Answer 14

made of a weak base and a soluble salt of that base.
maintains a pH above 7

Question 15

how to carry out acid base titrations

Answer 15

-fill burette with acid of known conc
-accurately measure out 25cm^3 of the alkali solution using pipette and transfer to conical flask
-add few drops of suitable indicator to the alkali
-slowly add acid from burette into conical flask, swirl constantly.as soon as indicator changes colour the solution has turned neutral so stop adding acid.reoerd the volume of acid added
-repeat process tilll two results which are concordant (0.1+ or -) mean of these two is average titre
-used to calc unknown conc

Question 16

alternative method to carry out pH titrations

Answer 16

-measure pH of acid and record
-add 1cm^3 of base solution
-stir mixture
-measure pH and record
-repeat process until base in excess
-add base in smaller increments near end point