Chapter 4

Question 1

hydrochloric acid

Answer 1

HCl

Question 2

sulfuric acid

Answer 2

H2SO4

Question 3

nitric acid

Answer 3

HNO3

Question 4

ethanoic acid/vinegar

Answer 4

CH3COOH

Question 5

acid characteristics

Answer 5

ph under 7
contains H in formulae
releases H+ ions in solution when dissolved in water

Question 6

strong acid

Answer 6

completely dissociates in aqueous solution

Question 7

weak acid

Answer 7

partially dissociates in aqueous solution

Question 8

base

Answer 8

neutralises an acid to form a salt

Question 9

alkali

Answer 9

base that dissolves in water and releases OH- ions

Question 10

metal oxides

Answer 10

MgO
CaO
CuO

Question 11

metal carbonates

Answer 11

Na2CO3
CaCO3
CuCO3

Question 12

alkali

Answer 12

NaOH
KOH
NH3

Question 13

acid +alkali ->

Answer 13

salt + water

Question 14

acid + metal oxide ->

Answer 14

salt + water

Question 15

acid +metal carbonate ->

Answer 15

salt + water+ carbon dioxide

Question 16

acid+ metal ->

Answer 16

salt +hydrogen

Question 17

neutralisation

Answer 17

H+ and OH– to form H2O

Question 18

• The student prepares a 250.0 cm3 solution from 1.513 g of A.
• The solution of A is added to the burette and titrated with 25.0 cm3 volumes of 0.112 mol
  dm−3 NaOH(aq).
• 1 mol of A reacts with 2 mol of NaOH.
• The student obtains a mean titre of 27.30 cm3.
  i. Calculate the molar mass of A from these results.

Answer 18

n(NaOH) = 0.112 x 25/1000 = 0.00280
n(A) IN 25cm3 = 0.00280/2 = 0.00140
n(A) in 250cm3 = 0.00140 x 250/27.30= 0.0128
Mr(A) = 1.513/ 0.0128 = 118g mol-1

Question 19

titration

Answer 19

technique used to accurately measure the volume of one solution that reacts exactly with another

Question 20

titrations used for

Answer 20

finding concentration of a solution
identification of unknown chemicals
finding purity of a substance

Question 21

standard solution

Answer 21

solution of known concentration

Question 22

preparing a standard solution

Answer 22

1. solid is weighed and dissolved using less water than needed to fill
2. solution is transferred to a volumetric flask (last bits rinsed with distilled water)
3. flask filled to graduation line by adding water drop at a time until bottom of meniscus aligns
4. invert flask to mix the solution thoroughly

Question 23

acid- base titration procedure

Answer 23

1. add measured volume of one solution to conical flask
2. add the other solution to a burette and record initial reading to 0.05 nearest
3. add indicator to conical flask
4. run solution in whilst swirling- colour change= end point of titration
5. record final reading, difference= titre
   (trial is done to find approximate titre) then is repeated accurately until two titres are concordant

Question 24

concordant

Answer 24

within 0.10m3 of eachother