2P03: pH Changes

Results part 1

Volume of diluted sodium hydroxide added (cm cube)	Total volume of diluted sodium hydroxide added (cm cube)	pH
0	0	1
2	2	1
2	4	1
2	8	1
2	10	1
2	12	2
2	14	2
2	16	2
2	18	2
2	20	2
2	22	8
3	25	14

Initial à1

Final à7

Exercise

1 (i) Hydrochloric acid + sodium hydroxide à sodium chloride + water

(ii) Hydrochloric acid + copper (II) oxied à copper chloride + water

2. 25, 25, end-point of acid

3. increases, decreases

4. (i) 14

(ii) 7

Draw the graph in a smooth line according to the results (Better if you were to use a graph paper, be neat) J

2P2 Group 9 --- 2P07 Answer Scheme

Colour of gas:

Sodium Hydroxide + Ammonium chloride: Colourless

Calcium hydroxide + ammonium nitrate: Colourless

Odour:

Sodium~: pungent

Calcium~: pungent

Damp Red litmus paper:

Sodium~: Turns blue

Calcium~: Turns blue

Damp blue litmus paper:

Sodium~: Remains blue

Calcium: Remains blue

Name of gas formed: Ammonia

Conclusion

1)      Ammonia

2)      Alkali + ammonium salts = salt + water + ammonia gas

3)      The mixture must be heated to evaporate the ammonia gas from the solution

4)      Ammonia gas is alkaline in nature

5)      Alkalis only show its properties in water

6)      Heat a mixture of X and sodium hydroxide. If x is ammonia salt, there would be a colourless and pungent gas. It would turn red litmus paper blue. The gas would be ammonia gas.

7)      Ammonium nitrate can react with calcium hydroxide to form calcium nitrate, water and ammonia.

Exercise:

1a) sodium hydroxide + ammonium chloride à sodium chloride + ammonia + water

b) NaOH + NH4Cl à NaCl + NH3 + H2O

2a) sodium hydroxide + ammonium sulfate à sodium sulfate + ammonia + water

b) 2NaOH + (NH4)2SO4 à Na2SO4 + 2NH3 + 2H2O

3a) sodium hydroxide + ammonium nitrate à sodium nitrate + ammonia + water

b) NaOH + NH4NO3 à NaNO3 + NH3 + H2O

4a) calcium hydroxide + ammonium chloride à calcium + ammonia + water

b) Ca(OH)2 + 2NH4Cl à CaCl2 + 2NH3 + 2H2O

5a) calcium hydroxide + ammonium sulfate à calcium sulfate + ammonia + water

b)  Ca(OH)2 + (NH4)2SO4 à CaSO4 +2NH3 + 2H2O

6a) calcium hydroxide + ammonium nitrate à calcium nitrate + ammonia + water

b) Ca(OH)2 + 2NH4NO3 à Ca(NO3)2 + 2NH3 + H2O

Model Answers for 2P07

2P07.
Observations
                       Sodium hydroxide+ammonium chloride        Calcium hydroxide +ammonium nitrate
Colour of gas                  Colourless                                                    Colourless
Odour of gas                   Pungent                                                        Pungent
Effect of gas on damp
: Red Litmus Paper          Turns Blue                                                    Turns blue
: Blue Litmus Paper          No visible change is observed.                    No visible change is observed.
Name of gas formed        Ammonia                                                      Ammonia

Conclusion (answers)
1. ammonia
2.Alkali+ammonium salt -->salt+water+ammonia gas
3.It is necessary to warm the mixture to evaporate ammona gas from the solution.
4. Ammonia gas is alkaline in nature.
5.An alkali only shows its alkaline properties in the presence of water.
6.Heat a mixture of substance X and sodium hydroxide .If X is an ammonium salt , a colourless and pungent gas which turned moist red litmus paper blue will be observed. The gas is ammonia.
7. Ammonium nitrate can react with calcium hydroxide to form calcium nitrate ,water and ammonia.

Exercise
1. sodium hydroxide+ammonium chloride->sodium chloride+water+ammonia gas
  NaOH+NH4CL->NaCL+H20+NH3
2. sodium hydroxide+ammonium sulfate->sodium sulfate+water+ammonia gas
(NH4)2 SO4 -> Na2SO4->2H20+2NH3
3.sodium hydroxide +ammonium nitrate  --------->sodium nitrate + water +ammonia gas
NaOH+NH4NO3 --------->NaNO3+H2O+NH3
4.calcium hydroxide +ammonium sulfate  --------->calcium sulfate +water +ammonia gas
Ca(OH)2 + 2NH4Cl --------->CaCl2+2H2O+2NH3
5.calcium hydroxide + ammonium sulfate  --------->calcium sulfate+water +ammonia gas
Ca(OH)2 +(NH4)2SO4 --------->CaSO4 +2H20 +2NH3
6.calcium hydroxide +ammonium nitrate  ---------> calcium nitrate +water+ammonia gas
Ca(OH)2 + 2NH4NO3  --------->Ca(NO3)2+2H2O+2NH3

BY LIM WAN JIE   GOH HAO WEI   THIO TENG KIAT

2P2 group 4 practical 2P05

Q  Observation when carbonate is added to acid.

Effervescence of colourless and odourless gas was observed.

Q  Lime water

A white precipitate was formed

Q Damp litmus paper

Damp blue litmus paper turns red

Q conclusion

1.

Dilute acid reacts with a carbonate to produce carbon dioxide gas

2.

Acid + carbonate = salt + water + carbon dioxide

3.

Differences:

Effervescence of colourless and odourless gas which formed a white precipitate in limewater was observed in the first experiment, while no gas was evolved in this experiment

A white precipitate is formed in limewater in the first experiment, while there is no visible change in this experiment

The damp blue litmus paper turned red in the first experiment, while there is not visible change in this experiment.

Explanation:

The reaction between calcium carbonate and sulfuric acid is incomplete. The product, calcium sulfide, is insoluble in water. It will form a coating around the insoluble calcium carbonate. Hence, prevent further reaction from taking place.

4. 

Bubble the gas through limewater. If the gas is carbon dioxide, a white precipitate will be formed.

5 (a) acidic

(b) Bubble the sample of air through limewater. Carbon dioxide gas in the air will react with limewater (calcium hydroxide) to form an insoluble product, calcium carbonate. Thus, removing the carbon dioxide from the air.

Exercise

1 (a) calcium carbonate + hydrochloric  acid--> calcium chloride + carbon dioxide+ water

CaCO3 + 2HCl --> CaCl2 + CO2 + H2O

Sodium carbonate + hydrochloric acid --> sodium chloride + water + carbon dioxide

Na2CO3 + 2HCl --> 2NaCl + H2O + CO2

Potassium carbonate + hydrochloric acid--> potassium chloride + water + carbon dioxide

K2CO3 + 2HCl --> 2KCl + H2O + CO2

Calcium carbonate + nitric acid--> calcium nitrate + water + carbon dioxide

CaCO3 + 2HNO3 --> Ca(NO3)2 + H2O + CO2

Sodium carbonate + nitric acid --> sodium nitrate + water + carbon dioxide

Na2CO3 + 2HNO3 --> 2NaNO3 + H2O + CO2

Potassium carbonate + nitric acid --> potassium nitrate + water + carbon dioxide

K2CO3 + 2HNO3 --> 2KNO3 + H2O + CO2

2P2 Group8

Thio Teng Kiat, Goh Hao Wei and Lim Wan Jie


answers to practical 2p07 : when alkali meets ammonium salts...

Group 7: 2P06

Observations:
A white solid is formed. It is salty in taste.

Conclusion: 
An acid reacts with an alkali to produce a salt.

Exercise:
1 (a) hydrochloric acid + sodium hydroxide -> sodium chloride + water
   (b) HCl + NaOH -> NaCl + H2O

2 (a) hydrochloric acid + potassium hydroxide -> potassium chloride + water
   (b) HCl + KOH -> KCl + H2O

3 (a) hydrochloric acid + calcium hydroxide -> calcium chloride + water
   (b) 2HCl + Ca(OH)2 -> CaCl2 + 2H2O

4 (a) nitric acid + sodium hydroxide -> sodium nitrate + water
   (b) HNO3 + NaOH -> NaNO3 + H2O

5 (a) nitric acid + potassium hydroxide -> potassium nitrate + water
   (b)HNO3 + KOH -> KNO3 + H2O

6 (a) nitric acid + calcium hydroxide -> calcium nitrate + water
   (b) HNO3 + Ca(OH)2 -> Ca(NO3)2 + 2H2O

7 (a) sulfuric acid + sodium hydroxide -> sodium sulphate + water
   (b) H2SO4 + 2NaOH -> Na2SO4 + 2H2O

8 (a) sulfuric acid + potassium hydroxide -> potassium sulphate + water
   (b) H2SO4 + 2KOH -> K2SO4 + 2H2O


9 (a) sulfuric acid + calcium hydroxide -> calcium sulphate + water
   (b) H2SO4 + Ca(OH)2 -> CaSO4 + 2H2O

10 (a) hydrochloric acid + ammonia solution -> ammonium chloride + water
     (b) HCl + NH3 -> NH4Cl + H2O
     (c)   - 

11 (a) nitric acid + amonium solution -> ammonium sulphate + water
     (b) HNO3 + NH3. -> NH4NO3 + H2O
     (c)   - 
12 (a) sulphate acid + ammonia solution -> ammonium sulphate + water
     (b) H2SO4 + 2NH3. -> (NH4)2SO4 + 2H2O
     (c)   - 

2p206 group 6

part 1

observation
salt is produced.

Conclusion
When a acid mixes with a alkali, the products of the reaction would be salt and water.

part 2
1a) hydrochloric acid + sodium hydroxide > sodium chloride  + water
1b) HCl + NaOH > NaCl +H2O

2a) hydrochloric acid + potassium hydroxide > potassium chloride + water
2b) HCl + KOH > KCl + H2O

3a) hydrochloric acid + calcium hydroxide > calcium chloride + water
3b) HCl + CaOH > CaCl + H2O

4a) nitric acid + sodium hydroxide > sodium nitrate + water
4b) 2HNO3 + NaOH > NaNO2 + H2O

5a) nitric acid + potassium hydroxide  > potassium nitrate + water
5b) 2HNO3 + KOH > KNO2 + H2O

6a) nitric acid + calcium hydroxide > calcium nitrate + water
6b) 2HNO3 + CaOH> CaNO2 + H2O

7a) sulfuric acid + sodium hydroxide > sodium sulphate + water
7b) H2SO4 + NaOH > NaSO4 + H2O

8a) sufuric acid + potassium hydroxide > potassium sulphate + water
8b) H2SO4 + KOH > KSO4 + H2O

9a) sulfuric acid + calcium hydroxide > calcium sulphate + water
9b) H2SO4 + CaOH > CaSO4 + H2O

10a) Hydrochloric acid + ammonia solution > ammonium chloride + water
10b) HCl + NH3 > NHCl + H2O

11a) nitric acid + ammonia solution > ammonium nitrate + water
11b) H2NO3 + NH3 > NHNO3 + H2O

12a) sulfuric acid + ammonia solution > ammonium sulphate + water
12b) H2SO4 + NH3 > NHSO4 + H2O

Group 2 - 2P04

Group 2 - 2P04

2P04 Assignment

Observations                     Magnesium          Iron           Zinc            Copper

Observation when metal   Bubbles are formed and      Some bubbles    Nothing is
is added to acid                 rise to the surface.               are formed          seen
                                                                                    
Effect of gas on burning   A 'pop' sound can be       The splint    
(lighted) splint                   heard and the splint         burned out      
                                          burned out
Effect of gas on damp       Damp red litmus paper remained red
red litmus paper

Effect of gas on damp       Damp blue litmus paper  Blue turned
blue litmus paper               remained blue                 red

Name of gas formed                  Hydrogen Gas

Chemical Formula of                       H2
gas

Conclusion


1. Dilute acids react with reactive metals to produce Hydrogen Gas.

2. Dilute acid + Metals --> Salt + Hydrogen Gas

3. I can identify it by looking at the bubbles formed and sound produced by the burning splint, such as a 'pop' sound when hydrogen is present.

4. It has a neutral pH.

5. Magnesium, Iron, Zinc, Copper


Exercise

1a) Magnesium + Hydrochloric Acid Magnesium Chloride + Hydrogen

1b) Mg + 2HCl MgCl2 + H2

2a) Iron + Hydrochloric Acid Iron (II) Chloride + Hydrogen

2b) Fe + 2HCl FeCl2 + H2

3a) Zinc + Hydrochloric Acid Zinc Chloride + Hydrogen

3b) Zn + 2HCl ZnCl2 + H2

4a) Magnesium + Sulfuric Acid Magnesium sulfate + Hydrogen

4b) Mg + H2SO4 MgSO4 + H2

5a) Iron + Sulfuric Acid Iron Sulfate + Hydrogen

5b) Fe + H2SO4 FeSO4 + H2

6a) Zinc + Sulfuric Acid Zinc Sulfate + Hydrogen

6b) Zn + H2SO4 ZnSO4 + H2

7a) Magnesium + Nitric Acid Magnesium Nitrate + Hydrogen

7b) Mg +2 H2NO3 Mg(NO3)2 + 2H2

8a) Iron + Nitric acid Iron(II) nitrate + Hydrogen

8B) Fe + 2H2NO3 Fe(NO3)2 + 2H2

9a) Zinc + Nitric acid Zinc nitrate + Hydrogen

9b) Zn + 2H2NO3 Zn(NO3)2 + 2H2

2p03 Assignment

Part 1

pH

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

3.0

3.0

5.0

7.0

Part 2

Initial=1.0

Final=7.0

Exercise:

1 i) hydrochloric acid + sodium hydroxide -> sodium chloride + water

ii) hydrochloric acid + copper (II)oxide - > copper chloride + water

2 From your graph, what is the volume of sodium hydroxide needed  to neutralize the acid provided_? Volume = 25 cm cubed

Hence, 25cm cubed is known as the _____-_______ of __________

3 increases, decreases
4 i) pH=8.0

ii) pH=8.0

5 rises and stays the same