2P05 Answers Courtesy of Chen Dewei (Group 4)

OBSERVATIONS
When calcium carbonate is added to hydrochloric acid:
Effervescence is observed. NO white precipitate is formed.
Effect of gas on limewater:
White precipitate is observed
Effect of gas on damp litmus paper:
The gas turns blue litmus paper red, while for the red litmus paper, there is no observable change.


1. When a dilute acid and a carbonate react, a salt, carbon dioxide and water are produced.
2. Dilute acid + carbonate -> salt + carbon dioxide + water
3. 
1. A white precipitate is formed.
2. The reaction is more vigorous.
3. Different salts are formed (calcium chloride and calcium sulfate)
 EXPLANATION
 Calcium chloride is soluble in acid while calcium sulfate is insoluble in acid. Different salts are formed. H2SO4    has 2 hydrogen atoms, while HCl has only 1 hydrogen atom, thus there's more acidity and therefore the reaction will be more vigorous.
4. Place a tube to transport the gas to a test-tube of limewater. If a white precipitate is formed, the gas is carbon dioxide.
5 (a) acidic
   (b) Bubble the sample of air through limewater (calcium hydroxide). Since limewater is a base, carbon dioxide (an acidic gas) will react with it.
Calcium carbonate + Hydrochloric acid à calcium chloride + carbon dioxide + water

CaCO3 + 2HCl -> CaCl2 + CO2 + H2O

Sodium carbonate + hydrochloric acid à sodium chloride + carbon dioxide + water

Na2CO3 + 2HCl -> 2NaCl + CO2 + H2O

Potassium carbonate + hydrochloric acid à potassium chloride + carbon dioxide +water

K2CO3 + 2HCl -> 2KCl + CO2 + H2O

Calcium carbonate + nitric acid à calcium nitrate + carbon dioxide + water

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

Sodium carbonate + nitric acid à sodium nitrate + carbon dioxide + water

Na2CO3 + 2HNO3 -> 2NaNO3 + CO2 + H2O

Potassium carbonate + nitric acid à potassium nitrate + carbon dioxide + water

K2CO3 + 2HNO3 -> 2KNO3 + CO2 + H2O

Calcium carbonate + sulfuric acid à calcium sulfate + carbon dioxide + water

CaCO3 + H2SO4 -> CaSO4 + CO2 + H2O

Sodium carbonate + sulfuric acid à sodium sulfate + carbon dioxide + water

Na2CO3 + H2SO4 -> Na2SO4 + CO2 + H2O

Potassium carbonate + sulfuric acid à potassium sulfate + carbon dioxide + water

K2CO3 + H2SO4 -> K2SO4 + CO2 + H2O

Sodium carbonate + ethanoic acid à  sodium ethanoate + carbon dioxide + water

Na2CO3 + 2CH3COOH -> 2Ch3COONa + CO2 + H2O

Potassium carbonate + ethanoic acid à potassium ethanoate + carbon dioxide + water

K2CO3 + 2CH3COOH -> 2CH3COOK + CO2 + H2O

Calcium carbonate + ethanoic acid à calcium ethanoate + carbon dioxide + water

CaCO3 + 2CH3COOH -> (CH3COO)2Ca + CO2 + H2O

Practical Worksheet 4 done by Tay Wei Sheng(26) and Andy Low(02) (Linus and Gabriel did not do)

Obeservation when metal is added to acid : Magnesium (White precipitate is formed, magnesium is dissoleved and bubbling occurs and forms a colourless solution) , Iron (Green precipitate is formed and the iron fillings sank to the bottom) , Zinc (Zinc dissolved in the acid) , Copper (the copper turnings sank to the bottom)
Effect f gas on burning(lighted) splint: Magnesium (Lighted out the bruning splint with a 'pop' sound), Iron (lighted out buring splint with a 'pop' sound), Zinc (lighted out the burning splint with a 'pop' sound)
Effect of gas on damp litmus paper: Magnesium (Damp red litmus paper remained red) , Iron(red), Zinc(red)
Effect of gas on blue litmus paper: Magenuium (blue) , Iron (blue)
Chemical formula of gas : H2
1. hydrogen gas
2. dilute acid + metal -> Hydrogen gas + salt
3. A burning splint can be placed near the mouth of the test tube containing the dilute acids and metal and the gas formed. If a 'pop' sound will be heard if the gas hydrogen.
4. It is neutral.
5. magnesium, iron, zinc, copper.
1(a) Magnesium + hydrochloric acid -> hydrogen gas + magnesium chloride
(b) Mg(s) + 2HCl2(aq) + H2(g)
2(a) iron + hydrochloric acid-> zinc chloride + hydrogen gas
(b) Zn + 2HCl ->ZnCl2 + H2
3(a) zinc + hydrochloric acid -> zinc chloride + hydrogen gas
(b) Zn + 2HCl -> ZnCl2 + H2
4(a) magnesium + sulfuric acid ->Magnesium sulfate + water
(b) Mg(OH)2 + H2SO4 -> MgSO4 + 2H2O
5(a) iron + sulfuric acid -> Iron sulfate + hydrogen gas
(b) Fe(s) + H2SO4(aq) -> FeSO4(aq) + H2(aq)
7(a) magnesium + nitric acid -> magnesium nitrate + hydrogen gas
(b) Mg + HNO3 -> MgNO3 + H
8(a) iron + nitric acid -> iron nitrate + hydrogen gas
(b) Fe(s) +HNO3 -> H0g) + FeNO(l)
9(a) zinc + nitric acid -> zinc nitrate + hydrogen gas
(b) Zn(s) + HNO3(aq)-> H2(aq) + Zn(NO3)2(aq)

2P07(When Alkali Meets Ammonium Salts)--Done by Cheng Tong Wen, Joel Koh, Ong Yi kai, Alex wu

Observations
Gone through already in the science lab


Conclusion 
1)Alkali reacts with ammonium salt to produce metallic salt,water and ammonium gas.
2)Alkali + ammonium salt--> metallic salt + water + ammonium gas
3)It is because the reaction needs heat energy in order to help break the bonds in the compounds
4)I can conclude that ammonia gas is an alkali
5)The litmus paper must be damp in order for an observation to occur
6)  Mix Substance X with hydroxide. If it is ammonium gas, it will produce water + salt + ammonia. Use damp litmus papers and the gas will turn the red litmus paper blue and the blue litmus paper will remain blue.

7.     

E

1(a)i) Sodium Hydroxide + Ammonium Chloride -> Sodium Chloride + Ammonia(g) + Water

ii) NaOH + NH₄Cl -> NaCl+NH₃(g) +H₂O

2(b) i)Sodium Hydroxide + Ammonium Sulfate -> Sodium Sulfate + Ammonia(g) + Water

ii) 2NaOH + (NH₄)₂SO₄(aq) → Na₂SO₄(aq) + 2NH₃ + 2H₂O

3(c) i)Sodium Hydroxide + Ammonium Nitrate -> Sodium Nitrate + Ammonia(g) + Water

ii) NaOH + NH₄NO₃ -> NaNO₃ + NH₃ + H₂O

4(d) i)Calcium Hydroxide + Ammonium Chloride -> Calcium Chloride + Ammonia(g) + Water

         ii) Ca(OH)₂(aq) + 2NH₄Cl -> CaCl₂+ 2NH₃(g) + 2H₂O

5(e) i)Calcium Hydroxide + Ammonium Sulfate -> Calcium Sulphate + Ammonia + Water                               

ii) Ca(OH)₂ + (NH₄)₂SO₄ -> CaSO₄ + 2NH₃(g) + 2H₂O 

6(f) i)Calcium Hydroxide + Ammonium Nitrate ->  No possible reaction observed

2P07- Done By Lek Hong, Stanley Yuan and Choy Yu Yong

Practical 7

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 from red to BLUE	Turns from red to BLUE
(BLUE Litmus paper)	Remains BLUE	Remains BLUE
Name of Gas formed	Ammonia Gas	Ammonia Gas

Conclusion

1.       Alkali reacts with ammonium salt to produce metallic salt + water

2.       Alkali + Ammonium Salt =  Metallic Salts + Water + Ammonia Gas

3.       Without heating the mixture, the process of combining would be too slow for the ammonia gas to be captured with the litmus paper.

4.       Ammonia gas is an alkali.

5.       In order to test the acidity of a gas, the litmus paper must be damp or there would not be any visible reaction.

6.       Mix it with hydroxide. If it is ammonium gas, it will produce H₂O + salt + ammonia. (Red litmus paper will turn blue).

7.       When mixed, ammonia gas is formed (NH₃), so the nitrogen element which is needed for protein-making in plants, is lost in the atmosphere.

Exercise

1(a) Sodium Hydroxide + Ammonium Chloride -> Sodium Chloride + Ammonia(g) + Water

(b) NaOH + NH₄Cl -> NaCl+NH₃(g) +H₂O

2(a) Sodium Hydroxide + Ammonium Sulfate -> Sodium Sulfate + Ammonia(g) + Water

(b) 2NaOH + (NH₄)₂SO₄(aq) → Na₂SO₄(aq) + 2NH₃ + 2H₂O

3(a) Sodium Hydroxide + Ammonium Nitrate -> Sodium Nitrate + Ammonia(g) + Water

(b) NaOH + NH₄NO₃ -> NaNO₃ + NH₃ + H₂O

4(a) Calcium Hydroxide + Ammonium Chloride -> Calcium Chloride + Ammonia(g) + Water

(b) Ca(OH)₂(aq) + 2NH₄Cl -> CaCl₂+ 2NH₃(g) + 2H₂O

5(a) Calcium Hydroxide + Ammonium Sulfate -> Calcium Sulphate + Ammonia + Water

(b) Ca(OH)₂ + (NH₄)₂SO₄ -> CaSO₄ + 2NH₃(g) + 2H₂O

6(a) Calcium Hydroxide + Ammonium Nitrate -> Nothing Will Happen

done by only bryan( wallace, zhan peng and jia sheng did not do anything)

Observation when carbonate is added to acid
Effervescence of a colourless, odourless gas, white precipitate is formed.
Lime water
White precipitate is formed
Damp litmus paper
Blue damp litmus paper turns red, red damp litmus paper remains same
1. Salt, carbon dioxide and water
2 acid + metal carbonate>salt + carbon dioxide + water
4. Bubble the gas into lime water. I f white precipitate if formed, the gas is carbon dioxide.
5a. acidic
5b. Bubble the sample of air through aqueous sodium hydroxide. As sodium hydroxide is an alkaline, carbon dioxide, an acidic gas, will react with the aqueous sodium hydroxide.

Calcium carbonate + Hydrochloric acid à calcium chloride + carbon dioxide + water

Sodium carbonate + hydrochloride acid à sodium chloride + carbon dioxide +water

Potassium carbonate + hydrochloride acid à potassium chloride + carbon dioxide +water

Calcium carbonate + nitric acid à calcium nitrate + carbon dioxide + water

Sodium carbonate + nitric acid à sodium nitrate + carbon dioxide + water

Potassium carbonate + nitric acid à potassium nitrate + carbon dioxide + water

Calcium carbonate + sulfuric acid à calcium sulphate + carbon dioxide + water

Sodium carbonate + sulfuric acid à sodium sulphate + carbon dioxide + water

Potassium carbonate + sulfuric acid à potassium sulphate + carbon dioxide + water

Sodium carbonate + ethanoic acid à  sodium ethanoic + carbon dioxide + water

Potassium carbonate + ethanoic acid à potassium ethanoic + carbon dioxide + water

Calcium carbonate + ethanoic acid à calcium ethanoic + carbon dioxide + water

2P08 WenHong, WeiSheng, Zac and ManChin

Leow Wei Sheng

Zac Lee
1) CuSO₄^o5H₂O --> CuSO₄ + 5H₂O

2) Greyish- White

ManChin

3a) Observation: When you heat the copper (II) sulphate, it turns white 

      Explainaton:The water is driven off by the heat. The white residue remained are dehydrated copper (II) sulphate, also known as anhydrous.

WenHong

3b) Observation: The copper turned blue.

      Expaination : This is because the copper(II) sulphate is rehydrated and thus returning to its original colour.

Done by: Joel Chua (8) , Dae Koon (16) , Zhao Xiang (24) , Fan Pu (32) Practical 08 - Preparation of Soluble and Insoluble Salts

Page 1 - Dae Koon
Observations :

The colour changes from colourless to blue, and the powder disappears.The blue colour intensifies as more black powder is used.

Page 2 - Fanpu
Colour of filtrate: blue
Colour of residue: black
Name of filtrate: Copper (II) sulfate and water
Name of residue: Copper (II) oxide

1. H2SO4 + CuO --> CuSO4 + H2O
2. Blue

Page 3 - Joel Chua

3. Take a few of the Copper(II) sulfate crystals and place them on a cleaned, dry evaporating dish and heat for a few minutes.

a ) State and explain your observation.
The blue Copper(II) sulfate crystals becomes white Copper(II) sulfate powder. When Copper(II) sulfate is heated, it becomes dehydrated, and water is removed from it. The dehydrated compound that is formed is white. Hence, the Copper(II) sulfate changes from blue to white.

b) Add one drop of water on the residue left in a. State and explain your observations.
The residue in a turns blue. Previously, when the Copper(II) sulfate was heated, it became dehydrated, and the compound formed was white. However, when water is added to it, it becomes hydrated again, and turns back to its original colour, which is blue.


Page 4 - Zhao Xiang
4.Colour of filtrate: Blue
   Colour of residue: white
   Name of residue: lead(II)sulfate
1.Word equation: Pb(NO3)2 + CuSO4 --> PbSO4 + Cu(NO3)
   Chemical equation: Pb(NO3)2 + 2CuSO4 --> 2PbSO4 + 2Cu(NO3)

2P04: When Dilute Acid Meets Metals

2P04: When Dilute Acid Meets Metals...

View more documents from Alex Chen

Note: Answers for table for - "Observation when metal is added to acid" is unclear

Answers: Magnesium - White precipitate, efferencsence of a colourless, odourless gas.

Iron: Green precipitate, efferencsence of a colourless, odourless gas.

Zinc: White precipitate, efferencsence of a colourless, odourless gas.

Copper: No visible change

Done by: Alexander Chen, David Li, Lim Joo Bin, Soh Zhen Yang and Zhu Jiahua