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Match the acids given in Column (A) with their correct source given in Column (B).
|
Column (A) |
Column (B) |
|
(a) Lactic acid |
(i) Tomato |
|
(b) Acetic acid |
(ii) Lemon |
|
(c)Citric acid |
(iii) Vinegar |
|
(d) Oxalic acid |
(iv) Curd |
Answer
Based on the presence of acid in the given substance;
- → iv
- → iii
- → ii
- → i
Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.
Answer
Acid present in ant sting - Methanoic acid (Formic acid)
Chemical formula - HCOOH
Method to get relief - Applying a paste of baking soda (Na 2 CO 3 ) on it
How would you distinguish between baking powder and washing soda by heating?
Answer
On heating Baking powder (NaHCO 3 ), CO 2 gas is released
This gas on passing through limewater, turns milky
On heating Washing soda (Na 2 CO 3 .10H 2 O), no gas evolves
It just loses its water of crystallization and it turns into an amorphous powder.
Na 2 CO 3 .10H 2 O → Na 2 CO 3 + 10H 2 O
Salt A commonly used in bakery products on heating gets converted into another salt B which itself is used for removal of hardness of water and a gas C is evolved. The gas C when passed through lime water, turns it milky. Identify A, B and C.
Answer
Salt used in bakery products - Salt A - Baking soda - NaHCO 3 (Sodium Hydrogen Carbonate)
On heating Baking powder (NaHCO 3 );
2NaHCO 3 → Na 2 CO 3 + CO 2 + H 2 O
Salt A Salt B Gas C
- Salt B - Baking powder - Na 2 CO 3 (Sodium Carbonate) is formed which is used to remove hardness of water
- CO 2 gas is released and on passing through limewater, turns milky due to formation of Calcium Carbonate
Ca(OH) 2 + CO 2 → CaCO 3 + H 2 O
In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as a by-product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in the chemical industry. Identify X and Y giving the chemical equation of the reactions involved.
Answer
Industrial process for manufacturing NaOH ;
Electricity is passed through salt water (called brine), to form Sodium Hydroxide (NaOH), Chlorine and Water. The process is called the chlor-alkali process.
2NaCl(aq) + 2H 2 O(l) → 2NaOH(aq) + Cl 2 (g) + H 2 (g)
‘Gas X’
Manufacture of Bleaching powder ;
Chlorine produced in the process of making Sodium Hydroxide is used for the manufacture of Bleaching powder. The Chlorine reacts with dry slaked lime (Ca(OH) 2 ) to produce bleaching powder (CaOCl 2 ).
Ca(OH) 2 + Cl 2 → CaOCl 2 + H 2 O
‘Bleaching powder’
So, X is Cl 2 and Y is CaOCl 2
A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identify X, Y, G and Z.
Answer
The metal Carbonate ‘X’ is Calcium Carbonate ;
CaCO 3 + HCl → CaCl 2 + CO 2 + H 2 O
‘X’ Acid Gas
Ca(OH) 2 + CO 2 → CaCO 3 + H 2 O
‘Y’ Gas ‘X’
The solution ‘Y’ is Calcium Hydroxide
2NaCl + 2H 2 O → 2NaOH + Cl 2 + H 2
‘G’
(Brine) (Anode) (Cathode)
The gas ‘G’ obtained at Cathode is Chlorine
Ca(OH) 2 + Cl 2 → CaOCl 2 + H 2 O
Dry slaked lime ‘G’ ‘Z’
The compound used for disinfection of water, ‘Z’ is Calcium Oxychloride
Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.
Answer
Compound ‘X’ is Sodium Hydroxide
2NaOH + Zn → Na 2 ZnO 2 + H 2 (g)
‘X’ ‘A’
Compound ‘A’ is Sodium Zincate
NaOH + HCl → NaCl + H 2 O
‘X’ ‘B’
Compound ‘B’ is Sodium Chloride
NaOH + CH 3 COOH → CH 3 COONa + H 2 O
‘X’ ‘C’
Compound ‘C’ is Sodium Ethanoate
Match the important chemicals given in Column (A) with the chemical formulae given in Column (B).
|
Column A |
Column B |
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(i) CaOH 2 |
|
(ii) CaSO 4 . ½ H 2 O |
|
(iii) CaSO 4 . 2H 2 O |
|
(iv) CaOCl 2 |
Answer
- → ii Plaster of Paris → CaSO 4 . ½ H 2 O
- → iii Gypsum → CaSO 4 . 2H 2 O
- → iv Bleaching Powder → CaOCl 2
- → i Slaked Lime → CaOH 2
Fill in the missing data in the following data.
|
Name of the salt |
Formula |
Salt obtained from |
|
|
Base |
Acid |
||
|
Ammonium Chloride |
NH 4 Cl |
NH 4 OH |
|
|
Copper Sulphate |
H 2 SO 4 |
||
|
Sodium Chloride |
NaCl |
NaOH |
|
|
Magnesium Nitrate |
Mg(NO 3 ) 2 |
HNO 3 |
|
|
Potassium Sulphate |
K 2 SO 4 |
||
|
Calcium Nitrate |
Ca(NO 3 ) 2 |
Ca(OH) 2 |
|
Answer
|
Name of the salt |
Formula |
Salt obtained from |
|
|
Base |
Acid |
||
|
Ammonium Chloride |
NH 4 Cl |
NH 4 OH |
HCl |
|
Copper Sulphate |
CuSO 4 |
Cu(OH) 2 |
H 2 SO 4 |
|
Sodium Chloride |
NaCl |
NaOH |
HCl |
|
Magnesium Nitrate |
Mg(NO 3 ) 2 |
Mg(OH) 2 |
HNO 3 |
|
Potassium Sulphate |
K 2 SO 4 |
KOH |
H 2 SO 4 |
|
Calcium Nitrate |
Ca(NO 3 ) 2 |
Ca(OH) 2 |
HNO 3 |
In the following schematic diagram for the preparation of hydrogen gas as shown in the given figure, what would happen if following changes are made ?
- In place of zinc granules, the same amount of zinc dust is taken in the test tube.
- Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.
- In place of zinc, copper turnings are taken.
- Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.
Answer
-
Zinc dust will have more surface area compared to Zinc granules.
More surface area of metal means rate of reaction will be more
Reaction will be faster with zinc dust as against zinc granules
-
The reaction will proceed at almost the same rate
The H 2 gas produced will be nearly the same amount
-
According to reactivity series, Copper is less reactive than Hydrogen
So reaction will not take place if Copper is taken in place of Zinc
- The reaction will be as follows:
2NaOH + Zn → Na 2 ZnO 2 + H 2 (g)
Sodium Zincate
For making cake, baking powder is taken. If at home your mother uses baking soda instead of baking powder in cake.
- How will it affect the taste of the cake and why?
- How can baking soda be converted into baking powder?
- What is the role of tartaric acid added to baking soda?
Answer
-
Baking soda will
react to form Sodium Carbonate
(Na
2
CO
3
)
This will bring about a bitter taste to the cake as Na 2 CO 3 is a base.
-
Baking soda can be converted to baking powder
upon heating
. The reaction is as follows;
2NaHCO 3 → Na 2 CO 3 + CO 2 + H 2 O
Baking soda Baking powder
-
Tartaric acid and Sodium Carbonate undergo
neutralization reaction
.
As a result, the cake will not taste bitter .
