For CBSE Student: CPS and SDV
1. Match the important chemicals given in Column (A) with the chemical formulae given in Column (B)
Column (A) Column (B)
(a) Plaster of Paris (i) Ca(OH)2
(b) Gypsum (ii) CaSO4.1/2 H2O
(c) Bleaching Powder (iii) CaSO4.2H2O
(d) Slaked Lime (iv) CaOCl2
2. 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.
3. What happens when nitric acid is added to egg shell?
4. How would you distinguish between baking powder and washing soda by heating?
5. 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.
6. In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.
7. What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.
8. When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilized in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.
9.Why aqueous solution of sodium carbonate is basic in nature?
10.Why is an aqueous solution of ammonium chloride acidic in nature?
Answer
1. (a)— (ii) (b)— (iii) (c)— (iv) (d)— (i)
2. The acid present in ant sting is methanoic acid (formic acid). The chemical formula is HCOOH. To get relief one should apply any available basic salt e.g., baking soda (NaHCO3) on it.
Column (A) Column (B)
(a) Plaster of Paris (i) Ca(OH)2
(b) Gypsum (ii) CaSO4.1/2 H2O
(c) Bleaching Powder (iii) CaSO4.2H2O
(d) Slaked Lime (iv) CaOCl2
2. 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.
3. What happens when nitric acid is added to egg shell?
4. How would you distinguish between baking powder and washing soda by heating?
5. 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.
6. In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.
7. What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.
8. When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilized in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.
9.Why aqueous solution of sodium carbonate is basic in nature?
10.Why is an aqueous solution of ammonium chloride acidic in nature?
Answer
1. (a)— (ii) (b)— (iii) (c)— (iv) (d)— (i)
2. The acid present in ant sting is methanoic acid (formic acid). The chemical formula is HCOOH. To get relief one should apply any available basic salt e.g., baking soda (NaHCO3) on it.
3. Egg shells contain calcium carbonate. When nitric acid is added to it, carbon dioxide gas is evolved. The reaction can be given as CaCO3 + 2HNO3 → Ca (NO3)2 + H2O + CO2
4. The chemical formula of baking powder is sodium hydrogen carbonate (NaHCO3). Whereas, that of washing soda is sodium carbonate (Na2CO3.10H2O)Sodium hydrogencarbonate on heating gives CO2 gas which will turn lime water milky whereas no such gas is obtained from sodium carbonate.
2NaHCO3 ---Heat→ Na2CO3 + H2O + CO2
Na2CO3.10H2O -Heat→ Na2CO3 + 10H2O
5. Baking powder (NaHCO3), salt A is commonly used in bakery products. On heating it forms sodium carbonate (Na2CO3), B and CO2 gas, C is evolved. When CO2 gas is passed through lime water it forms calcium carbonate (CaCO3), which is slightly soluble in water making it milky
A – NaHCO3 B – Na2CO3 C - CO2
4. The chemical formula of baking powder is sodium hydrogen carbonate (NaHCO3). Whereas, that of washing soda is sodium carbonate (Na2CO3.10H2O)Sodium hydrogencarbonate on heating gives CO2 gas which will turn lime water milky whereas no such gas is obtained from sodium carbonate.
2NaHCO3 ---Heat→ Na2CO3 + H2O + CO2
Na2CO3.10H2O -Heat→ Na2CO3 + 10H2O
5. Baking powder (NaHCO3), salt A is commonly used in bakery products. On heating it forms sodium carbonate (Na2CO3), B and CO2 gas, C is evolved. When CO2 gas is passed through lime water it forms calcium carbonate (CaCO3), which is slightly soluble in water making it milky
A – NaHCO3 B – Na2CO3 C - CO2
6. In the manufacture of sodium hydroxide, hydrogen gas and chlorine gas (X) are formed as by–products. When chlorine gas (X) reacts with lime water, it forms calcium oxychloride (bleaching powder) Y. The reactions are
2NaCl (aq) + 2H2O(l) ---> 2NaOH (aq) + Cl2 (g) + H2(g)
X ---------> Cl2 (Chlorine gas)
Ca (OH)2 (s) + Cl2 (g) --------> CaOCl2 (s) + H2O
Y —> Calcium oxy chloride (bleaching powder)
7. In aqueous solutions strong acids ionize completely and provide hydronium ions. On the other hand weak acids are partially ionized and an aqueous solution of same molar concentration provides a much smaller concentration of H3O+ ions.
Strong acids — Hydrochloric acid, sulphuric acid, nitric acid
Weak acid — Citric acid, acetic acid, formic acid
8. When zinc reacts with dilute solution of strong acid, it forms salt and hydrogen gas is evolved.
Zn + 2HCl ------> ZnCl2 + H2
When a burning splinter is brought near the mouth of the test tube, the gas burns with a pop sound.
2NaCl (aq) + 2H2O(l) ---> 2NaOH (aq) + Cl2 (g) + H2(g)
X ---------> Cl2 (Chlorine gas)
Ca (OH)2 (s) + Cl2 (g) --------> CaOCl2 (s) + H2O
Y —> Calcium oxy chloride (bleaching powder)
7. In aqueous solutions strong acids ionize completely and provide hydronium ions. On the other hand weak acids are partially ionized and an aqueous solution of same molar concentration provides a much smaller concentration of H3O+ ions.
Strong acids — Hydrochloric acid, sulphuric acid, nitric acid
Weak acid — Citric acid, acetic acid, formic acid
8. When zinc reacts with dilute solution of strong acid, it forms salt and hydrogen gas is evolved.
Zn + 2HCl ------> ZnCl2 + H2
When a burning splinter is brought near the mouth of the test tube, the gas burns with a pop sound.
9.Ans: Sodium bicarbonate is an amphoteric compound. Aqueous solutions are mildly alkaline due to the formation of carbonic acid and hydroxide ion:
NaHCO3 + H2O → H2CO3 + OH−
NaHCO3 + H2O → H2CO3 + OH−
10.A basic component is the one that produces hydroxide (OH-) ions when dissolved in water. In aqueous solution of ammonium chloride, ammonium ions (NH4+) first associate with H2O and form ammonia and hydroxide ions.
NH4Cl + H2O = NH4+ + HCl
NH4+ + H2O = NH3 + OH-
Since ammonium ions produce hydroxide ions, NH4+ are considered to be the basic components.
NH4Cl + H2O = NH4+ + HCl
NH4+ + H2O = NH3 + OH-
Since ammonium ions produce hydroxide ions, NH4+ are considered to be the basic components.
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