Chemical reactions and equations
1. Why should a strip of magnesium be cleaned before combustion in air?
Answer:- A layer of alkaline magnesium carbonate is formed on the surface of the magnesium strip due to water vapor in the air. Because of this layer, the magnesium ribbon does not have direct contact with the oxygen in the air।
2. Write the balanced equations for the following chemical reactions।
(i) Hydrogen + chlorine → hydrogen chloride।
Answer:- H₂ + CI₂ → 2HCI
(ii) Barium chloride + Aluminum sulphate → Barium sulphate + Aluminum chloride
Answer:- BaCl₂ + AL₂(SO₄)₃ → BasO₄ + HERE₃
(iii) Sodium + water → sodium hydroxide + hydrogen।
Answer:- 2Na + 2H₂O → 2NaOH + H₂
3. Write a balanced chemical equation with state symbols for the following reactions।
(i) Aqueous solutions of barium chloride and sodium sulphate react to form insoluble barium sulphate and sodium chloride solutions।
Answer:- BaCl₂ + Already₂ SO₄ → BaSO₄ + 2NaC
(ii) Sodium hydrotoxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water।
Answer:- NaOH + HCI → NaCl + H₂THE
Questionnaire:
1. A solution of a substance 'X' is used for white washing.
(i) Write the name and symbol of substance 'X'।
Answer:- Substance 'X' is called burnt lime।
(ii) Write down the reaction of substance 'X' with water।
Answer:- The reaction of substance 'X' with water is one
CaO + H₂O → Ca(OH)₂ (burnt lime)
2. In Activity 1.7, in one test tube, why is the amount of gas collected twice the amount of gas collected in the other test tube? Name this gas।
Answer:- When hydrogen and oxygen combine in a 2:1 ratio, water is produced. That is, the water molecule has two hydrogen atoms attached to one oxygen atom, hence the symbol for water, H₂THE । The first gas is hydrogen and the second gas is oxygen।
Questionnaire:
1. Why does a copper sulphate solution change color when an iron pin is dipped?
Answer:- Since iron is more active than copper, iron removes copper from the copper sulphate solution when an iron pin is dipped in it. As a result, the concentration of the copper sulphate solution decreases and the blue color of the copper sulphate solution becomes pale and the iron pin becomes copper coloured।
2. Give an example of a double elimination reaction other than the one given in Activity 1.10।
Answer:- Silver nitrogen aqueous solution reacts with sodium chloride solution to form white precipitate of silver chloride and sodium nitrate solution।
AgNo3(aq) + NaCl(aq) à AgCl(s)↓ + NaNo3(aq)
3. Select the substances that are oxidized and deoxidized in the following reactions.
(i) 4Na(s) + O₂(g) → 2Na₂You)
Answer:- Na is released in this reaction ieSodium chloride is produced and oxygen is dissolved।
(ii) CuO(s) + H₂(g) → Cu(s) + H₂O(I)
Answer:- H₂ Water is produced by oxidation and CuO is oxidized to produce Cu।
Practitioner:
1. Which of the statements are incorrect for the following reaction?
2PbO(s) + C(s) → 2Pb(s) + CO₂(g)
(a) The lead is disturbed।
(b) Carbon dioxide is released।
(c) Carbon is released।
(d) Lead oxide is dissolved।
(i) (a) and (b)
(ii) (a) and (c)
(iii) (a), (b) and (c)
(iv) everything
Answer:- (a) and (b)।
2. Fe₂THE₃ + 2AI → AI2THE3 + 2Fe
The above reaction is an example
(a) of a coupling reaction
(b) of a bisubtraction reaction
(c) of a dissociation reaction
(d) of a subtraction reaction
Answer:- (d) of a subtraction reaction।
3. What happens when dilute hydrochloric acid is added to iron powder? Tick the correct answer।
(a) Hydrogen gas and iron chloride are produced।
(b) Chlorine gas and iron hydroxide are produced।
(c) No reaction occurs।
(d) Iron salts and water are produced।
Answer:- (a) Hydrogen gas and iron chloride are produced।
4. What is a balanced chemical equation? Why balance chemical equations?
Answer:- A chemical equation in which the reactant and the reactant contain an equal number of atoms for each element is called a balanced chemical equation।
H2 + Cl2 → 2HCl
2H₂ + O₂ → 2H₂ THE
According to the law of mass, mass is not created or destroyed in a chemical reaction. Therefore, in the reactions, the total mass of the reactants before the reaction must equal the total mass of the reactants after the reaction. Therefore, the chemical equations must be balanced।
5. Write and balance the following statements in the form of chemical equations.
(a) Hydrogen gas combines with nitrogen to form ammonia।
Answer:- Jonka chemical equation one
H2 + N2 → NH3
Balanced chemical equations one
3H₂(g) + H₂(g) → 2NH₃(g)
(b) Hydrogen sulphide burns in air to produce water and sulfur dioxide।
Answer:- Jonka chemical equation one
H2S + O2 → H2o + Sun2
Balanced chemical equations one
2H₂S(g) + 3O₂(g) → 2H₂O(l) + 2SO₂(g)
(c) Barium chloride reacts with aluminum sulphate to form precipitates of aluminum chloride and barium sulphate।
Answer:- Jonka chemical equation one
BaCl2 + Al2(So4)3 → AlCl3 + BaSo4
Balanced chemical equations one
3BaCl₂(ac) + Al(SO₄)₃(aq) → 2AICI₃(aq) + 3BaSO₄(S)
(d) Potassium metal reacts with water to form potassium hydroxide and hydrogen gas utThey are able to do this।
Answer:- Jonka chemical equation one
K + H2The → KOH + H2
Balanced chemical equations one
2K(s) + 2H₂O(l) → 2KOH + H₂(g)
6. Balance the following chemical equations।
(a) HNO3 + Ca(OH)2 → Ca (NO3)2 + H2THE
Answer:- 2 HNO₃ (aq) + Ca(OH)₂ (aq) → Ca(NO₃)₂ (aq) + 2H₂ A(l)
(b) NaOH + H₂SO₄ → That's it₂SO₄ + H₂THE
Answer:- 2NaOH(aq) + H₂SO₄ (aq) → Na₂ SO₄ (aq) + 2H₂Oh (aq)
(c) NaCl + AgNO₃ → AgCl + NaNO₃
Answer:- NaCl (aq) + AgNO₃ (aq) → AgCl (S) + NaNO₃ (aq)
(d) BaCl₂ + H₂SO₄ → BaSO₄ + HCI
Answer:- BaCl₂ (aq) + H₂SO₄ (aq) → BaCO₄ (S) + 2HCl (aq)
7. Write the balanced chemical equations for the following reactions।
(a) Calcium hydroxide + carbon dioxide → Calcium carbonate + water।
Answer:- Ca(OH)₂ (aq) + CO₂ (g) → CaCO₃ (s) + H₂O(l)
(b) Zinc + silver nitrate → zinc nitrate + silver।
Answer:- Zn (s) + 2AgNO₃ (aq) → Zn (NO₃)₂ (aq) + 2Ag (S)
(c) Aluminum + copper chloride → Aluminum chloride + copper।
Answer:- 2Al(s) + 3CuCI₂ (aq) → 2AICI₃ (aq) + 3Cu (S)
(d) Barium chloride + potassium sulfate → barium sulfate + potassium chloride।
Answer:- BaCl₂ (aq) + K₂SO₄ (aq) → BaCO₄ (S) + 2KCI (aq)
4. Write the balanced chemical equations for the following and identify each type of reaction।
(a) Potassium bromide (aq) + barium iodide (aq) → potassium iodide (aq) + barium bromide (s)
Answer:- 2KBr(aq) + Bal₂ (aq) → 2KI (aq) + BaBr₂ (S)
It is a double elimination reaction।
(b) Zinc carbonate (s) → Zinc oxide (s) + Carbon dioxide (g)
Answer:- ZnCO₃(s) → ZnO(S) + CO₂(g)
It is a decomposition reaction।
(c) Hydrogen (g) + Chlorine (g) → Hydrogen chloride(g)
Answer:- H₂(g) + Cl₂(g) → 2HCl(g)
It is an addition reaction।
(d) magnesium (s) + hydrochloric acid (aq) → magnesium chloride (aq) + hydrogen (g)
Answer:- Mg(s) + 2HCl (aq) → MgCI₂ (aq) + H₂ (g)
It is a subtraction reaction।
9. What are thermogenic and thermogenic reactions? Give examples।
Answer:- A chemical reaction in which heat is produced or released is called a thermodynamic reaction।
For example, CO burns in the presence of methane (natural gas) in air (oxygen).2 And H2They produce O as well as a considerable amount of heat energy।
CH4 (g) + 2O2 (g) → CO2 + 2H2O + heat energy
A reaction in which heat is absorbed is called a thermophilic reaction।
For example, N2 O of the air2 It absorbs a lot of heat to produce nitric oxide (NO) by reacting with it at very high temperatures (3,000oc).।
N₂ (g)+O₂ (g)
10. Why is respiration considered to be a thermophilic reaction? explain।
Answer:- Respiration produces a large amount of heat energy by oxidation of food in the cells in the presence of oxygen. Therefore, respiration is called a thermodynamic reaction।
C₆H₁₂THE₆ (aq) + 6O₂ (g) → 6CO₂ (g) + 6H₂THE₂(l) + 2820(kJ)
11. Why is dissociation reaction called the opposite of addition reaction? Write the equations for these reactions।
Answer:- In an addition reaction, two or more substances (elements or compounds) combine to produce a new substance. In a dissociation reaction, on the other hand, a compound for one chemical dissociates to form two or more substances. Therefore, dissociation reactions are called the opposite of addition reactions।
Below are examples of each type one
coupling reactions one
2H₂ (g)+O₂ (g) → 2H₂O(l)
2Mg(s) + O₂ (g) → 2MgO (s)
Fe (g) + S (s) → FeS (s)
dissociation reactions one
2H₂O(l) → 2H₂ (s) + O₂ (q)
CaCO₂ (s) → CaO (s) + CO₂ (g)
12. Write an equation for each of the dissociation reactions that take place with heat, light and electricity।
Answer:- Equations of dissociation reactions occurring with thermal energy one
CaCO₂(s) ––copper→ CaO(s) + CO₂(g)
Equations of dissociation reactions occurring with light energy one
2AgBr –––The sun's rays→ 2Ag + Br₂(g)
Equations of dissociation reactions occurring with electrical energy one
2H₂O(l) –––Electrical power→ 2H₂(g)+O₂(g)
13. What is the difference between elimination and bi-elimination reactions? Write the equations for these reactions।
Answer:- The difference between elimination and bielimination reactions is one
In a removal reaction, a more active element removes a less active element from the solution of its compound।
example ㅡ
(i) CuSO₄ + Zn → ZnSO₄ + With
(ii) CuSO₄ + Fe ⟶ FeSO₄ + With
In a double elimination reaction, aqueous solutions of two ionic compounds participate in the reaction and exchange ions between them to produce new reactants।
example one
(i) AgNO₃ + NaCl → AgCl + NaNO₃
(ii) AgNO₃ + CuCl₂ → AgCl + Cu(NO₃)₂
14. In silver refining, removal of silver from silver nitrate solution is carried out by copper metal. Write down the reaction involved।
Answer:- Cu(s) + 2AgNO₃ → Cu(NO₃) (aq) + 2Ag(S)
15. What is meant by precipitation reaction? Explain with examples।
Answer:- A chemical reaction that produces a subsidence is called a subsidence reaction।
example one
(i) When an aqueous solution of silver nitrate reacts with an aqueous solution of sodium chloride, a white precipitate of silver chloride and a solution of sodium nitrate are produced।
AgNO₃ (aq) + NaCl (aq) ⟶ AgCl(s) + NaNO₃ (aq)
(ii) When hydrogen sulphide gas is allowed to pass through an aqueous solution of copper sulphate, a black precipitate of copper sulphide and a solution of hydrogen sulphate are formedtis fifty
CuSO₄ (aq) + H₂S(g) ⟶ CuS(s) + H₂SO₄ (aq)
16. Gain and Loss of Oxygen Explain the following terms with two examples each by definition।
(a) Alarm।
(b) Radiation।
Answer:- Corrosion:- An oxidation reaction is a reaction in which oxygen is added to a substance। such as one
(i) Carbon dioxide is produced when carbon is burned in the presence of air। C(g) + O₂(g) ⟶ CO₂(g)
(ii) Magnesium oxide is produced when magnesium ribbon is burned in the presence of oxygen।
2Mg(s) + O₂(g) → 2MgO(s)
Bijaran:- A reaction in which a substance loses oxygen is called a decomposition reaction।
such as ー
(i) CuO(s) + H₂(g) → Cu(s) + H₂A(l)
Here oxygen has been removed from CuO।
(ii) ZnO(s) + C(s) ⟶ Zn(s) + CO(g)
Here oxygen has been removed from ZnO।
17. A bright velvet element 'X' turned black when heated in air. Name the element 'X' and the black compound produced।
Answer:- The bright velvet colored element 'X' is called copper (Cu) and the black compound produced is called copper oxide (CuO).
2Cu(s) + O₂(g) ⟶ 2CuO(s)
‘X’ Elements Black colored compounds।
18. Why do we paint iron objects?
Answer:- The air contains plenty of oxygen and water vapor. They react with iron to produce ferrous ferric oxide. which we call wax. This wax corrodes iron objects. Therefore, coating iron objects with paint prevents the object from being caught by wax and prevents the object from deteriorating. As a result, the item stays good for a long time।
19. Why are foods containing oils and fats packaged in a nitrogen atmosphere?
Answer:- Foods containing oils and fats oxidize in the presence of oxygen in the air and smell bad. Nitrogen is an antioxidant. Therefore, foods containing oil or fat are not burnt when packaged in the presence of nitrogen. As a result, it stays good for many days।
20. Explain the following terms with an example।
(a) Attrition।
Answer:- Corrosion is the process by which a metal is exposed to various substances around it such as water vapour, acids, etc. For example, pink velvet coating on iron, black staining on silver, etc.
(b) Odor of fats।
Answer:- When foods containing oil or fat are stored for a long time, the oil or fat in such foods is oxidized in the air and causes them to smell bad and taste bad. This is called fat malodour. For example, if a little butter is left at room temperature for a long time, it melts and gives off a bad smell।
Editing By:- Lipi Medhi
