VVI 5 Marks Easy Chemistry PDF

# Magnetic Property of Solid - What is magnetic property of solid? - Define the terms: - Paramagnetism - Those substances which are weakly attracted by magnetic field is called paramagnetism e.g O₂, Cu²⁺, Fe³⁺, etc - Diamagnetism - Those substances which a...

# Magnetic Property of Solid - What is magnetic property of solid? - Define the terms: - Paramagnetism - Those substances which are weakly attracted by magnetic field is called paramagnetism e.g O₂, Cu²⁺, Fe³⁺, etc - Diamagnetism - Those substances which are repelled by magnetic field is called diamagnetism e.g. C₆H₆, Zn²⁺, Sc³⁺ etc - Ferrimagnetism - Those substances which are strongly attracted by magnetic field as compared to ferromagnetic e.g. Fe₂O₃, MgFe₂O₄, ZnFe₂O₄ etc. - Antiferromagnetism - Antiferromagnetism have domain structure similar to the ferromagnetic substances but their domains are oppositely oriented and cancel out each other's magnetic moment. e.g. MnO. # 1st Order Reaction - Derive an expression for the rate constant of a 1st order reaction. - Integrated rate law for 1st order reaction: - For 1st order reaction: - A → B - t = 0 sec, a = 0 - t = t sec, a = x = a - t x - From rate law, r = KLA¹ - From differential rate law, r = - dA/dt - From above two equations we get: -dA/dt = K[A] - -dA/A = Kat - Integrating on both sides, ∫(1/A)-dA = ∫kat, which gives us: [lnA]_a^at = K[t]₀^t - [lnat - lna] = K[ t - 0] - [lnat - lna] = Kt - Kt = [lnat - lna] - Kt = 2.303log₁₀(a) - 2.303log₁₀(at) - Kt = 2.303(log₁₀(a) - log₁₀(at)) - Kt = 2.303log₁₀(at/a) - Kt = 2.303log₁₀(a/a-x) - K = 2.303/t * log₁₀(a/a-x) # Electrochemical Cell - What is electrochemical cell? Explain the structure of cell and its working. - **Galvanic cell** - A device which converts chemical energy into electrical energy is called galvanic cell - **Constructing** - Anode(-) - Zn rod, 1M ZnSO4, Zn(s) → Zn²⁺(aq) + 2e- (Oxidation half reaction) - Cathode(+) - Cu Rod, 1M CuSO4, Cu²⁺(aq) + 2e- → Cu(s) (Reduction half reaction) - Salt Bridge - AgNO₃/Kcl - **Working** - **Cell reaction** - At Anode:, Zn(s) → Zn²⁺(aq) + 2e-(oxidation), At Cathode: Cu²⁺(aq) + 2e- → Cu(s) (reduction) - **Overall cell reaction** - Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s) # Electrolytic Cell - What is electrolytic cell? Explain the construct and working. - **Electrolytic cell** - A device which converts electrical energy into chemical energy during electrolysis is called electrolytic cell. - **Constructing** - Anode(+) - Cathode(-) - Aquous solution of an electrolyte(CA) - Reduction (anion) - Oxidation (cation) - C → cation, A → anion - **Working** - **At Cathode** - Reduction Reaction, C → C⁺(aq) + e- - **At Anode** - oxidation reduction, A⁺ + e- → A-(aq) # Relative Lowering in Vapour Pressure - What is relative lowering in vapour pressure? Determine the molar mass of non-electrolyte solute by using relative lowering in vapour pressure. - **Relative lowering in vapour pressure** - It is the ratio of lowering in vapour pressure and vapour pressure of pure solvent. - **Relative lowering in vapour pressure** = ΔP/P^o = lowering in vapour pressure/vapour pressure of pure solvent. - **Determination of molar mass of solute** - According to the Raoult's law, relative lowering in vapour pressure is equal to the mole fraction of solute. - **Mathematically** : - ΔP/P^o = x₂ - ΔP/P^o = n₂/(n1 + n2) - If n₂ << n₁ then, ΔP/P^o = n₂/n₁ - ΔP/P^o = (W₂/M₂) / (W₁/M₁ ) - ΔP/P^o = (W₂ x M₁)/(W₁ x M₂) - M₂ = (P^o x W₂ x M₁)/(ΔP x W₁) - Where: - P^o = vapour pressure of a pure solvent - ΔP = lowering in vapour pressure - W₂ = weight of solute - M₁ = molar mass of solvent - W₁ = weight of solvent # Manufacturing of Sulphuric Acids - Explain the manufacturing of sulphuric acids by contact process. - Write the reaction of conc. sulphuric acid with oxalic acid. - **Manufacturing of sulphuric acid** - Sulphuric acid is manufactured by the contact process, which involves three steps: - **Burning of sulphur or sulphide ore in air to generate SO₂** - **Conversion of SO₂ to SO₃ by the reaction with oxygen in the presence of catalyst V₂O₅** - SO₂(g) + O₂ (g) →^V₂O₅ 2SO₃(g) - **Absorption of SO₃ in H₂SO₄ to give oleum** - SO₃(g) + H₂SO₄ → H₂S₂O₇. - Oleum undergoes hydrolysis to give 96-98% pure sulphuric acid - H₂S₂O₇ + H₂O → 2H₂SO₄ - **Reaction of conc. H₂SO₄ with oxalic acid** - conc. H₂SO₄ + (COOH)₂ → CO(g) + CO₂(g) + H₂O # Osmotic Pressure is a Colligative Property - Prove that osmotic pressure is a colligative property. - How molar mass of Non-Electrolyte determined by osmotic pressure? - **Osmotic pressure is a colligative property** - **Mathematically**: π = CRT, π = n/V*RT. - If n ↑ then π ↑. If n ↓ then π ↓. - So we can say that osmotic pressure is a colligative property because it depends upon the number of solute particles. - **Determination of molar mass of non electrolyte** - π= CRT - π = n/V*RT - π = W₂/M₂ * RT/V - M₂ = W₂RT/πV - Where: - M₂ = molar mass of solute - W₂ = weight of solute - R = gas constant - T = temperature - π = osmotic pressure - V = volume # Difference between Osmosis and Diffusion - Write the difference between osmosis and diffusion. - **Difference between osmosis and diffusion:** - | Osmosis | Diffusion | - |---|---| - | The process of osmosis takes place through a semipermeable membrane | For the process of diffusion no semipermeable membrane required | - | Osmosis only occurs in liquid medium | Diffusion can occur in any medium. | - | In osmosis, molecules of solvent move from a region of lower concentration of solution into a region of higher concentration | In diffusion, both solvent and solute move from a region of higher concentration into a region of lower concentration | - | In osmosis only solvent molecules involve | In diffusion, both solvent and solute molecules involve | # Difference between Galvanic Cell and Electrolytic Cell - What are differences between Galvanic cell and electrolytic cell? - **Difference between Galvanic cell and Electrolytic cell** - | Galvanic cell | Electrolytic cell | - |---|---| - | A device which converts chemical energy into electrical energy | A device which converts electrical energy into chemical energy | - | The solutions of the electrolyte are taken in different vessels and a strip of conductor is placed in each solution | Two electrodes are placed in a vessel containing the solution of the electrolyte | - | In this cell, the negative electrode is anode | In this cell, positive electrode is anode | - | In this cell, the positive electrode is cathode | In this cell, the negative electrode is cathode | - | Salt bridge is required in this cell | No salt bridge is required in this cell | # Fuel Cell - What is a fuel cell? Give the electrode reaction of hydrogen-oxygen cell. - **Fuel Cell** - Fuel cell is a galvanic cell which converts directly heat energy obtained from combustion of fuels in the cell into electrical energy. Gases like hydrogen, methane, etc are used as fuel cells. The most successful fuel cell is hydrogen-oxygen fuel cell. - **The reaction takes place in hydrogen-oxygen fuel cell**: - **At Cathode**: O₂(g) + H₂O(l) + 4e^- → 4 OH^-(aq) - **At Anode**: 2H₂(g) + 4 OH^-(aq) → 4H₂O(l) + 4e^- # Activation Energy and Effect of Catalysts - What do you understand by activation energy? What is the effect of catalyst on activation energy and velocity of reaction? - **Activation energy** - The minimum amount of extra energy that is required to convert reactant into product is called activation energy. It is denoted by E_a. - E_a = Threshold energy - Average K.E of reactant molecule. - **Effect of catalyst on activation energy and velocity of reaction:** - **Positive catalyst**: Positive catalyst decreases the activation energy and increases the velocity of reaction. - **Negative catalyst**: Negative catalyst increases the activation energy and decreases the velocity of reaction. # Order of Reaction - Define the order of reaction. How will you know that a reaction is of first order. - **Order of reaction** - It is the sum of powers of concentration of reactants in rate-law expression. - From rate law: r = K[A]^x[B]^y - Order of reaction = x + y - Where, n = x + y, x, y = exponents, n = order of reaction. - It may be fractional, zero and -ve. - It is experimental value. - It is applicable for elementary as well as complex reactions. - If a graph of natural logarithm of reactant concentration versus time is a straight line with a negative slope, then we can say that it's a first order reaction. # Depression in Freezing Point - What is depression in freezing point? How to determine molar mass of non-volatile solute. - **Boiling point** - The temperature at which vapour pressure is equal to atmospheric pressure is called a boiling point. - **Depression in freezing point** - When non-volatile solute is added in volatile solvent then the freezing point of a solution decreases than that of pure solvent is called depression in freezing point. - **Mathematically**: ΔT_f = T_f^o - T_f - Where: ΔT_f = depression in freezing point, T_f^o = freezing point of solvent, T_f = freezing point of solution. - **Determination of molar mass of non-volatile solute**: According to Raoult's law depression in freezing point is directly proportional to the molality of the solution. - **Mathematically**: ΔT_f α m - ΔT_f = K_f m - ΔT_f = K_f x W₂/W₁ in kg * M₂ - M₂ = K_f x W₂/ΔT_f x W₁ in kg - Where: - M₂ = molar mass of solute - K_f = molal depression constant - W₂ = weight of solute - ΔT_f = depression in freezing point - W₁ = weight of solvent # Elevation in Boiling Point - What is elevation in boiling point? How to determine molar mass of non-volatile solute? - **Boiling point** - The temperature at which vapour pressure is equal to atmospheric pressure is called a boiling point. - **Elevation in boiling point** - When non-volatile solute is added in volatile solvent then the boiling point of solution increases then that of boiling point of a pure solvent is called elevation in boiling point. - **Mathematically**: ΔT_b = T_b - T_b^o - Where: ΔT_b = elevation in boiling point, T_b = boiling point of solution, T_b^o = boiling point of solvent. - **Determination of molar mass of non-volatile solute**: According to Raoult's Law elevation in boiling point is directly proportional to the molality of the solution. - **Mathematically**: ΔT_b α m - ΔT_b = K_b m - ΔT_b = K_b x W₂/W₁ in kg x M₂ - M₂ = K_b x W₂/ΔT_b x W₁ in kg - Where: - M₂ = molar mass of non-volatile solute - K_b = molal elevation constant - W₁ = weight of solvent in kg - W₂ = weight of non-volatile solute # Preparation of Ammonia - Write the methods of preparation of ammonia from Haber's process and maintain the condition for maximum yield of ammonia. - Write the reaction of ammonia with: - Cu²⁺(aq) - AgCl - CuSO₄ - **Methods of preparation of ammonia** - On a large scale ammonia is prepared by Haber's process. In this process, nitrogen is treated with hydrogen under high pressure and in the presence of catalyst iron oxide with small amounts of K₂O and Al₂O₃ then the formation of ammonia. - **Reaction**: N₂ + 3H₂ →^{High Pressure, Iron oxide , K₂O and Al₂O₃} 2NH₃ - **Condition for maximum yield of ammonia**: - High Pressure ( 200 atm) - Low Temperature (~ 700 k) - Catalyst iron oxide with small amounts of K₂O and Al₂O₃ - Molybdenum (Mo) used as a promoter. - **Reaction of ammonia**: - **With Cu²⁺(aq)** - Cu²⁺(aq) + NH₃ → [Cu(NH₃)₄]²⁺ (Blue) - **With AgCl** - AgCl(s) + NH₃ → [Ag(NH₃)₂]Cl (Colorless) - **With CuSO₄** - CuSO₄ + NH₃ → [Cu(NH₃)₄]SO₄ (Blue color)