CHM 102 Leave a Comment / By Hassan Egbetunde / July 9, 2023 Welcome to your CHM 102 The pH of a solution of a salt of weak base and strong acid is....... Greater than 7 (b) (c) (d) Less than 7 Equal to 7 Equal to zero A weak base becomes weaker in the presence of its salt. This statement is… False True Cannot be predicted None Which of the following statements associated with electrochemical cells is incorrect? the function of a salt bridge in an electrochemical cell is to complete the circuit cell potential is the potential difference in a voltaic cell a Bronsted-Lowry acid-base reaction can be the basis of the net reaction in a chemical cell a half-reaction corresponds to one electrode in a voltaic cell Which of the following statements associated with batteries is incorrect? in a dry cell, the reaction Zn → Zn2+ continues to occur even when the battery is not being used secondary batteries are rechargeable the cell reaction in a primary battery is not reversible electrodes with greater surface area give a greater potential What is indicated when a chemical cell’s voltage (E°) has dropped to zero? the concentration of the reactants has increased (b) (c) (d) the concentration of the products has decreased the cell reaction has reached equilibrium the cell reaction has completely stopped What occurs when an atom is oxidized in a chemical reaction? a loss of electrons and a decrease in oxidation number a loss of electrons and an increase in oxidation number a gain of electrons and a decrease in oxidation number a gain of electrons and an increase in oxidation number In the lead storage battery a reversible reaction can occur to recharge the battery lead is oxidized to create a flow of electrons lead forms the cathode when it is being reduced all of the above Which of the following is FALSE regarding the salt bridge used in voltaic cells? The salt bridge _____. allows for the two half-cells to be kept separated maintains the electrical neutrality in each half cell allows mixing of the two electrode solutions is made of a medium through which ions can slowly pass The salt bridge in the electrochemical cell serves to increase the rate at which equilibrium is attained increase the voltage of the cell maintain electrical neutrality increase the oxidation/reduction rate Which of the following statements associated with corrosion is incorrect? iron corrodes more readily than aluminum because iron is more active than aluminium cathodic protection prevents corrosion by using a sacrificial anode a corroding metal has both anodic and cathodic areas corrosion involves both oxidation and reduction Which metal is used as a coating on steel to limit corrosion? Pb Fe Al Zn A system that can transfer neither matter nor energy to and from its surroundings is called Open system Isolated system Closed system Homogeneous system At a constant temperature, the pressure of a gas is given as one atmospheric pressure and 5 liters. When the atmospheric pressure is increased to 2 atm, then what is the volume of the gas? 1L 5L 10L 2.5L What is the shape of the graph that is drawn between pressure and volume? A straight line Circular Parabola Hyperbola What is the name of the graph that is drawn, when the temperature is kept constant? Isotherms Isobars Isochoric Isochoric and Isobars The efficiency of heat engine is maximum when temperatures of source and sink are maximum temperatures of source and sink are minimum temperature of source is minimum and that of sink is maximum temperature of source is maximum and that of sink is minimum The Gibb’s Helmholtz equation is applicable to all processes, chemical or physical all process, chemical or physical but in a closed system all chemical processes in a closed system all physical processes in a closed system The second law of thermodynamics may be stated as it is impossible to take heat from a hotter reservoir and convert it completely into work by a cyclic process without transferring a part of heat to a cooler reservoir. it is impossible to transfer heat from a body at a lower temperature to one at higher temperature the efficiency of heat engine is always less than 1 all of the above Which of the following is true for a cyclic process? ∆E=0 ∆E=q-w q=w all of these Entropy is a measure of _______ of the molecules of the system. Concentration Velocity Zig – zag motion Randomness or disorder. Which of the following is true about the criteria of spontaneity? a spontaneous change is unidirectional a spontaneous change to occur, time is no factor once a system is in equilibrium, a spontaneous change is inevitable all of the above. The tendency of a process to occur naturally is called momentum of the reaction spontaneity of the reaction equilibrium of the reaction Rate of the reaction. The entropy of a pure crystal is zero at absolute zero temperature. This is statement of First law of thermodynamic Second law of thermodynamic Third law of thermodynamic None of the above The change in free energy is a measure of ….. Net work done Net change in entropy Net change in enthalpy None of the above Which of these is not a state function ? Free energy Work function Entropy Work done. What current strength in amperes will be required to liberate 10 g of iodine from potassium iodide solution in one hour? 2.11 A 3.5A 4 A 5.4 A . To study the rate of a reaction, it is necessary to identify the reactants know the relative amounts of reactants used know the overall chemical equation for the reaction all of the above are necessary The half-life of a first-order process depends on the reactant concentration raised to the first power is inversely proportional to the square of the reactant concentration is inversely proportional to the reactant concentration is totally independent of the reactant concentration The reaction, 2NO(g) →N2(g) + O2(g), proceeds in a single elementary step. This reaction is thus the molecularity cannot be determined from the given information termolecular bimolecular unimolecular Why is a minimum energy needed for an effective collision? energy is needed to break bonds energy is needed to orient the particles correctly a minimum energy is needed, so that the particles will collide many times per second enough energy is needed to give off heat in a reaction According to chemical kinetic theory, a reaction can occur if the reactants collide with the proper orientation if the reactants possess sufficient energy of collision if the reactants are able to form a correct transition state All of the above For the hypothetical gas-phase reaction 3A(g) → 2B(g), the number of moles of A present at 25 min is found to be 0.022. If the initial number of moles of A and B were 0.050 mol and 0.00 mol, respectively, how much B is present at 25 min? 0.012 mol 0.019 mol 0.016 mol 0.024 mol Which of the following does NOT affect the rate of a chemical reaction Enthalpy of the reaction Temperature Surface area Concentration. Which statement is not correct regarding the function of a catalyst? it affects the rate of a chemical reaction it lowers the energy of the product, causing the reaction to be more exothermic it changes the mechanism of a reaction it lowers the activation energy. For any chemical reaction at equilibrium, the rate of the forward reaction is less than the rate of the reverse reaction greater than the rate of the reverse reaction equal to the rate of the reverse reaction unrelated to the rate of the reverse reaction A reaction requires the presence of a strip of metal in the reaction vessel, when the reactants are gases. This is an example of what kind of catalysis?. Homogeneous Heterogeneous Equilibrium Reversible A catalyst becomes ineffective by the catalytic poison because it combines chemically with one of the reactants it combines chemically with the catalyst it absorbs reactant molecules it is preferentially adsorbed on the catalyst. Enzymes are…… Finely divided metals Transition metal ions auto – catalysts Protein In the synthesis of ammonia by Haber’s process, the substance which acts as catalytic poison is… Platinum iron AS2O3 H2S In intermediate compound formation theory of catalysis, the intermediate complex formed has lesser activation energy than uncatalysed complex more activation energy than uncatalysed complex lesser kinetic energy than the reactants lesser kinetic energy than the products Hydrolysis of ester is an example of … Pseudo first order kinetic Pseudo second order kinetic Pseudo third order kinetic Zero order kinetic In the electrolysis of aqueous NaCl, how many liters of Cl2 gas (at STP) were generated by a current of 7.50 A for a period of 100 minutes? 5.22 L 6.25 L 12.53 L 3 .35 L When electricity is passed through acidulated water, 224 ml of hydrogen gas at STP is collected at the cathode in 965 sec. The current passed in ampere is….? 2 A 3 A 5 A 1 A. Which of these is a weak electrolyte ? CH3COOH H2SO4 NaOH HNO3. The electrical conductivity of an electrolyte depends upon. the number of ions present in the solution the number of ions present in the electrolyte the number of molecules present in the electrolyte. the number of molecules of the solvent. At a constant temperature, the pressure of a gas is given as one atmospheric pressure and 5 liters. When the atmospheric pressure is increased to 2 atm, then what is the volume of the gas? 2.5L 1L 2L 5L What is the name of the graph that is drawn, when the temperature is kept constant? Isotherms Isobars Isochoric Isochoric and Isobars. There is a balloon filled with a gas at 26-degree centigrade and has a volume of about 2 liters when the balloon is taken to a place which is at 39-degree centigrade, what would be the volume of the gas that is inside the balloon? 2L 3L 4L 5L At 22 degree Celsius a gas consists of pressure 1.1 bars then what is the temperature when the gas consists a pressure of 2.2 bars? 11 12 44 55 Which of the following is a wrong statement about the gas laws? Breathing illustrates Boyle’s law Charles’ law illustrates that the volume of gas expands when temperature becomes higher Avogadro’s law illustrates that the volume of gas is proportional to its mole number or say its quantity or amount. All of the above are correct statements When 6.0 mol of oxygen are confined in a 36-L vessel at 196oC, the pressure is 8 atm. What is the new pressure for oxygen expands at constant temperature to fill 48 L? 6 atm 8 atm 7 atm 14 atm A gas sample of argon, maintained at constant temperature, occupies a volume of 500 L at 4.00 atm. What is the new volume if the pressure were charged to 8 atm? 500L 600L 250L 65.6L What is the resulting temperature of the gas if 200 mL of a gas sample at 27oC expands to 500 mL? 750K 477 oC 890.60 oF All of the above A sample of hydrogen gas in a closed container has a temperature of 37 oC and a pressure of 2 atm. What will be the pressure if the sample is heated to 127 oC? 2.58 atm 3.47 atm 5.21 atm 6.77 atm A sample of gas has a volume of 0.600 L at a temperature of 30 oC and a pressure of 0.8 atm. What is the number of moles in this sample. 0.2 0.02 14.4 145.4 A gas has a density of 3.84 g/L at a pressure of 3.50 atm and a temperature of 37 oC. What is the molar mass (g/mol) of this gas? 27.89 0.102 497.28 As a solid is heated, its temperature increases from 27 oC to 57 oC, remains at 57 oC for 5 minutes, and then increases to beyond 77 oC. What is the melting point of this solid? 27 oC 57 oC 77 oC 30 oC Which of the following definition is wrong? The temperature at which a liquid boils at 1 atm is called normal boiling point. The temperature at which a liquid freezes is called freezing point. The melting point and freezing point for a substance are actually the same. None of the above is wrong. Boiling point increases with increasing molar mass. However, the one with hydrogen bonding will have higher boiling point, and that more hydrogen bonds the greater the boiling point. Which is correct for the increasing order of boiling point? H2 < N2 < O2 < F2 < NH3 < H2O H2 > N2 > O2 > F2 > NH3 > H2O N2 < H2O < O2 < H2 < F2 < NH3 N2 > H2O > O2 > H2 > F2 > NH3 The density of chlorine gas at STP, in grams per liter, is approximately: 3.2 4.5 7.5 5.5 What pressure (in atm) would be exerted by 76 g of fluorine gas in a 1.50 liter vessel at -37 oC? 26 atm 27 atm 28 atm 29atm Which of the following statements is false? The properties of N2(g) will deviate more from ideality at -100 oC than at 100 oC. Van der Waal's equation corrects for the non-ideality of real gases. Molecules of CH4(g) at high pressures and low temperatures have no attractive forces between each other. Molecules of an ideal gas are assumed to have no significant volume. For a gas, which pair of variables are inversely proportional to each other (if all other conditions remain constant)?. P, T P, V V, T n, V A mixture of 0.50 mol H2(g) and 0.50 mol N2(g) is introduced into a 15.0 liter container having a pinhole leak at 30 oC. After a period of time, which of the following is true? The partial pressure of H2 exceeds that of N2 in the container. The partial pressure of N2 exceeds that of H2 in the container. The partial pressures of the two gases remain equal. The partial pressures of both gases increase above their initial values. The number of phase lines that will be observed for the phase diagram of Sulphur is ….? 3 4 7 6 The maximum number of phases that can be simultaneously in equilibrium for a one component system is … 1 2 3 4 At equilibrium the total Gibb’s free energy for all phases is Minimum Maximum Infinity Zero The chemical potential of a species is: Different in all phases at chemical equilibrium Same in all phases at chemical equilibrium Different in all phases at physical equilibrium Same In all phases at equilibrium What is the phase equilibrium ratio? Ratio of heat of species in two phases at equilibrium Ratio of temperature of species in two phases at equilibrium Ratio of mole fractions of species in two phases at equilibrium Ratio of equilibrium concentration of species in two phases at equilibrium. How is the distribution among two or more phases at equilibrium determined by? Application of entropy Application of Newton’s laws of motion Application of Gibbs free energy Application of force The chemical potential of a species is: Different in all phases at chemical equilibrium Same in all phases at chemical equilibrium Different in all phases at physical equilibrium Same In all phases at equilibrium For a liquid-liquid case, what is phase equilibrium ratio? Ratio of mole fractions of species in two phases at equilibrium Ratio of distribution or partition coefficient Ratio of equilibrium constant Ratio of heat of supply Which of the following is regarded as the ‘repeatable entity’ of a 3D crystal structure? Unit cell Lattice Crystal Unit Lattice What is the coordination number of a body-centered unit cell? 8 12 7 5 A solution is found to contain 0.63 g of nitric acid per 100 ml of the solution. If the acid is completely dissociated, calculate the pH of the solution. 1 2 3 4 Given the dissociation constant of acetic acid at 25°C as 1.8 × 10–5, calculate the pH of a solution containing 0.185 g mol acetic acid and 3.015 g mol sodium acetate per litre. 5.96 4.89 3.75 6.35 In zero order reaction kinetics, rate constant is equal to the rate of reaction at all concentration. ABSOLUTELY TRUE ABSOLUTELY FALSE TRUE FALSE. In a chemical reaction, as the temperature increases; the reaction rate … decreases Increases Remains the same Reduces The half-life of a substance in a first order reaction is 15 minutes. Calculate the rate constant ? 4.62 x 10-2 min-1 2.62 x 10-3 min-1 1.35 x 10-1 min-1 2.53 x 10-2 min-1. A reaction in which all reactants are in the same phase with catalyst is called Homogenous Heterogenous Radical Uniradical Species that are formed in one step of reaction mechanism and used up in another step are called… Catalysts Intermediates Inhibitors activated complexes. In a reaction, the initial concentration of the reactant is 2.34 M. The equilibrium mixture contains 1.12 M of the reactant. Equilibrium was achieved in 523 sec. What is the average rate of the reaction? 2.33 x 10-3 mol dm-3 Sec-1 1.33 x 10-3 mol dm-3 Sec-1 5.33 x 10-3 mol dm-3 Sec-1 5.73 x 10-3 mol dm-3 Sec-1. Species that are formed in one step of reaction mechanism and used up in another step are called… Catalysts Intermediates Inhibitors activated complexes. In a second-order reaction the rate constant is 4.0 × 10–4 M–1 s–1. What will be the concentration of reactant after 10 min if the initial concentration is 0.800 M? 0.671 M 1.49 M 2.33 M 3.17 M The thermal decomposition of N2O5 (g) to form NO2 (g) and O2 (g) is a first-order reaction. The rate constant for the reaction is 5.1 × 10–4 s–1 at 318 K. What is the half-life of this process? 1.4 x 103 S 2.3 x 102 S 3.5 x 104 S 4.4 x 102 S The half-life of radioactive sodium is 15 hours. How many hours would it take for a 64 g sample to decay to one-eighth of its original concentration? 45 15 33 52 A first order reaction requires 8.96 months for the concentration of reactant to be reduced to 25.0% of its original value. What is the half-life of the reaction? 4.48 months 3.55 months 8 months 8.54 months The rate constant of a reaction is 1.2 × 10–3 sec–1 at 303 K. Calculate the rate constant at 313 K, if the activation energy for the reaction is 44.12 kJ mol–1 1.47 x 10-3 2.57 x 10-4 4.42 x 10-4 1.17 x 10-3 A first order reaction is 15% complete in 20 minutes. How long will it take to be 60% complete? 112.79 mins 115.56 mins 112.33 mins 120.35 mins The quantity k in a rate law expression is….............. independent of concentration independent of temperature independent of pressure Arrhenius constant The phenomenon of lowering of temperature when a gas is made to expand adiabatically from a region of high pressure into a region of low pressure is known as……........ First Law of thermodynamics Second Law of thermodynamics Le Chatelier’s principle Joule Thomson effect An isochoric process takes place at constant…........ Temperature Pressure Concentration Volume For an adiabatic process, according to first law of thermodynamics, E = -W E = +W E = 0 E = q – W Which of the following properties is not a function of state? Concentration Internal energy Entropy Enthalpy A system absorbs 100 kJ heat and performs 50 kJ work on the surroundings. The increase in internal energy of the system is….? 50 kJ 100kJ 150 kJ 200 kJ The dispersal of a precipitated material into colloidal solution by the action of an electrolyte in solution is called........ Coagulation Dialysis Peptization Ultra-filtration An emulsion is a colloidal solution of a _______ dispersed in another liquid Solid Liquid Gas When HCl gas is passed through a saturated solution of NaCl, the solubility of NaCl will increase will remain the same will decrease will become zero The aqueous solution of salt of a weak acid and strong base will always be…...... Acidic Alkaline Neutral None The degree of hydrolysis of a salt is that fraction of it which undergoes _______ when equilibrium is established....... Dissociation Racemization Saponification Hydrolysis Time's upTime is Up!
