Chemistry Exam Past Paper 2018/19 PDF

## Review Chemistry Exam - 2018/19 **Chemistry I // Sept.-Dec. 2018** **Ine Montgomery Eggja // Year I** 1. Which one of the following orbitals is filled with electron in the ground state hydrogen atom? * p orbital 2. Which process is an oxidation? * Zn+ 2e = ZN * Na = Na+ + e-...

## Review Chemistry Exam - 2018/19 **Chemistry I // Sept.-Dec. 2018** **Ine Montgomery Eggja // Year I** 1. Which one of the following orbitals is filled with electron in the ground state hydrogen atom? * p orbital 2. Which process is an oxidation? * Zn+ 2e = ZN * Na = Na+ + e- * H₂= 2H * Mg = Mg+ 2e- * NaCl + AgNO3 = AgCl + NaNO3 3. What is the maximum number of electrons on an L shell? * 8 4. Which one is a primary bond type? * Ionic bonds, covalent bonds, and metallic bonds are primary bonds 5. Brönsted bases are... * Proton acceptors * Brönsted acids are proton donors * Lewis acids are electron-pair acceptors * Lewis bases are electron-pair donors 6. Solution A has a pH = 1, and solution B has a pH = 2. This means the concentration of H+ ions is... * 10 times higher in solution A than solution B 7. Define "boiling point" * The temperature at which a liquid boils and turns into gas. The boiling point temperature may vary, depending on the element. Vapour pressure of liquid = external pressure. 8. Define the density of a solution. What is the unit of density? Is it an extensive or an intensive property? * Density = m/V = g/dm³ * Density is an intensive property. It is the measure of the quantity of some physical property (mass) per unit length, area, or volume. Mass density is a measure of a mass of the substance per unit volume. 9. Define the Gibbs free energy with formula! * ΔG = ΔH – TΔS, where G = Gibbs free energy, H = enthalpy, T= temperature (K), S = entropy. Gibbs free energy is all the energy available to do useful work. 10. What is micelle? Write an example for a material that builds up micelle. * A micelle is an aggregate of surfactant molecules dispersed in a liquid colloid. A typical micelle in an aqueous solution forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent, and the hydrophobic tail regions in the micelle centre. Ex. Soap 11. What does "ligand" mean in complexometry? What are the common properties of ligands? Write two examples for ligands. * A ligand is an ion or molecule attached to a metal atom by coordinate bonding. Examples for ligands are: NH₃, Cl, H₂O 12. Write the ideal gas law, and name the symbols * PV=nRT P-pressure, V = volume, n = # of moles, R= gas constant, T= temperature 13. What does the "delocalized" bond mean? Show an ion or a molecule contains delocalized bond! * Electron density is spread out through the whole atom, rather than being in one fixed position 14. What is the difference between an exothermic and and an endothermic reaction? * An exothermic reaction is a chemical reaction that releases energy through light or heat. * An endothermic reaction absorbs energy from its surroundings. 15. What does "isotope" mean? * Isotopes are molecules who have the same atomic number, but different mass number. Ex. ¹²C, ¹³C, ¹⁴C 16. What does the "colligative properties" mean? Give two examples * Properties that depend on the concentration of solute molecules or ions. * Ex.: Osmotic pressure, boiling point elevation, freezing point depression. 17. What is the definition of ionization energy? How does it change in a column of the periodic table? * Willingness of an atom to become an ion. The further right - higher ionization energy. * It is the amount of energy required to completely remove the most loosely held electron from the gaseous atom. Units: J, eV, or J/mol 18. What is the difference between the galvanic cells and electrolysis? * Electrolysis charges a battery, while galvanic cells use energy. 19. Define the bond order! Calculate it for O₂ molecule? * The half of the difference between the number of bonding, and antibonding electrons in the given molecule For O₂ (10-6)/2=2 20. Small amount of arsenic (3) ions can be detected by.. * Griess-Ilosvay reagent * Nessler reagent * Bettendorf reagent 21. Which one of the following substance can make hydrogen bond? * NH₃ 22. Which one of the following substances does only exist? * K₂Cl 23. Which of the following statements about hydrogen halides (HX) is correct * From HF to HI the ionic character and energy of H-X bond increases 24. Which compound is NOT solid in standard conditions * Br₂ * I₂ 25. Write the balanced reactions equations * Aluminium + hydrochloric acid: Al + HCl → AlCl₃ + H₂ * Silver chloride + ammonia: AgCl + NH₃ → [Ag(NH₃)₂]Cl * Calcium carbonate + carbon dioxide + water: CaCO₃ + CO2 + H2O → Ca(HCO3)2 * Chlorine + water: Cl₂ + H₂O → HCl + HOCl * Copper + nitric acid: Cu + HNO3 → Cu(NO3)2 + NO2 + H2O 26. Name the following materials * K₃PO₄ = tripotassium phosphate * HNO₂ = nitric acid * NH₃ = Ammonia 27. Which is NOT a colloidal system? * sodium chloride solution 28. Which of the statement is NOT a postulate of the kinetic theory of gases? * The average kinetic energy of the molecules of a gas depends upon the pH 29. Give example for a buffer system! How do you calculate the OH concentration in an alkaline buffer system? What is the importance of buffers? * A solution which resists changes in pH when a small amount of an acid or base (H+ or OH-) is added to the solution. A buffer system consists of a weak acid and its conjugated base. * Ex. NH₃+H₂O→ NH₄⁺ + OH * Ex.: CH3COOH + H₂O → CH3COO- + H₂O+ 30. How does the catalyst increase the reaction rate? Which material can catalyze the decomposition of H₂O₂? * It opens a new path by which the reaction can take place, and lowers the energy of activation (Ea) 31. What are lewis acids and lewis bases? Write definition and example of each! * Lewis acids are electron pair acceptors * Lewis bases: Are electron pair donors H, H₂O, NH₃, HO- 32. Write the solubility product for silver(1) chloride! * Ksp=[Ag+]×[Cl-] 33. How can the electromotive force (standard cell potential) be calculated? Write the formula! What is the unit of emf? * E°cell = E°cathode (reduction) - E'anode (oxidation) * Volt (V) 34. What does Hund's rule say? → Hund's rule of maximum multiplicity * Electrons build up the atomic orbitals of a subshell with the maximum number of parallel spins. 35. Write the formula of three alkaline substances * Sodium Hydroxide: NaOH * Potassium Hydroxide: KOH * Calsium Hydroxide Ca(OH)2 36. How can you detect (reaction eq. and observation) in aqueous solution the * Bromide ions * Sulfide ions * Iron(3)ions 37. Name the following materials * H₂SO₄ Sulfuric Acid * AgNO3 Silver Nitrate * NH4 Hydrazine 38. What is autocatalysis? * One of the products formed acts as a catalyst and that reacts with another product in order to continue the reaction. When the product itself can catalyse the reaction 39. Write the balanced reaction equations * Zn + HCl = ZnCl2 + H₂ * CaCO3 (heated) = CO2(g) + CaO (s) * Na + H₂O = NaOH + H₂ * H₂S + O₂ = SO2 +H₂O * NH3 + HNO3 → NH₄NO₃ 40. What is Hess' law? * The enthalpy Change of a reaction is the same, regardless of the pathway whether it's completed in one or several steps 41. What is the difference between a strong and a weak acid? Give examples for both. * Main difference is degree of dissociation. Strong acids totally ionize, releasing all the hydrogen ions. Weak acids only partially ionize. * Strong acids: HNO3, HCl * Weak Acid CH3COOH 42. What are the three laws of thermodynamics? * In any change that occurs in nature, the total energy of the universe remains constant. The energy may be converted from one to another. * The entropy of an isolated system never decreases, because isolated systems always decay toward thermodynamic equilibrium: a state with maximum entropy. * The entropy of a perfect crystal, at absolute 0K, is exactly equal to zero. 43. What is the Arrhenius-Equation? Name the symbols. * k = Ae^(-Ea/RT) k = rate constant, Ea = energy of activation (J/mol); T= abs. temperature (Kelvin) A = constant (characteristic of the given reaction); R = 8.314J/mol x K → universal gas constant 44. Name three oxidizing agents * Solids: Ex potassium permanganate * Liquids: Ex. hydrogen peroxide, bromine * Gases: Oxygen, ozone, chlorine 45. What is Henry's law? * C = KPgas The sowbility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. 46. What are multidentate ligands? * Multidentate ligands are ligands with more than one donor atom that are capable of occupying coordination position of a metal ion from cyclic (5-, or 6-membered ring) complexes called chelates 47. What is the difference between strong and weak bases? Give examples for both * The main difference between strong and weak bases, is the degree of ionization. * A strong base is a compound that will completely ionize into metal and hydroxide ions when in solution. Conversely, a weak base only partially ionizes to metal + hydroxide ions in solution. * Strong base pH = 10-14, KOH, Ba(OH)2, NaOH * Weak base: pH = 7.3-10 48. What is Boyle's law? * PV=K * PV₁=P₂V₂ * Experimental gas law that describes how the pressure of a gas tends to decrease as the volume increases ↑. It is the relationship between pressure and volume. Ex.: change in diameter of a tube. P= pressure of the gas, V= volume of the gas, K = constant 49. What are Brønsted acids and bases? Give an example for each * Bronsted Acids: Proton donors / H+ donors * Brønsted Bases Proton acceptors / H+ acceptors 50. Define freezing point * The temperature at which a liquid solidifies when solid and liquid are in equilibrium 51. What is an Azeotrope? * A mixture of two or more liquids whose proportions cannot be altered by simple destillation 52. What is. Charle's law? * Experimental gas law that describes: The relationship between VOLUME and TEMPERATURE It describes how GAS tends to expand when HEATED. "When the pressure is constant, the Kelvin temperature and the volume will be directly related:" 53. Define half life * T'/2= the amount of time required for a quantity to fall to half its value as measured at the beginning of the time period. 54. What is heavy water? * Deterium oxide, D₂O 55. What is the Tyndall-effect? * Scattering light on colloid size particles. 56. Define dialysis * The process of removing waste products and excess fluid from the body 57. What are oxidizing and reducing agents? * An oxidizing agent gains electrons, and is reduced in a chemical reaction. A reducing agent is known as an electron donor it is oxidized, because it loses electrons in the redox reaction. 58. What is a colloid? * A substance microscopically dispersed throughout another substanse (like fat in milk) Particles that are invisible in an optical microscope about 1-Soonm in size. 59. What is Avogadro's number, and what does it mean? * 6.022x10²³ mol. It is the number of particles per mole. 60. Write the balanced equation for the following * Dihydrogen sulfide + oxygen: H₂S + O₂ → SO₂ + H₂O * Zinc + hydrochloric acid: Zn + 2HCl → ZnCl₂ + H₂ * Calcium carbonate heated: CaCO₃ (heat) → CO₂(g) + CaO (s) * Sodium + water: 2Na + 2H₂O → 2NaOH + H₂ * Ammonia + nitric acid: NH₃ + HNO₃ → NH₄NO₃ 61. What is the unit of the mass concentration of a given solution? * g/dm³ 62. What are the conjugated acid-, and base pair of water? * Acid H₂O * Base: OH⁻ 63. What is the Arrhenius concept of acids and bases? * ACIDS Produce H+ in water * BASES Produce OH- in water 64. How much is 1 mol? * 1 mole measures the number of particles in a specific substance. * 1 mol = 6.022x10²³ atoms or molecules 65. What is the difference between extensive and intensive properties? Give examples for each * Extensive properties (ex. mass and volume) depend on the amount being measured. * Intensive properties (ex. density and colour) do not depend on the amount of substance. 66. Draw a metal chelate complex! * A diagram would need to be drawn here 67. Give the formulas of three oxyacids of phosphorus * H₃PO₂ * H₃PO₃ * H₃PO₄ 68. What are hydrogen halides? * Colourless gases at 25°C. Well soluable in water, forming azeotropic mixtures. 69. Draw the colloidal incoherent system on basis of structure * A diagram would need to be drawn here 70. Write the solubility product for iron (III) hydroxide * Ksp = [Fe³⁺] [OH⁻]³ 71. Classify the colloidal incoherent system on the basis of structure * Same as q. 69. 72. What is a colloidal system? Give an example * Colloids are formed when one substance is dispersed through another, but does not combine to form a solution. * Ex egg white foam: Air bubbles (disperse phase) are trapped in the egg white (continous phase), resulting in foam 73. What is emulsion & suspension? Give an example * → ex. oil and water * Emulsion: A mixture of two or more liquids that are normally immiscible * Suspension: A heterogenous mixture in which the solute particles do not dissolve, but get suspended throughout the bulk of the solvent, left floating around freely in the medium → salt water 74. How does the boiling point of a liquid depend on the external pressure? Is the boiling point higher or lower on Mount Everest? * When the vapour temperature is equal to the external temperature, surrounding the liquid, we reach the boiling point. The boiling point is lower on Mount Everest since the pressure is lower 75. What is the difference between the ionization energy and the electron affinity? * Electron affinity gives the amount of energy released when an atom gains an electron * lonization energy is the amount of energy required to remove an electron from an atom 76. Write the formula for Arrhenius equation and name the symbols * K = Ae^(-Ea/(RT)) * K = rate constant, A= total # of collisions (leading to a reaction or not), e^(-Ea/(RT)) = the probability that any given collision will result in a reaction R = universal gas constant, T. absolute temperature 77. Which one is a p orbital? * A diagram would need to be drawn here 78. Molecular orbitals... * are the regions in the nucleus where the electron density is high * results from the interaction of atomic orbitals of the bonding atoms * have always lower energies than atomic orbitals 79. Which of the following substances has the most polar chemical bond? * HCl 80. Which particles build up the nucleus of helium? * protons and neutrons 81. Potassium chloride is dissolved in water. The solution becomes... * neutral as this salt does not react with water 82. Solution A has a pH = 1, and solution B has a pH = 3. This means the concentration of H+ ions is... * 100 times higher in solution A than in solution B 83. What is the total concentration of ions in a 0.1 mol/dm³ of potassium chloride solution? * 0.2 mol/dm³ 84. What is the unit of the amount concentration of a given compound? * mol/dm³ 85. Define the following... * Covalent bond: A chemical bond that involves the sharing of electron pairs between atoms * Oxidation: The loss of an electron * Half time of a chemical reaction: It's the time required for the reactant concentration to decrease to half of it's initial valve. It is a constant that is related to the rate constant for the reaction * Critical temperature: The temperature above which a gas cannot be liquified, regardless of pressure applied * Electromotive force: A difference in potential that tends to give rise to an electric current * Coagulation: Physical reaction. The action or process of a liquid, especially blood, change to a solid or semi-solid state. Coagulants are added to water to bring the nonsettling particles into larger, heavier masses of solids * Isolated system (in thermodynamics): The entropy of an isolated system never decreases, because isolated systems always decay toward thermodynamic equilibrium: a state with maximum entropy. * (Brönsted) acid: Proton donor 86. How does an "acid-base" indicator work? Give an example for this! Also write the colors for the chosen indicator * Acid-base indicators are substances that change color with pH. They are usually weak acids or bases which, when dissolved in water, dissociate slightly and form ions. * Ex. Hln 87. What is "osmotic pressure"? Write the formula and name the symbols * The pressure that needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane 88. What does the Pauli exclusion principle say? * It is impossible for two electrons of a poly-electron atom to have the same values for the four quantum numbers 89. Give a definition for "solubility" * The ability or willingness for a given substance, the solute, to dissolve in a solvent. 90. What is the conjugated acid-, and base of hydrogen carbonate, HCO, anion? * conj. acid: HCO3- * conj. base: CO3²- 91. Define the Le Chatlier-Braum principle * A chemical equilibrium reacts to change (stress) by a shift in the equilibrium to counteract the imposed stress. Ex. temp ↑, pressure ↑, volume ↑ * → A new equilibrium state will be established 92. Write the formula for the following: * Heat Capacity: C = q / ΔT where q= the quantity of heat transferred and is the ΔT temperature change. * Osmosis: πC = CXRXT * Rate Law: V= kx [A]×[B]×[C] 93. How can we calculate the standard reaction enthalpies? * Hrxn = Σn ΔHi (products) - ΣmΔHi (reactants) 94. Write the three different effects/things that can stabilize a colloid solution * Answers vary, but might include: the presence of an electric charge, Brownian motion, the presence of a stabilizing agent. 95. Write the ideal gas law and name the symbols * [PV=nRT * P-pressure, V- volume, n- number of moles, R- gas constant, T. temperature (K) 96. What does "C" mean? What is the difference between ¹²C and ¹³C? Which can be found in the nature in greater amount? * ¹²C is carbon and ¹³C is the mass number. ¹²C and ¹³C are isotopes and have different mass number, but the same atomic number. * ¹²C is found in nature 97. How does the pressure change if we heat a gas in a closed box? * Higher pressure because the gas expands. 98. How does the pressure change if - because of a dissociation - the amount of gas increases in the same box> * The pressure will increase. 99. What is the definition of ionization energy? How does it change down a group? * Ionization energy is an atom's willingness to become an ion. The more right on the periodic table, the higher the ionization energy. 100. What does Faraday's law say? Write the formula and name the symbols * m=(M*Q)/(z*F) m= mass of substance liberated at an electrode in grams, M. molar mass of the substance, z. charge of the ion (e transferred per ion), Q = the total electric charge passed through, F-Faraday constant (96485 C mol-¹), Quantity of electricity is directly proportional to the chemical change in electrolysis 101. What does "double bond" mean? Write an example for an ion or a molecule which contains double bond * A chemical bond between two chemical elements involving four bonding electrons instead of the usual two. Most common double bond is between two carbon atoms 102. Define bond order. Calculate the bond order of N₂ molecule * Bond order is the relationship between bonding and antibonding particles in a molecule 103. Small amount of nitrate ions can be detected by... * Griess-losavy reagent * Nessler reagent * Bettendorf reagent 104. Which one of the following materials is soluble in water? * potassium chloride 105. Which one of the following substances does only exist? * Na₂Cl₂ 106. Which of the following statements about hydrogen halides (HX) is correct? * From HF to HI the ionic character-, and energy of H - X bond increases 107. Which compound has a strong odor (smell)? * NH₃ 108. Write the balanced reaction equations: * sulfur dioxide + water: SO₂ + H2O → H₂SO₃ * lead hydroxide + sodium hydroxide: Pb(OH)2 + NaOH → Na₂[Pb(OH)4] * calcium hydroxide + carbon dioxide: Ca(OH)2 + CO₂ → CaCO3 + H₂O * chlorine + water: Cl₂ + H2O → HCl + HOCl * sodium + water: 2Na + 2H₂O → 2NaOH + H₂ 109. Write the formula for 3 strong acids * HCl * HNO₃ * H₂SO₄ 110. Name the following materials... * Na₂S₂O₃ - Sodium thiosulfate * K₃PO₄ -tripotassium phosphate * H₂O₂-hydrogen peroxide 111. How can you detect (reaction equation and observation) in aqueous solution the... * silver ions * lead (II) ions * mercury (II) ions 112. What is the building up (Aufbau) principle? * Subshells are built in an order as the subshell energy increases 113. What is a Galvanic Cell? * An electrochemical cell that uses the transfer of electrons in redox reactions to supply an electric current 114. What is electrolysis? * A process by which electric current is passed through a substance to effect a chemical change 115. What is the difference between a heterogenous and a homogenous equilibrium? * Homogenous: The substances are in the same phase. Ex. H₂ + I₂ = 2HI * Heterogenous: The substances are in different phases. Ex. NH₃ + HCl = NH4Cl 116. Define the following: * Adhesion: An attraction between molecules of different substances * Cohesion: An attraction between molecules of the same substance * Chromatography: A laboratory technique used to separate mixtures of molecules * Retention Time: Amount of time a compound spends in stationary phase * Hybridization: The mixing of at least two non-equivalent atomic orbitals * Evaporation: Liquid to gas * Condensation: Gas to liquid * Complex Ions: Transition metals with ammonia, hydroxide, cyanide or thiocynate form * Coulomb's Law: Gives the electric force between two charges * Oxoacids: Acids that contain hydrogen, oxygen, and another element 117. What is Archimedes Principle? * Weight lost by an object immersed in a fluid is equal to the weight of the fluid displaced 118. What is a buffer solution? * A solution which resists change in pH when small quantities of an acid or an alkali are added to it 119. Rusting or loss of iron * Fe(s) → Fe²+ (aq) + 2e [anodic region; oxidation] * O2(g) + 4H+(aq) + 4e- → 2H₂O (l) [cathodic region; reduction] 120. What is the difference between anions and cations? * Anions: Ions with a net negative charge. Ex. Hydroxide anion OH⁻, Oxide anion O²⁻ * Cations: Ions with a net positive charge. Ex. Silver Ag⁺, Ammonium NH₄⁺ 121. What is the retention factor? * Rf= (distance of the spot of a component from the baseline) / (distance of the solvent front from the baseline) 122. Peak Area is... * Proportional to the relative amount of the separated components (quantative analysis) 123. What are indicators? * Organic compounds that change color in a solution as the pH changes 124. Carboxylic Acid * (COOH), CH3COOH, HCOOH, OHCOOH 125. Classify the colloidal dispersion based on the physical states of the internal and external phase * Depending on the physical state of dispersed phase and dispersion medium → whether or not these are solids, liquids or gases, eight colloidal systems are possible. 126. What is the difference between internal and external phases? Give examples for each * Internal Phase: It is the component present in small proportion. Ex. colloidal solution of silver in water as silver acts as a dispersed phase * External Phase: It is the component generally present in excess. Ex. colloidal saution of silver in water as water acts as a dispersion medium 127. What is catalytic poison? * inhibitor * A substance that inhibits the activity of catalyst by blocking its "active site". 128. What is the law of mass action? * K = ([C] x [D]) / ([A] x [B]) K- equilibrium constant in (mol/dm³)", where n = 0, ±1, ± 2,... * independent on the concentrations * depends on the temperature * [C], [D], [A], [B]- concentrations are in equilibrium state in mol/dm³ * by convention the concentrations of the * products in numerator (right side) * reactants in denominator (left side) 129. What is the critical pressure of gases? * It is the minimum pressure needed to liquify a gas at its critical temperature 130. Define polar covalent bond * Bonding electrons shared unequally between two atoms partial charge on atoms