GENERAL CHEMISTRY QUARTER 2 ANSWER SHEET, Study notes of Chemistry

Download GENERAL CHEMISTRY QUARTER 2 ANSWER SHEET and more Study notes Chemistry in PDF only on Docsity!  MODULE 1A; LESSON 1  WHAT’s IN Directions: Recall the concepts of Molecular Geometry, Polarity, Bond Dipole and Dipole Moment. Complete the table by following these instructions. 1. Draw the Lewis Structures of the following molecules with the correct shape around the central atom. 2. Indicate each bond’s polarity by drawing an arrow to represent the bond dipole along each bond. 3. Determine the molecule’s polarity and indicate this with an arrow to represent the dipole. 4. Circle your choice in each box to make the molecule as polar or nonpolar.   ACTIVITY 3: LET’s TEST YOUR UNDERSTANDING! Directions: read and answer each question carefully. 1. (a) Which type of intermolecular attractive force operates between all molecules?  Dispersion forces are present between all molecules, whether they are polar or nonpolar. Larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones. (b) Which type of intermolecular attractive force operates only between polar molecules? - Dipole dipole operates only between polar molecules. This is when two polar molecules get near each other and the positively charged portion of the molecule is attracted to the negatively charged portion of another molecule. (c) Which type of intermolecular attractive force operates only between the hydrogen atom of a polar bond and a nearby small electronegative atom? -   Dipole dipole and in some cases hydrogen bonding operate between the hydrogen atom of a polar bond and a nearby small electronegative atom. 2. (a) What is meant by the polarizability? - Polarizability is defined as the ease with which the electron cloud of an atom or molecule is distorted. (b) Which of the following atoms would you expect to be most polarizable: N,P, s, Sb? Explain - Antimony (Sb) is the most polarizable because its valence electrons are farthest from the nucleus and least tightly held. (c) List the following molecules in order of increasing polarizability: GeCl4, CH4, SiCl4, SiH4 and GeBr4. - Polarizability increases as the number of electrons increases (CH4 < SiH4 < SiCl4 < GeBr4) (d) Arrange the boiling points of the substances in part (c) in increasing order. - CH4, SiH4, SiCl4, GeCl4, GeBr4 3. Which of the following can form hydrogen bonds with water? - Hydrogen bonding between two water (H2O) molecules. Note that the O atom in one molecule is attracted to a H atom in the second molecule. Hydrogen bonding between a water molecule and an ammonia (NH3) molecule. 4. As a metal such as leads melts, what happens to (a) The average kinetic energy to atoms?  The particles move farther apart and potential energy increases. Once a solid completely melts the additional of thermal energy will cause the kinetic energy of the particles to increase again. (b) The average distance between the atoms? Cl2 C C nonpolar NH3 H N H H polar CH3Br H H C Br H CH4 H H C H H nonpolar  The average distance between the atoms decreases. The average distance between the atoms does not change  ACTIVITY 4: Directions: Read and answer each question carefully. 1. (a) Does the diagram best describe a crystalline solid, a liquid, or a gas? (b) Explain. - As I can see in the picture provided, my answer is liquid, because in liquid, the molecules are  still touching but there are some spaces between them 2. List the three states of matter in their order of (a) Increasing molecular disorder and - Gas - Liquid - Solid (b) Increasing intermolecular attraction. - Solid - Liquid - Gas (c) Which state of matter is most easily compressed? - Gas. In gases, the atoms are much more spread out than in solids or liquids, and the atoms collide randomly with one another. A gas will fill any container, but if the container is not sealed, the gas will escape. Gas can be compressed much more easily than a liquid or solid.  MODULE 1B  PRE-TEST 1. B 2. A 3. D 4. D 5. D  ACTIVITY 1: Directions: As part of our review of our previous lessons on intermolecular forces, list the type/s of intermolecular forces the exist between molecules (or basic units) in each of the following species. (a) benzene (C6H6) - LONDON DISPERSION FORCE (b) CH3Cl - DIPOLE-DIPOLE AND LONDON DISPERSION FORCES (c) PF3 - DISPERSION AND DIPOLE-DIPOLE FORCES (d) NaCl - ION-DIPOLE FORCES (e) CS2 - LONDON DISPERSION FORCE  ACTIVITY 2:  POST-TEST 1. B 2. C 3. B 4. B 5. A  MODULE 1C  PRE-TEST 1. B 2. A 3. C 4. C 5. six 6. D 7. E 8. six 9. eight 10. four  ACTIVITY 1 Direction: Examine the images and answer the questions. 1. What are the two general types of solid? - Crystalline and Amorphous 2. What features can be used to distinguish the two types of solid? - Crystalline solids are the most common type of solid. They are characterized by a regular crystalline organization of atoms that confer a long-range order. Amorphous, or non-crystalline, solids lack this long-range order.  ACTIVITY 2 Directions: This is a short activity that can be done in approximately 10 minutes. Answer the following questions: 1. Which of the substances appears to be made of crystals? - Salt Granules 2. Defend your answer with evidence from your observation. What did you use top help you decide which are crystals, and which are not? - In my situation, I dint have magnifying glass I don’t know how to see if it crystal or not.  ACTIVITY 3 Directions: Read and answer each question carefully. 1. Which has greater density, crystalline SiO2 or amorphous SiO2? Why? - Whereas amorphous solids lack a well-defined arrangement and long-range molecular order. So crystalline solids have more efficient packing than amorphous solids in same volume. Therefore, crystalline SiO2 has greater density than amorphous SiO2. 2. Imagine the primitive cubic lattice. Now imagine grabbing the top of it and stretching it straight up. All angles remain 90o. what kind of primitive lattice have you made? - Primitive rectangular prism lattice 3. The densities of the elements K, Ca, Sc, and Ti are 0.86, 1.5, 3.2, and 4.5 g/cm3, respectively. One of these elements crystallizes in a body-centered cubic structure; the other three crystallize in a face-centered cubic structure. Which one crystallizes in the body-centered cubic structure? Justify your answer. -  POST-TEST 1. D 2. D 3. A 4. B 5. B  MODULE 2.1: PHASE CHANGE  PRE-TEST 1. C 6. B 2. B 7. B 3. A 8. D 4. B 9. B 5. B 10. A  ACTIVITY 2.1 Match Me! Choose the answer that beast matches each of the definitions below. 1. A gas or a liquid; a substance that can flow. C.FLUIDS 2. A gaseous substance that exists naturally as a liquid or solid at normal temperature. A.VAPOR 3. A phase change from liquid to gas. E.VAPORIZATION 4. The curve on a phase diagram which represents the transition between the gaseous and liquid states. B.VAPORIZATION(or condensation) CURVE 5. Melting and boiling points when the pressure is 1 atm. D.NORMAL MELTING AND BOILING POINTS  ACTIVITY 2.2 Directions: Write True or False 1. TRUE 2. TRUE 3. TRUE 4. TRUE 5. TRUE  ACTIVITY 2.4 1. You went for a hike on the mountaintop near your vicinity. To help you regain your strength following the exhausting work, you decide to hard-boil an egg and eat it. To your surprise, water seem to boil quicker than usual, but after 10 mins in boiling water, the egg is still not cooked. Why is that? - you don't cook the eggs long enough, too much water will remain in the eggs so they will be runny. The more water that gets cooked out of the eggs, the tighter the protein webs will be. If they get too tight like when eggs are scrambled for too long, the eggs will become tough and rubbery. On the other hand, if you don't cook the eggs long enough, too much water will remain in the eggs so they will be runny. 2. Why do pressure cookers save time in the kitchen? Explain the effect of pressure on boiling point. - Because under pressure, the heat builds faster and maintains temperature better, so cooking time is reduced. ... The increased pressure inside the cooker increases the boiling point of water above 1000C so more cooking is done before the water actually starts to boil. So ultimately food is cooked faster.  POST-TEST 1. A 6. A 2. C 7. B 3. A 8. C 4. D 9. A 5. B 10. C  MODULE 2.2:  PHYSICAL PROPERTIES  LESSON 1  PRE-TEST 1. D 6. B 2. B 7. B 3. D 8. B 4. C 9. C 5. B 10. A  ACTIVITY 2.1.1 Directions: Locate the words associated with concentration units in the grid. The words can be running in horizontal, vertical, and diagonal directions. F A G S O L U T I O N D D E S A M G H E J Y T I K A K O M N H P O S B D C V A S E A S U O Y E H L G I A F J L T V J L I J R H N E K S P P M D S D O T K C J Y A F Q O G Y I O E V A F E Y T I H R D E G G L F Y R K N J F J E R A S F H U A B T D T S Q L A F E C B O T G T N K B N S O L V E N T E E Y N E R Y O M A F R A N C I S M E C E M O L A R I T Y S G O K C N Y A S E R R E G B C G R N R O O S L Y E E A I H F W K S E C E S J E A F A I T H W F F P E  ACTIVITY 2.1.2 1. Hydrogen peroxide, H2O2 is used by some water treatment systems to remove the disagreeable odor of sulfides in drinking water. An aqueous solution of H2O2 prepared in the laboratory was found to have a concentration of 20.0% by mass. What is the mole fraction of H2O2? 2. What is the molality of a solution containing 0.75 moles of sodium hydroxide in 500 mL of water at 25oC? The density of water at 25oC is 1 g/mL. 1. Solution 2. Concentration 3. Molarity 4. Solvent 5. Percent 6. Volume 7. Solute 8. Molality 9. Mass 10. Mole with the ice on the road some heat is released because of the solvation process. This melts the ice yielding once again an ice water equilibrium. But because of the presence of salt this mixture will re-freeze  at lower temperatures than 0C. In both  cases the lowering of the freezing point will depend on the concentration of salt in the mixture 2. Which would increase more the boiling point of water: salt or sugar? Why? - Sugar had a similar effect on boiling point temperature. Sugar did not raise boiling point temp. as much as salt because sugar molecules are 6 times larger than salt molecules and therefore there are many more salt molecules in 1 tsp than sugar molecules. This results in more salt water bonds than sugar water bonds.  MODULE 3: Colligative Properties and Thermodynamics  LESSON 3.1  ACTIVITY 3.1.1 Directions: Locate the words associated with colligative properties in the grid. The words can be running in horizontal, vertical and diagonal directions  ACTIVITY 3.1.2 Directions: Calculate the problems below. Write your solution and box your final answer on the answer sheets provided. Follow the flow of solving like the examples given above. You may use the Kb and Kf of water in the examples. 1. Calculate the freezing and boiling points of a solution prepared by dissolving 15.5 g of Al(NO3)3 in 200.0 g of water. (Molar mass of Al(NO3)3 is 212.996 g/mol) 2. A solution is prepared by dissolving 120 grams of NaCl in 450 grams of water. Find the freezing and boiling points of this solution. (Molar mass of NaCl is 58.44 g/mol) 1. Electrolyte 2. Solute 3. Colligative 4. Freezing 5. Solution 6. Boiling 7. Molality 8. Mass 9. Solvent 10.  ACTIVITY 3.1.3 Directions: Imagine me! Congratulations! You won the lotto and bought a new car. Since it’s very hot in the Philippines you are required to buy an antifreeze to keep the water in your car’s radiator from boiling. You add 1.00 Kg of ethylene glycol (C2H6O2) antifreeze to 4450 g of water in your car’s radiator. What are the boiling and freezing points of the solution?  ACTIVITY 3.1.4 Directions: Look for a book or search the web for additional information regarding the colligative properties of solution. Refer to the guide questions below. 1. State the effect that dissolving a solute has on each of the following physical properties of a solvent. a. Boiling point - boiling point increases. b. Freezing point - freezing point decreases 2. Explain why the colligative properties of a solvent are affected more by the dissolving of an electrolyte compared to an equal amount of a nonelectrolyte. -  Electrolytes are compounds that dissociate when they dissolve. Since more particles are produced, the effect on the colligative properties is greater for electrolyte solutions than for nonelectrolyte solutions which do not dissociate 3. Are the values of Kf and Kb dependent on the identity of the solvent, the solute, or both? Explain. - The value of Kb or Kf depends only on the type of solvent and not solute dissolved in it. Here, Kb and Kf are molal elevation in boiling point constant and molal depression in freezing point constant respectively.They are characteristic of solvent and independent of the solute. -  LESSON 3.2; Laboratory Procedures in Determination of Solution’s Concentration.  ACTIVITY 3.2.1 Directions: Twist me! Rearrange the letters to get the correct word. 1. NCTOENCITORA - CONCENTRATION 2. TYOMILAR - MOLARITY 3. NILUSOTIO - SOLUTION 4. VESLONT - SOLVENT 5. AUQEOSU - AQUEOUS  ACTIVITY 3.2.3 Grace needs to prepare a sulfuric acid solution using sulfuric acid and distilled water. However, there is no distilled water left on the laboratory. Marie suggested to use the running water from the faucet, but Grace declined. Grace insisted that tap water should not be used in preparing solutions. Explain the basis of Grace’s claims. - The water in the tap is not purified. The majority of municipal tap water contains chlorine. Chlorine is a chemical that is used to destroy bacteria in water. Some minerals, such as fluoride, which reduces tooth decay, can be deliberately dissolved in public drinking water.  ACTIVITY 3.2.4 Objective: Prepare a sodium chloride (table salt) solution and sugar solution. Equipment: Cup, table salt, sugar, timer/stopwatch, table spoon Procedure: 1. Measure amount of table salt using table spoon. Record it. 2. Add the table salt in a ½ cup of water. 3. Stir the solution using the table spoon. 4. Record the time it takes for the salt to be totally dissolved. 5. Picture/draw your set-up in preparing the solution. 6. Do step 1 to 5 for sugar solution. Guide Question: In preparing the solutions, which of the two solutes was dissolved faster  LESSON 3.3; First Law of Thermodynamics  ACTIVITY 3.3.1 Words twist: 1. HIRTONSADMEMCY - THERMODYNAMICS 2. NEGEYR - ENERGY 3. TEHA - HEAT 4. KORW - WORK 5. CELCINAHAM - MECHANICAL  ACTIVITY 3.3.2 1. Manuel has a container that contains a sample of nitrogen gas and a tightly fitting movable piston that does not allow any of the gas to escape. During a thermodynamics process, 200 Joules of heat enter the gas, and the gas does 300 Joules of work in the process. What was the change in internal energy of the gas during the process described above? - 1.) The first law of thermodynamics states that the change in internal energy of a system equals the net heat transfer into the system minus the net work done by the system. In equation form, the first law of thermodynamics is ΔU = Q − W. Here ΔU is the change in internal energy U of the system. 2. The work done when a gas is compresses in a cylinder is 462 J. during this process, there is a heat transfer of 128 J from the gas to the surroundings. Calculate the energy change for this process. Solution Correct option is C) DeltaE=q+w = -128+ 462 334joules  ACTIVITY 3.3.3  ACTIVITY 4.1.3 Directions: Explain the phenomena/theory involved why certain actions affect the rate of reaction. 1. Smaller pieces of charcoal can cook the food faster. - This is because smaller pieces of charcoal have a larger total exposed surface area compared to bigger pieces. Hence, smaller pieces of charcoal can burn faster to produce more heat per second and the food is cooked faster. 2. Storing food in refrigerator makes food last longer. - Cold temperatures help food stay fresh longer. The basic idea behind refrigeration is to slow down the activity of bacteria (which all food contains) so that it takes longer for the bacteria to spoil the food. - 3. Small pieces of food are cooked faster. - Several smaller particles have more surface area than one large particle. The more surface area that is available for particles to collide, the faster the reaction will occur. 4. Cooking of food using pressure cooker can be done faster. - At that pressure, water boils at 121°C (250°F). That means food can cook at a much higher temperature than it ever could at atmospheric pressure—and since cooking reactions speed up at higher temperatures, your food cooks faster. 5. Using platinum in manufacturing nitric acid reduces the production’s cost. - Nitric acid production by the oxidation of ammonia on platinum gauzes .The absorption proceeds at greater rates, and with higher efficiencies,lower gas flow rates and the platinum losses are correspondingly reduced to 180 to 200 mg/ton.  ACTIVITY 4.1.4 Directions: Answer the following questions. You may refer to books and the internet to solidify your explanation. 1. What is the relationship between each of the following factors and the reaction rate: reactant concentration, temperature of the reaction, physical properties of the reactants, physical and chemical properties of the solvent, and the presence of a catalyst? - Increasing the concentration of one or more reactants will often increase the rate of reaction. This occurs because a higher concentration of a reactant will lead to more collisions of that reactant in a specific time period. 2. Why does the reaction rate of virtually all reactions increase with an increase in temperature? If you were to make a glass of sweetened iced tea the old-fashioned way, by adding sugar and ice cubes to a glass of hot tea, which would you add first? - Increasing the temperature increases the average kinetic energy of molecules and ions, causing them to collide more frequently and with greater energy, which increases the reaction rate. 3. Explain why an egg cooks more slowly in boiling water in Denver than in New York City. - Water boils at a lower temperature in Denver than in NYC because the atmospheric pressure is less at high altitudes. At a lower temperature, the cooking process is slower, so the time to prepare a hard-boiled egg is longer.  LESSON 4.2: The Rate Law  ACTIVITY 4.2.1 Match ME! 1. D 2. A 3. C 4. E 5. B  ACTIVITY 4.2.2 Directions: Answer the following problems. The conversion of cyclopropane to propene in the gas phase is a first-order reaction with a rate constant of 6.7 x 1024 s-1 at 500oC.  ACTIVITY 4.2.3 On March 11, 2011, the Fukushima nuclear power plant in Japan was severely damaged by a huge tsunami caused by a strong earthquake. As a consequence, radioactive material has accidentally spilled out of the power plant, exposing its immediate environment to high dose of radiation. Since then, scientists have been monitoring the amount of radiation in the area. Unfortunately, radiation is till high until 2016. Explain why even after almost five years, radiation is till high in the vicinity of the power plant. - Following a major earthquake, a 15-metre tsunami disabled the power supply and cooling of three Fukushima Daiichi reactors, causing a nuclear accident beginning on 11 March 2011. All three cores largely melted in the first three days. The accident was rated level 7 on the International Nuclear and Radiological Event Scale, due to high radioactive releases over days 4 to 6, eventually a total of some 940 PBq (I-131 eq). All four Fukushima Daiichi reactors were written off due to damage in the accident – 2719 MWe net. After two weeks, the three reactors (units 1-3) were stable with water addition and by July they were being cooled with recycled water from the new treatment plant. Official 'cold shutdown condition' was announced in mid-December. Apart from cooling, the basic ongoing task was to prevent