PRINCIPLES CHEMSTRY CHEM 120
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This 8 page Study Guide was uploaded by Carmela Kilback on Wednesday September 9, 2015. The Study Guide belongs to CHEM 120 at University of Washington taught by Staff in Fall. Since its upload, it has received 37 views. For similar materials see /class/192608/chem-120-university-of-washington in Chemistry at University of Washington.
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Date Created: 09/09/15
Practice questions for Autumn 2006 Chem 120 Final Exam chapters 8 and 9 only Questions were taken from Autumn 2004 exams and do not represent one complete exam Parts of some questions were deleted because material will not be covered on rst exam for Autumn 2006 N l W 00 1 ON illb LA N LA 4 Which of the molecules below would you predict to be soluble in water Why a CH3OH CH3CH2CH3 C K2304 1505 grams of NaOH are dissolved in water The nal volume of the solution is 380 L What is the massvolume percent of NaOH in solution What is the molarity of the solution What is the concentration in equivalents per liter If 25 L of solution contains 010 M CaClz how many grams of Na3PO4 are needed to exactly precipitate all of the calcium as Ca3PO4z What volume of 120 M HCl solution is needed to make 250 L of 100 M HCl The solubility of leadH sulfate is 13 x 10394 M at 25 C What is the equilibrium constant for the reaction PbSO4s S Pb2aq SO4239aq What can you say about the concentration of leadII sulfate in an unsaturated solution When the volume of the following mixture of gases is increased what will be the effect on the equilibrium 4HClg 02g S 2H20g 2Clzg For the exothermic reaction Hzg Clzg S 2 HClg predict the effect of increasing the temperature on the equilibrium If the equilibrium constant for the reaction below is 5147 the concentration of H1 is 050 M and the concentration of Hz is 0069 M what is the equilibrium concentration of 12 Write the equilibrium expression for the reaction Fe203s 3Hzg S 3H20g 2 Fes Calculate the equilibrium constant for CH3COOHaq S CH3COO39aq Haq given equilibrium concentrations of 20 M for CH3COOH and 00060 M for both CH3COO39 and H Consider the reaction Nzg 3Hzg S 2NH3g at equilibrium If a change occurs that increases the equilibrium concentration of N2 from 0350 M to 0400 M what will be the change in equilibrium concentration for H2 and NH3 Classify the following as electrolytes or nonelectrolytes Are any of the electrolytes strong electrolytes a HF b sodium nitrate c CH30H If a solution of potassium hydroxide is mixed with the following what would you predict about the products of each reaction a AgNOg b ammonium chloride Write the molecular and net ionic equations for any reactions that occur To make the concentration of sugar in a cup of coffee 20 mv how many grams of sugar would have to be added to a cup with a volume after adding the sugar of 255 mL If aqueous solution A that is 0505 EqL is separated by a semipermeable membrane from aqueous solution B that is 00762 EqL describe what will happen If you apply pressure equal to the osmotic pressure what will happen Define isotonic solution What happens to a red blood cell when placed in an isotonic solution Why does increasing concentration of reactants increase a reaction rate Chem 120 practice questions for chapters 8 and 9 Answers 1 Elk59 05 14 15 a Predict CH30H is soluble because the 07H bonds in methanol will form hydrogen bonds with the solvent water molecules b Predict is not soluble because the intermolecular forces in propane are dispersion forces which are much weaker than the hydrogen bonding in water Thus water molecules will have stronger interaction with other water molecules than with propane molecules and will not dissolve the propane c Predict that potassium sulfate is soluble because according to solubility rules Table 87 all sulfate compounds are soluble except those with cations Bay Pb2 Ca2 and Sr2 Ionic compounds that are soluble form dipoleion interactions between water and ions that are relatively strong intermolecular forces 396 n v 099 M 198 EqL 28 g 021 L 17 x 10398 An unsaturated solution of leadII sulfate would have a concentration of leadII sulfate less than 13 x 10394 M When the volume is increased the concentrations of the gases decrease and the equilibrium will shift to produce more molecules of gas The shift is toward the reactants because there are more gaseous molecules as reactants than as products Raising the temperature of an exothermic reaction shifts the equilibrium to consume energy and produce more reactants The equilibrium constant at the new temperature will be smaller than the equilibrium constant at the original temperature 00070 M H2013H213 18 x 10395 According to the coefficients in the balanced equation if N2 increases by 0050 M then H will increase by 015 M and NH3 will decrease by 010 M HF and sodium nitrate are electrolytes CH30H is a nonelectrolyte Sodium nitrate is a strong electrolyte a silver hydroxide will precipitate out of solution i Molecular AgNO3aq KOHaq 39 AgOHs KN03aq ii Net ionic Agaq OH39aq 39 AgOHs b No reaction occurs All salts are soluble 50 g When the two solutions are separated by a semipermeable membrane water will ow from solution B through the membrane into solution A decreasing the concentration of in solution A and increasing the concentration in solution B until the two concentrations are equal If pressure equal to the osmotic pressure is applied the ow of water will stop and the concentrations will not change An isotonic solution is a solution with the same osmotic pressure as the solution inside a red blood cell The red blood cell does not change when placed in an isotonic solution With increased concentration more collisions between reactant molecules occurs which increases the number not fraction of collisions that form products CHEM 120 AUTUMN 2006 EXAM 1 OCTOBER 19 2006 Chapter 1 n n n n n n n n n Describe the scienti c method Learn the units and abbreviations forthe metric SI system Distinguish between measured and exact numbers Determine the number of signi cant figures in a measurement 0 Apply rules for signi cant gures in calculations 0 Write numbers in scienti c notation with correct number of signi cant gures Use pre xes to change base units to larger or smaller units Write conversion factors from the units in an equality ln problem solving convert the initial unit ofa measurement to another unit 0 Conversion from US to metric within metric and within US 0 Equalities between US and metric and within US will be given on exam Round off a calculator answer to report an answer with the correct number of significant gures Calculate temperature values in degrees Celsius and kelvins Understand the derivation oftemperature scales 0 Correlate temperatures on two scales Determine density of materials 0 Use methods from laboratory 1 o Formulas for volume will be given on exam Chapter 2 n n n DUDE Classify substances as pure substances or mixtures o Classify mixture as homogeneous or heterogeneous o Classify pure substances as elements or compounds Given the name of an element write its correct symbol from the symbol write the correct name for elements in Table 22 of your book Use the periodic table to identify the group and the period ofan element 0 Decide whether it is a metal nonmetal or metalloid 0 Know the names ofgroups alkali metals alkaline earth metals halogens noble gases transition metals Explain the modern Atomic Theory and the evidence that supports the theory Describe the structure ofan atom 0 Describe electrical charge and location in an atom for a proton a neutron and an electron 0 Explain the evidence that supports the location of protons in the nucleus Given the atomic number and the mass number ofan atom state the number of protons neutrons and electrons Give the number of protons electrons and neutrons in the isotopes of an element Determine atomic mass from relative abundance of isotopes Describe the energy levels sublevels and orbitals in atoms Use the periodic table to write orbital diagrams and electron con gurations Use the electron con gurations ofelements to explain periodic trends 0 Identify location of element in periodic table by its valence electrons Explain trend in atomic size and compare relative atomic sizes of elements 0 Explain trend in ionization energies and compare relative ionization energies ofelements 0 Chapter 3 n n n n Describe alpha beta and gamma radiation 0 Describe source of each type of radiation 0 Explain shielding necessary for each type of radiation Write nuclear equations showing mass numbers and atomic numbers for radioactive decay 0 Write balanced nuclear equations for alpha beta gamma and positron emitters 0 Write balanced nuclear equations forthe production of radioisotopes Describe the measurement of radiation 0 Measurement of activity of a radioisotope 0 Measurement of biological effect in rad and rem Given the halflife ofa radioisotope calculate the amount of radioisotope remaining after one or more halflives Describe the use of radioisotopes in medicine 0 Know isotopes listed in Table 310 0 Describe the use of radioisotopes in PET scans Describe the processes of nuclear fission and fusion not included on exam 1 Make sure to do the rst one it is fun But make sure to ask them if glass slippers are safe in a laboratory Questions for Week of 11104 Cinderella decided to have etchings added to her rather fateful glass slippers in order to commemorate her golden wedding anniversary She took them to Ye Olde Shoe Shoppe to have this done and the shoemaker explained the process to her He told her that what happened was that hydro uoric acid HFaq reacts with the silicon dioxide in the glass to form gaseous silicon tetra uoride and liquid water Cinderella who had been going to night school to nish her education which was sadly neglected in her youth and has tried to balance the equation given her by the shoemaker select the correct balanced equation a 102 s HF aq gt SiF4 g H20 1 b 23102 s 8HF aq gt ZSiF4 g 4H20 1 c 102 s 4HF aq gt SiF4 g 2H20 1 d 13102 s 4HF aq gt ISiF4 g 2H20 1 Explanation and reasoning why they are correctincorrect and why a student might choose them a incorrect because the numbers of atoms per element in the products are not equal to the numbers of atoms for each element of the reactants There are 4 F atoms in the product to the l in the reactant and there are 2 H atoms in the product compared to the l in the reactant and l O atom in the product compared to the 2 O atoms in the reactant A student might choose this if they saw that this was the correct unbalanced equation failed to read the question correctly andor didnampAcircamp82l7t do their math correctly b incorrect although these numbers to balance out they are not the smallest whole numbers of atoms possible which makes this answer less acceptable than answer c where the atoms balance out with smaller coef cients A student might choose this answer if they have done this by trial and error and not realized that they could reduce their coefficients by diViding all of them by 2 c correct because all the atoms in the reactant and the product balance out with the lowest possible number of coef cients A student OUGHT to choose this answer d incorrect although the atoms per element balance out on the product side and the reactant side of the equation it is unnecessary to use 1 as a coefficient A student might choose this answer if they had not seen choice c or were under the impression that you were supposed to put a coefficient of l in front of each substance that did not have a greater coefficient Which of the following is a characteristic of an oxidationreduction reaction AA solid forms from the mixing of two solutions BAn H ion is transferred due to a reaction between an acid and a base compound CAn electron gets transferred from one element or compound to another AIncorrect this is a characteristic of a precipitation reaction B Incorrect this is a characteristic of an acidbase reaction CThis is the correct answer Whenever there is a metalnonmetal reaction they are classified as oxidationreduction reactions due to the electron transfer Concept Learning the fundamentals of balancing chemical reactions Q When balancing a chemical equation one must always a change the formulas for the reactants and or products to balance the equation b use the smallest whole numbers for coefficients c start with examining the least common molecule d use fractions if dealing with compleX molecules e all ofthe above The correct answer is b because the conventional method always uses the smallest whole number integers Answer a is incorrect because you can t change the chemical formulas without changing the entity of the molecule Answer c is incorrect because bigger molecules have more parts to balance whereas smaller molecules are easier to work with Answer d is incorrect because you always want whole number integers you can t have half of a molecule Answer e is incorrect for the above reasons Which of these compounds is a type three coumpound A is correct because the compound is made from two nonmetals the name is boron tri uoride B is wrong because it is a type 2 compound made from a transition metal and a nonmetal C is wrong because it is made from a metal that only forms one cation and a nonmetal D is wrong because it is a polyatomic ion People could get this answer wrong because they don t have a clear understanding of type 1 type 2 type 3 and polyatomic ions Name the following Type II Binary Compound Hg2Br2 A Dimercury dibromide B Mercury 11 bromide C Mercury 1 bromide D Mercury bromide Correct Answer C The answer is correct because the compound is a Type II Binary Compound and Mercury 1 ions always occur bond together in pairs to form Hg22 A is incorrect because the compound is a Type II Binary Compound meaning it has one metal and one nonmetal You do not use pre xes when naming this type of compound B is incorrect because this answer refers to the mercury cation Hg2 which is not diatomic D is incorrect because you must use roman numerals to identify the charge on the cation when naming Type II Binary Compounds Here are some equations that need to be balanced Ammonia gas reacts with oxygen gas to form nitrogen monoxide and water Pb302s HNO3aq gt PbNO33aq H20l CaHz s H20 1 gt CaOH2 aq H2 g Barium Oxide reacts with solid aluminum to form aluminum oxide and solid barium
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