1 CHEM 1180 Sample Exam 5 Name Show your work for each problem to receive credit Guard your test and conduct yourself properly The last sheet of the exam is a periodic table for your use Please be sure to write your name on the back of the exam The value of the gas constant is 0 08206 L atm mol K 1 Below is a picture of an open end manometer with a sample of neon gas The volume of the bulb is 5 61 L The bulb contains 0 0981 mol at a temperature of 55 C Ne a 6 points Calculate the pressure of the neon gas inside the bulb in units of atmospheres b 2 points Convert the answer in part a to units of mmHg c 2 points If the atmospheric pressure is 744 torr calculate the height of the mercury column of the manometer in millimeters 2 2 4 points A 0 984 mol sample of fluorine gas is held in a constant volume container Initially the gas is at 812 torr and 196 C What is the final pressure if the temperature is increased to 25 C 3 A sample of gas at a temperature of 25 C and 760 torr has a density of 2 47 g L a 4 points Write the ideal gas equation b 2 points Write the definition of density in terms of mass m and volume V c 2 points Rewrite the mass in terms of the amount n and the molar mass M Remember n is the number of moles d 4 points Use the information in parts a b and c to derive an equation for the molar mass in terms of the density gas constant temperature and pressure e 4 points Calculate the molar mass of the sample of gas described above if the density is 3 21 g L 3 4 A small sample of oxygen gas is made by heating a 1 21 g sample of potassium perchlorate Potassium perchlorate decomposes according the reaction KClO 3 s KCl s O2 s The gas is collected over water The atmospheric pressure is 760 torr and the laboratory temperature is 25 C The volume of gas collected is 246 mL a 4 points If the vapor pressure of water at 25 C is 23 76 torr calculate the pressure of the oxygen in the tube b 6 points Using the answer in part a calculate the number of moles of oxygen produced c 4 points Calculate the percent yield 4 5 6 points A mixture of gases has the following partial pressures PAr 0 18 atm PKr 0 23 atm PNe 0 42 atm Calculate the total pressure and the mole fractions of each component 6 8 points Given the thermodynamic data given below calculate the heat when 0 221 mole of P4O10 reacts according to the chemical equation P4O10 s 6 H2O l 4 H3PO4 aq Hf P4O10 s 2940 1 kJ mol Hf H2O l 285 83 kJ mol Hf H3PO4 aq 1288 3 kJ mol 7 4 points Phosphorus in its natural state is in the form P4 also known as white phosphorus What is the enthalpy of formation of P4 5 8 10 points How many grams of butane C 4H10 are needed to burn in order to heat 861 g of iron from 22 8 C to 84 0 C Hcombustion C 4H10 l 2635 5 kJ mol c Fe 0 441 J g C 9 10 points Determine the enthalpy of reaction for the hydrogenation of acetylene to form ethane C2H2 g 2 H2 g C2H6 g from the following data 2 C2H2 g 5 O2 g 4 CO2 g 2 H2O l 2 C2H6 g 7 O2 g 4 CO2 g 6 H2O l H2 g O2 g H2O l Hrxn 2 600 x 103 kJ mol Hrxn 3 120 x 103 kJ mol Hrxn 286 kJ mol 6 10 4 points How is the kinetic energy and potential energy within a substance related to that substance s internal energy 11 4 points In the process of blowing up a plastic bag is the bag doing positive or negative work 12 4 points In the process of melting ice is the ice experiencing positive or negative heat 13 6 points State the first law of thermodynamics 7 CHEM 1180 Sample Exam Bonus Name Show your work for each problem to receive credit Guard your test and conduct yourself properly The last sheet of the exam is a periodic table for your use Please be sure to write your name on the back of the exam 1 6 points Predict the order of increasing vapor pressure at a given temperature for the following compounds CH3CH2CH2CH2OH HOCH2CH2CH2CH2OH CH3CH2OCH2CH3 2 6 points Arrange the following substances in order of increasing melting point Si CH3OH CH3CH3 NaCl 3 4 points What type of unit cell is represent below 4 4 points Only two elements are liquids under ordinary conditions bromine and mercury Which would you expect to have the higher surface tension Explain why 8 5 4 points Which substance is more viscous water or glycerol HOCH2CH OH CH2OH Explain why 6 12 points Consider the phase diagram for compound Z The triple point of Z is 25 1 C and 0 50 atm and the critical point is 22 0 C and 21 3 atm A a What is the state of Z at position A b If we decrease the temperature from the compound at position A to 28 2 C while holding the pressure constant what is the state of Z c If we take the compound starting under the conditions of part b and increase the temperature to 15 3 C and decrease the pressure to 0 002 atm what is the state of Z d Would it be possible to make the compound starting under the conditions of part c a solid by increasing just the pressure 9 7 8 points Associate each of the solids BN P4S3 Pb and CaCl2 with one of the following sets of properties a A bluish white lustrous solid melting at 327 C the solid is soft and malleable b A white solid melting at 772 C the solid is an electrical nonconductor but dissolves in water to give a conducting solution c A yellowish green solid melting at 172 C d A very hard colorless substance melting at about 3000 C 8 8 points What types of intermolecular forces are important in each of the following a Solid iodine b Calcium oxide c Carbon dioxide gas d Liquid chloromethane CH3Cl e Liquid hydrogen fluoride