Energetics Questions and Answers

spe determine which one of these would have the largest temperature increase given that they all have the same mass absorb the same amount of energy and start at the same initial temperature Specific Heats Silver 0 235 J g C Iron 0 449 J g C Aluminum 0 903 J g C Copper 0 385 J g C Copper Iron Silver Aluminum Previous Submit

5 Given the reaction NaOH s H O heat of reaction AH is positive negative and the reaction is spontaneous not spontaneous Na aq OH aq 10 6 kJ the the entropy AS is positive negative A reaction is always spontaneous if the enthalpy AH is positive negative and the entropy AS is positive negative

1 point How does the addition of a catalyst affect a reaction Increases temperature of a reaction causing it to progress faster Lowers the activation energy causing a reaction to progress faster D Increases the concentration of the larger reactant allowing the reaction to progress faster Lowers specific heat values allowing a reaction to absorb heat better

points A student places 200 0 g of water at 49 70 C in a calorimeter The student then adds 200 0 g of water at 3 20 C to the calorimeter The temperature after mixing was 28 50 C What is the value of the calorimeter constant

Under which conditions is a reaction spontaneous at all temperatures according to AG AH TAS O AS 0 AH 0 O AS 0 AH 0 O AS 0 AH 0 O AS 0 AH 0

1 point A bottle of water containing 285 grams of water is removed from the refrigerator where the temperature is 6 9 C If it is allowed to warm to the room temperature of 21 9 C how many Joules J of energy were absorbed by the water Specific Heat of water is 4 18 J g C Round your answer to a whole number no decimals do NOT type in any units

The molar enthalpy of fusion AHO for a given substance is 2 8 kJ mol and the molar entropy of fusion AS for this same substance is 35 60 J mol K Calculate AGO at 25 C for the melting of 25 moles of this substance Enter your answer in kJ

4 448 Joules of heat are required to raise the temperature of a 10 gram sample of metal from 10 degrees Celsius to 60 degrees Celsius What is the specific heat of the metal 5 Given the reaction CaCO3 s for this reaction is positive negative CaO s CO g the entropy AS change because it becomes more less random

A sample of Aluminum is heated from 26 2 to 56 6 C If this sample of Aluminum gained 3 027 cal of heat what is the mass of this sample The specific heat of Aluminum is 0 215 cal g C Just type your answer in rounded to one 1 decimal do NOT type in any units

3 points A 3 9 gram sample of food is completely combusted in a calorimeter that contains 503 grams of water at an initial temperature of 22 0 C The final temperature of the water is 36 0 C What is the energy value for this food item in kcal g The specific heat of water is 1 00 cal g C DO Type your answer in to two 2 decimals places do NOT type in any units Type your answer

N O g 2 NO g Which of the following is true about the reaction when the temperature is raised Equilibrium will shift to the left O Equilibrium will shift to the right AH 56 9 kJ No effect on the equilibrium

Metal Calcium 0 647 Iron Silver Specific Heat J g C Gold 0 449 0 235 0 129 In joules how much heat is released when 33 0 g of Ag cools from

Reaction C5H12 g 802 g 5CO2 g 6H O g heat Type Enthalpy Entropy Spont AH AS AG Yes No or Maybe TD

How much energy is found in a single jelly bean if 10 jelly beans are combusted in a bomb calorimeter causing the temperature for 5000 grams of water to rise from 20 C to 45 C The heat capacity of water is 4 J g C Assume no heat is lost to the calorimeter housing 25 kJ O 500 kJ O 50 kJ O 5 kJ

Which statement describes the forms of internal energy associated with chemical or physical changes in the system I Intermolecular forces II covalent bonds III nuclear forces IV kinetic energy OI II and III OI and II O I II and IV OI II III and IV

25 Given the following data calculate AHxn of NO g O g NO2 g Do not look at the thermodynamics tables Show work Write all details and the equations used Show 4 or 5 equations and 4 heats of reactions 10 NO g O3 g NO2 g O2 g AH x 199 kJ O2 g 20 g AH rxn 495 kJ 203 g 302 g AH rxn 427 kJ

Zn s 2HCl aq ZnCl aq H g 153kJ For this reaction at 25 C Change in enthalpy Select Change in entropy I Select J Change in Gibbs free energy This reaction is Select Select because I Select because I Select thus

Under normal room conditions standard pressure at about 20 C water will not boil so we do not observe H O l 40 7 kJ H O g At this temperature the process is Select Select spontaneous non spontaneous because I Select

A method for calculating AG rxn indirectly from thermodynamic table data uses which two thermodynamic quantities AH comb and So O Cm and S m O AHf and Cm AH and S m m

What is Assurr when 40kJ of heat is removed from the system at 200K 0 2 J K O 200 J K 200 J K O 0 2 J K

Use the picture to answer the following question WWW WAME Temperature T1 Volume V1 Volume V2 Temperature T2 What is TRUE about the relationship between temperature and volume temperature and volume are directly related MA temperature and volume are inversely related temperature and volume are exponentially related

Consider these two reactions Reaction 1 20F g O g 2 F g Reaction 2 N g 202 g 2NO g AH 49 4 kJ AH 66 4 kJ Explain which reaction is spontaneous and justify your answer in terms of change in enthalpy and chang entropy

Period Remember It takes 334 Joules to melt one gram of ice at 0 C It takes 334 Joules to change one gram of water at 0 C to one gram of ice It takes 2260 Joules to change one gram of water at 100 C to one from of steam It takes 2260 Joules to change one gram of steam to one gram of water at 100 C Cp Ice 2 06 J g C Cp vapor 2 02 J g C Cp water 4 18 J g C One step problems 1 How many Joules of heat are needed to change 50grams of water at 100 C to steam 2 How many Joules of heat are needed to melt 25 grams of ice 3 How many Joules of heat are needed to change the temperature of 25 grams of water from 25 C to 70 C 4 How many Joules of heat must be removed from 50 grams of water at 0 C to change it to ice 5 How many Joules of heat must be removed from 75 grams of steam at 100 C to change it to hot water at 100 C Two step problems 1 How many Joules of heat are needed to melt 30 grams of ice and then heat the water to 60 C 2 How many Joules of heat are needed to change 40 grams of water at 73 C to steam at 100 C 3 How many Joules of heat must be removed from 68 grams of water at 45 C to change the water to ice 4 How many Joules of heat must be removed from 95 grams of steam at 100 C to cool it to water at 20 C 5 How many Joules are needed to change 38 grams of water at 0 C to steam at 100 C

Thermochemistry You dissolve 0 3 mol of potassium hydroxide in 41 8 mL of H O The temperature of the solution changes from 21 5 C to 45 4 C The specific heat capacity for water is 4 184 J g K density for water d H O 1 00 g mL Calculate the enthalpy change AHxn for the dissolution process Give your answer in kJoules per mole Use correct number of significant figures

3 6 points a The heat of combustion of ethanol CH3CH OH is 23 5 kj ml What is the heat FW ethanol 46 0 g mole density 0 790 g mL of combustion per mole of ethanol P

er these reactions n 1 H g Cl g 2HCl g in 2 20F2 g O2 g 2 F2 g in 3 N g 202 g 2NO3 9 0 te the table for Reaction 3 Assume the process occurs near room temperature Change in Entropy Change in Enthalpy ect Select AH 184 6 kJ AH 49 4 kJ AH 66 4 kJ Select Change in Gibbs Free Energy Select Reactic Select

Acetic acid is responsible for the sour taste of vinegar It can be manufactured using the following re CH OH g CO g CH3C OH g Use tabulated values of bond energies from the table below to estimate AH for this reaction Average Bond Energies Single Bonds Bond Bond Energy kJ mol C C C H C O O H Bond C 0 C 0 AH 347 413 358 467 Multiple Bonds Bond Energy kJ mol kJ 1072 745 K

2 4 points Given the following data AHf CO g 393 5 kJ mole AHf H O 285 8 kJ mole AHf H O g 241 840 kJ mole AHf H g 0 kJ mole AHf O g 0 kJ mole AHf CH g 74 9 kJ mole AHf CH OH g 201 0 kJ mole AHF CH OH 238 4 kJ mole calculate the enthalpy AH for the synthesis of methanol CH OH from methane CH g CH g H O g CH OH H g AH kJ

4 6 points 0 1174 grams of a sample is burned in a calorimeter which has a calorimeter constant of 147 22 j deg The calorimeter also contains 980 0 gram of water The temperature changed from 22 40 C to 24 10 C What is the heat of combustion per gram of the sample Specific heat of water 4 184 j g deg density water 1 00 g mL

Calculate the approximate value for AH using bond energies for the following reaction N g 3 H g 2 NH3 g Use the Table of Bond Energies as needed kJ Type numbers in the boxe 10 points

28 The heat released by the reaction of 100 0 mL 1 00 M HCl with 100 0 mL 0 500 M Ba OH 2 a at 25 C is 5 9 kJ Don t use thermodynamics values table Show wor Calculate 4H Nutr of 2HCl a Ba OH 2 a BaCl2 04 H O 8

the following data to estimate AH for lithium bromic 1 Li s Br2 g LiBr s ce energy cation energy for Li cron affinity of Br energy of Br2 alpy of sublimation for Li kJ mol 807 kJ mol 520 kJ mol 325 kJ mol 193 kJ mol 166 kJ mol

Which of the following statements is not true Entropy is positive for a system that becomes more ordered The change in enthalpy in endothermic reactions has a positive sign O Non spontaneous reactions have a positive free energy O Work done on the system is positive

16 For the following equation below delta H degree equals negative 273K joules If the reaction has already reached equilibrium H2 8 F2 g 2HF g a What will happen to the concentration of each substance when the temperature is raised b What will happen to the concentration of each substance if the temperature is lowered

Rank the following compounds according to the magnitude absolute value of their lattice energy placing the compound with highest magotydniektemisnaithal ensviteremeenitorlekstatt Submit CaO

What amount of heat in kJ is required to convert 10 1 g of an unknown solid MM 67 44 g mol at 15 4 C to a liquid at 42 7 C specific heat capacity of solid 1 95 J g C specific heat capacity of liquid 1 18 J g C AHfus 5 72 kJ mol normal freezing point Tf 28 3 C

Calculate the maximum work that could be obtained from the combustion of 140 g of ethanol C2H5 Use data in the table below Substance Ag s AgCl s Al s Al O3 s C s graphite CO g CO g CHI g CH CI g CH OH Standard Free Energies of Formation of Typical Substances at 298 15 K AGI kJ mol C H g C H g C H g 50 79 58 6 166 2 CO NH 5 197 2 CO NH2 2 aq 203 8 209 1 AG kJ mol 0 109 7 CaCO3 s CaCl s 0 00 68 12 32 9 C H OH 174 8 CH18 1 17 3 Ca s 0 Hint 1576 4 0 137 3 394 4 1128 8 750 2 Maximum work i Substance CaO Ca OH 2 s CaSO4 s CaSO4 H O s 1435 2 CaSO4 2H O s 1795 7 Ch g 0 Fe s 0 741 0 0 228 6 237 2 Fe O3 s H g H O g H O HCI g HNO 1 H SO 1 HC H O 0 Hg 1 Hg g K s KCI s 604 2 896 76 1320 3 95 27 79 91 689 9 392 5 0 31 8 0 408 3 kJ Substance K SO4 s N g NH3 g NH CI s NO g NO g N O g N O g Na s Na CO3 s NaHCO3 s NaCl s NaOH s Na SO4 s O g PbO s S s SO g SO3 g AGi kJ mol 1316 4 0 16 7 203 9 86 69 51 84 103 6 98 28 0 1048 851 9 384 0 382 1266 8 0 189 3 0 300 4 370 4

How much energy is released when 10 0 g of water H O at 50 C is cooled completely frozen and then further cooled to 5 C The boiling point of water is 100 C and the freezing point of water is 0 C AHvap 40 67 kJ mol AHfus 6 01 kJ mol Cvapor 1 84 J g C Cliquid 4 18 J g C Csolid 2 03 J g C 5 64 kJ 65 4 kJ 122 kJ 24 8 kJ 5 53 kJ

pond energies to predict AH for the following reaction 2NC13 g 3H2 g N g 6HCl g problem requires values in your textbook s specific appendice rences Tables to answer this question as the values will not m kJ

W Consider the reaction CaCO3 s CaO s CO g Decrease in entropy delta S 0 Increase in entropy delta S 0

1 3 points Consider the reaction NO g 1 2O2 8 NO2 8 Given the following data S NO 209 72J mol K S O 199 82 J mol K So NO 243 51 J mol K Determine AS in J K of the reaction Do not put units in your answer Report your answer with 2 places past the decimal point Type your answer

The universe tends to move towards Choose all that apply Maximum entropy Minimum entropy Minimum enthalpy Maximum enthalpy

Calculate the Gibb s Free Energy for the following reaction in kilojoules and type it in the blank below CH4 8 202 g CO g 2H O e 817 6 kJ AS 160 6 J K T 35 C Round your answer to two decimal places You do not need to type in the units A LI

4 Increase in entropy delta S 0 2 points Consider the process H O 1 H O s O Decrease in entropy delta S 0 Increase in entropy delta S 0

For the system 2NO2 g N2O4 g AG 7 90kJ mol If the system was initialized using enough NO to create a partial pressure of 0 487 atm and enough N O4 to create a partial pressure of 0 315 atm calculate the value of AG T 283 K in kJ mol for these non standard conditions prevailing at the start Report your answer with 2 places past the decimal point Do not add units in your answer

Which of the followings are state functions Select all that apply Incorrect choices will be penalize Enthalpy Temperature 00 Work Internal Energy Heat Gibbs free energy Entropy

13 2 points Consider the reaction 2H O 1 2H g O g O Decrease in entropy delta S 0 Increase in entropy delta S 0

Which of the following statements about heat and work is CORRECT O Heat is a state function O Work done on the system has a negative sign O Work is done when the volume of a system changes Heat released to the surroundings has a positive sign

Which of the following is not usually associated with a bomb calorimeter a water reservoir O a thermometer an optical lens a source of oxygen

Reaction C6H12 g 802 g 5CO2 g 6H O g heat Na s H O 1 NaOH aq H g heat 2NO2 g heat 2NO g O2 g C2H4 g H2 g C H6 g heat 6CO2 g 6H O g light 602 g C6H12O6 S 2KCIO3 s heat 2KCI s 302 g Natal 2H Yol ON C theat Type Enthalpy Entropy AH AS Spont AG Yes No or Maybe TD