Energetics Questions and Answers

What will be the heat in J related to the system when its AE 721 J and it has received 289 J of work from the surroundings

D Question 5 0 5 pts A person reacts 4 94mol of carbon with 29 22mol of hydrogen gas How much energy is released during the reaction Use a negative number if energy is released and a positive number if energy is added 4C s 5H g C4H10 8 AH 125 6 kJ mol

5 60 Consider the following hypothetical reactions CQ A B B C AH 30 kJ AH 60 kJ a Use Hess s law to calculate the enthalpy change for the reaction AC b Construct an enthalpy dia gram for substances A B and C and show how Hess s law applies 5 61 Calculate the enthalpy change for the reaction PO s 2O g P4O10 s given the following enthalpies of reaction P s 3 O 8 P406 s P4 s 5O g P4010 s 5 62 From the enthalpies of reaction 2 H g O g 2 H O g 3 O g 2 03 g calculate the heat of the reaction 062 1300 0 kJ AH 1640 1 kl AH 2940 1 kJ AH 483 6 kJ AH 284 6 kJ 3H O g 867 7 kJ

3 The following sequence of reactions occurs in the commercial production of aqueous nitric acid AH 907 kJ 4NH 9 50 g 4NO g 6H O l 2NO g O g 2NO g AH AH 139 kJ 3NO H O l 2HNO3 aq NO g Use law Hess s to calculate AHxn for the reaction Determine the total energy change for the production of one mole of aqueous nitric acid by this process 12NH g 210 g 8HNO aq 14H O 4NO g 113 kJ

If a reaction is exothermic and is accompanied by a decrease in entropy of the system then the reaction is A spontaneous at low temperatures only B spontaneous at high temperatures only spontaneous at all temperatures C D nonspontaneous at all temperatures

Use these data to determine the enthalpy change for this reaction Standard Enthalpy of Formation AH Na O s 515 kJ mol Na O s 416 kJ mol Na O s Na O s O 8 A 99 kJ B 99 kJ D cannot determine without AH for O g C 198 kJ

What is the Gibbs Free Energy change for the reaction CHg 8 50 8 3CO g 4H O 1 AH KJ mol S J K mol A 2111 kJ C 108 932 kJ C3Hg 8 104 270 0 8 0 205 CO g H O 0 394 286 214 70 B 2111 kJ D 108 932 kJ

92 38 bar was heated to 221 3 C and placed in a coffee cup calorimeter containing 425 0mL of water at 22 55 C What is the specific heat of copper Type your answer

A chemical equation is shown below 2 C2H6 g 7 Oz g 4 CO g 6H2O g Which type of reaction best classifies this chemical equation Osynthesis O combustion decomposition single replacement displacement

When the kinetic energy of a gas increases pressure stays constant decreases increases

energy in kilojoules would be released if 16mol of ethanol molecules were broken apart into individual oxygen hydrogen and

Which of the following would have an effect on the kinetic energy of a gas volume pressure temperature

26 You are hall way through the final Here is a bra What the number 1 movie the year Mr Brown was bol Answer is c Jurassic Park choose this answer 27 Which of the following intermolecular forces is the strongest alon dipole Hydrogen Bonding e London Dispersion d All of these are equal in strength 28 Which of the following is a property of water a High specific heat b Hydrogen Bonding cAmphoteric a 7587J c 434 23 Chapter 3 Energy 29 How much energy in is absorbed if a 165g sample of water is heated from 8 degrees C to 19 degrees C7 Specific heat of water is 4 18 J g C STO b This is not the correct d Go back select c a 2 5 C d These are all properties of water c 1 4 C b 6207 3J d 1815J od nie 30 What is the final temperature T if 1500J of energy are added to 250g of water initially at 10 degrees C Specific heat of water is 4 18 J g C b 11 4 C d 12 5 C d b 31 What is the energy value kcal g of a 0 92g food item if it is able to heat 200g of water fro 10 degrees C to 19 degrees C Specific heat of water is 1 00 cal g C a 3 72 kcal g c 1 96 kcal g 32 Which of the following is true for an exothermic reaction a Decrease temperature absorb energy b Decrease temperature release energy c Increase temperature absorb energy d Increase temperature release energy b 4 14 kcal g d 0 51 kcal g sib M 01x01 0 enon o

At constant pressure the combustion of 15 0 g of C 2H 6 g releases 777 kJ of heat What is A H for the reaction given below 2 C 2H 6 g 70 2 g 4 CO 2 g 6 H 20 129 kJ O 779 kJ O 3120 kJ 1560 kJ

Upload a photo or a screenshot of 4C s 5H g C4H10 g AH 125 6 kJ mol 1 A line graph representing the energy changes in the reaction 2 An LOL graph modeling changes in chemical and thermal energy

Determine AH vap for a compound that has a measured vapor pressure of 24 3 torr at 273 K and 135 torr at 325 K O 41 kJ mol O 34 kJ mol O 79 kJ mol O 13 kJ mol O 24 kJ mol

QUESTION 15 A chemical reaction that absorbs heat from the surroundings is said to be AH at constant pressure A endothermic positive B endothermic negative C exothermic negative D exothermic positive F exothermic neutral and has a

bum the potato chip and feel the heat They decide to measure this heat by putting a can of water above the burning potato chip so they can measure the heat gained by the water 1 Calorie 1 000 calories 4 184 J 1 cal Specific heat of water is 4 184 J g C They collect the following data mass of water in can initial temperature of water final temperature of water 47 9 g 21 6 C 24 1 C How many Cal were stored in the potato chip Round your answer to 2 decimal places

A student mixed two chemicals to allow them to react The temperature before the reaction was 25 C The temperature after the reaction was 18 C Which of the following is true OO The temperature changed b It s an endothermic reaction It s an exothermic reaction Two of the answers are correct C d

Potential Energy A Ba d T Reaction Coordinate A B Kyna Stevens C D C D energy f Answer the questions using the graph above 1 Is the above reaction endothermic or exothermic exothermic 2 What letter represents the potential energy of the reactants 3 What letter represents the potential energy of the products 4 What letter represents the heat of reaction AH 5 What letter represents the activation energy of the forward reaction 6 What letter represents the activation energy of the reverse reaction 7 What letter represents the potential energy of the activated complex 8 Is the reverse reaction endothermic or exothermic 9 If a catalyst were added what letter s would change

QUESTION 22 Calculate the AE for the process where a balloon loses 655 J of heat and shrinks from the atmosphere doing 382 J of work on it The AE is

QUESTION 23 Given the following reactions 2S s 302 g AH 790 kJ S s O2 g SO2 g AH 297 kJ the enthalpy of the reaction in which sulfur dioxide is oxidized to sulfur trioxide 2SO2 g O2 g 2SO3 g kJ is A 196 B 196 C 1087 D 1384 E 543 2SO3 g

Question 16 A chemical reaction that releases heat to the surroundings is said to be AH at constant pressure A endothermic positive B endothermic negative C exothermic negative D exothermic positive F exothermic neutral and has a

ON 18 The temperature of a 11 8 g sample of calcium carbonate CaCO3 s increases from 24 8 C to 38 0 C If the specific heat of calcium carbonate is 0 82 J g K how many joules of heat are absorbed Answer in 2 sig figs A 130 J B 0 92 J C 130 J D 0 92 J E 11 J

8 In a reaction the potential energy of the reactants is 55 0 kJ to start activate the reaction the reactants must contain 110 kJ It is determined that the potential energy of the product is 35 5 kJ Construct a heating curve describing this reaction Label all parts Explain whether this is endothermic or exothermic and why

During an endothermic change the energy of products is of reactants greater than lesser than O equal to lesser or equal to the energ

40 41 42 43 44 45 46 50 2 points As the intermolecular forces increase the vapor pressure of a liquid increases True False Previous

A Design a Proposal for a Hot Pack and a Cold Pack Based on the data in Data Table 2 for calcium chloride and ammonium chloride determine which compound to use and what quantity of each compound will be needed to make a chemical hot pack and cold pack Both packs should be calculated based on using 100 g of water The hot pack should reach 60 C and the cold pack should go down to 3 0 C from a room temperature of 25 C Create a spreadsheet and graph for CaCl and NH CI Plot the mass on the x axis and change in temperature on the y axis for both graphs The slope will be the change in temperature per gram of salt dissolved Hot Pack Compound needed to achieve 60 C Grams needed per 100 g of water Cold Pack Compound needed to achieve 3 0 C Grams needed per 100 g of water DATA FROM TABLE 2 Calcium Chloride 65 kj mol

A piece of unknown substance weighs 24 7 g and requires 1810 J to increase its temperature from 28 2 C to 61 0 C What is the specific heat of the substance

Use the figure below for problems 3 and 4 Substance H O 1 H O S Al s Fe s Hg 1 C s Specific Heat Capacity 0 C g 4 18 2 03 0 89 0 45 0 14 0 71 3 A 28 7 g sample of iron metal is heated from 22 7 C to 91 5 C How much heat is transferred to the metal in this process 4 1 875 kJ of energy is taken away Q from a 116 4 g sample of an unknown substance When this occurs the temperature of the substance drops from 37 9 C to 19 8 C a Determine the specific heat capacity for the metal b Identify the metal

The conversion of H O to H and O is an endothermic reaction In which direction is the equilibrium shifted when the temperature is a increased b decreased a The equilibrium shifts to the select b The equilibrium shifts to the select

1 Find the amount of heat Q needed to raise the temperature of 5 00g of a substance from 20C to 30C it the specific heat of the substance is 2 01J gC

In a chemical reaction if more energy is required to make the chemical bonds than to break them apart the reaction is endothermic so we see a a b d increase in temperature a decrease in temperature huh no change in temperatur

5 A calorimeter contains 150 0 g of water at 25 1 C A block of copper metal is heated to 100 4 C by putting it in a beaker of boiling water The specific heat of copper metal is 0 385 J g C The copper is added to the calorimeter and after time the contents of the cup reach a constant temperature of 30 3 C What is the mass of the block of copper 6 Methane can be burned and the energy used to heat substances up a How much heat is required to heat 1 00 kg of water from 25 0 C to 90 0 C b Use available heats of formation to determine the change in enthalpy when methane is combusted you will need to write a balanced equation for this reaction

Bromine is one of only two elements that is a liquid at room temperature Bromine has a heat of vaporization of 30 91 kJ mol How much heat is needed to vaporize 20 0 g of Br2

1 A is an experimental set up that can be used to measure the heat of a chemical reaction physical change and determine the specific heat capacity of a substance barometer calorimeter thermometer

Consider the following reactions and corresponding enthalpy changes Reaction C s O g CO g SO g S s O g CS 1 30 g CO g 2SO2 g O 1767 1 kJ O 386 5 kJ O 89 7 kJ 089 7 kJ Enthalpy Change AH 393 5 kJ AH 296 8 kJ AH 1076 8 What is the enthalpy change for the production of liquid carbon disulfide from solid sulfur and solid carbon 386 5 kJ kJ

Calculate the following for test tube 1 and for test tube 2 and record the results in the table the number of moles of copper sulfate used Use 159 60 grams mole as the molar mass of copper 11 sulfate the heat absorbed by the water in joules Use Q mCAT where 10 0 milliliters of water has a mass of 10 0 grams Use 4 186 joules gram degree Celsius as water s specific heat capacity the change in internal energy of the copper II sulfate Assume that the energy released by the copper II sulfate is absorbed by the water the reaction enthalpy in joules mole BIUX X 10pt Moles of copper II sulfate Heat absorbed by water J Change in internal energy J Reaction enthalpy J mol Characters used 155 15000 159 60 4 186 V AVA Test tube 1 EEEEEE Test tube 2 VE

The change in enthalpy is surrounding from system O negative positive O zero O neutral when energy is absorbed b

How much energy in kilojoules would be eleased if 30mol of ethanol molecules were proken apart into individual oxygen hydrogen and carbon atoms Report your answer as a positive value H H H CI H F N H Ethanol HH II H C C O HH 436 kJ mol 431 kJ mol 567 kJ mol 391 kJ mol 201 l mol Average Bond Energies kJ mol 413 kJ mol 348 kJ mol 293 kJ mol 358 kJ mol 485 kJ mol C H C C C N H C C CHC 614 kJ mol 839 kJ mol 799 kJ mol 495 kJ mol 1072 kJ mol 615 kl mol

During exothermic reactions The energy stored in chemical bonds decreases The amount of thermal energy decreases O The products have a lower temperature than the reactants O Energy is created The energy stored in chemical bonds increases Question 3

0 5 lain how differences in bond energy result in ction being exothermic Use the law of servation of energy in your answer

3 Use Hess s Law to determine the AH for the reaction shown below based on the information that follows 10 pts 4 NH g 5O g 4 NO g 6H O g N g O g N g 3H g 2 H g O g 2 NO g 2 NH g 2 H O g AH 180 5 kJ AH 91 8 kJ AH 483 6 kJ AH

GBE Thermochem The thermochemical equation for the reaction of carbon disulfide with oxygen is shown below CS 1 O g CO g SO g AH 1073 6 kJ mol rxn a Balance the equation above And sketch an enthalpy diagram for the reaction b Calculate the mass of carbon disulfide that will react to produce 766 kJ of heat c Calculate the amount of heat generated from this reaction when 11 2 g of sulfur dioxide are produced rxn d Use the equation above to calculate the value of AH for the reaction below AH CS 1 3 2 O g rxn

2 40 41 50 2 points In comparing evaporation and boiling of a liquid which of the following is true All of the answers are correct OOOO They both require the same amount of energy They are both exothermic processes They both result in a decrease in entropy Previous

49 2 points A process in which entropy increases and energy is released will be spontaneous sometimes never always Previous

46 2 points Which of the following would affect the volume of a gas The pressure of the gas All three answers are correct The temperature of the gas The size of the container in which the gas is stored Previous

P Exam3 Part II 27 Consider the reaction 2N O5 g 4NO g O g AH 4910 kJ How much heat in Joules would be required to decompose 43 8 g N O5 g 4pts

29 An unknown metal with a specific heat of 0 790 J g C has a mass of 42 9 g is heated The mass of the liquid water is 31 6 g at an initial temperature of 25 1 C When the hot metal is placed into the water they reach a temperature of 55 7 C What is the initial temperature in Celsius C of the metal when it was heated specific heat of water is 4 184 J g C must show all the calculations 6pts

2 points On the heating cooling curve below which letter represents solid being converted into liquid TEMP OO b C a 6 0 g F A B ENERGY D E