Energetics Questions and Answers

What is the melting point of the substance modeled by this heating curve Temp C 150 135 120 105 90 75 B 60 45 30 A 15 44 Created by E Lee for Virtual Virginia 2021 C D Heat kJ E F

Rea Reaction 2 20F g O g 2 F2 9 Reaction 3 N g 202 9 2NO g Reaction 2 can be described as an exothermic Question 43 Consider these reactions Reaction 1 H g Chla 2HCK AH 49 4 kJ AH 66 4 kJ AH 184 64 Select Select single replacement decomposition double replacement acid base synthesis reaction

hen 72 4 kJ of heat is applied to a 952 g block of metal the temperature of the metal increases by 30 7 C What is the specific heat of the metal 0 752 J g C

A reaction occurs in a calorimeter resulting in the starting and final temperatures shown below What can you say about the reaction and the enthalpy change AH during the reaction 38 8 C Starting temperature 21 0 C The reaction is exothermic and AH is negative The reaction is endothermic and AH is positive The reaction is endothermic and AH is negative The reaction is exothermic and AH is positive

Which of the following statements is most accurate Energy is stored in chemical bonds and released when the bonds are broken Energy is absorbed when chemical bonds are broken and released when new bonds form More energy is required to form a chemical bond than the energy required to break a chemical bond Answers A and C are both true

All spontaneous processes are exothermic True False Previous

19 2 points The combustion reaction of gasoline C8H18 energy is absorbed and entropy decreases energy is released and entropy decreases energy is released and entropy increases energy is absorbed and entropy increases

Suppose during volleyball practice you lost 2 0 lbs of water due to sweating If all of this water evaporated how much energy did the water absorb from your body Note 2 2 lbs 1 0 kg 2 1 x 10 3

What is the definition of the Law of Conservation of Heat Energy cannot be Blank 1 Blank 2 or

9 A piece of aluminum requires 4 000 J of energy to change from 68 C to 110 C How much aluminum is there

23 A new substance is discovered It is determined that it has a Cp of 3560 J kg C A Is it likely to be an insulator or conductor B Will it change temperature easily

What does ThermoDynamics deal with in Chemistry O a Ob Oc Od e Of Oh h 01 Energy Chemicals Heat Cold A and B Band C A and C A and D All the Above None of the Above

Q or ABCDE Endothermic Ice melting to water Heat in For your hand when you touch something co If AT is positive

7 How much energy is need to raise 50 kg of water from 45 C to 80 C

4 The specific heat of aluminum is 0 214 cal g K Calculate the heat necessary to raise th temperature of 40 0 g of aluminum from 20 0 to 32 3 C

6 PROBLEM SET HEAT CALCULATIONS PRACTICE SC5 ab and SC2 g I am learning to determine the energy change in a chervical reaction Can I calculate the enthalpy change of a chemical reaction 0 using Hess s Law using changes in total bond energy Can I develop a model reaction diagram to illustrate the release or absorption of energy from a chemical reaction system depending upon the changes in total bond energy Using both Hess s Low with Enthalpy of Formation AH values and Bond Enthalpies find the AH for 2 NO g O g 2 NO g Hess s Law with Enthalpy of Formation AH Values Chemical Equation including Energy 14 Temp Phase Chem Kinatie E Potential E attractions Bond Enthalpy Then write the chemical equation with the energy term included Next represent the energy storage and transfer using bar graphs sketch the chemical energy curve ENERGY FLOW 2 NO g O g 2 NO g Reactants Temp Phase Chon bet Potent tattractions ENERGY FLOW is the reaction exothermic or endothermic Products Tanp Phase Chan KE Petal seftracted 2 0 0 2 N Substance NO g POTENTIAL ENERGY NO g AR Bond N O 0 0 NUO 90 TIME 0 34 Reaction Coordinate Bond Enthalpy 607 495 2017 Which is more accurate the Hess Enthalpy of Formation method or the Bond Energy method Why

Determine the moles of air contained in a 101 L cylinder at a pressure of 1 98 atm and a temperature of 340 K

Lana is using a calorimeter to determine the specific heat of a metallic sample She measures out 122 5 grams of her metal and heats it to 86 6 degrees Celsius Then she puts the sample into a calorimeter containing 13 34 grams of water at 49 5 degrees Celsius She measures the temperature of the water in the calorimeter until the number stops changing then records the final temperature to be 65 9 degrees Celsius What is the specific heat of the metal Please answer to three digits after the decimal point and include units Your Answer

ATIONS PRACTICE SC5 ab and SC2 g 3 To find the energy in a pork rind you burn it and calculate the heat transfer with a soda can calorimeter The calorimeter has 275 grams of water c 4 18 The initial temperature was 20 2 C and the final temperature was 39 8 C The pork rind lost 0 97 grams of mass when burned How much energy per gram is in the pork rind stir rod thermometer soda can colorimeter with water food sample paper clip RIABLES work rind ring ring stand Fill in the LOL Chart and label where the process is happening on the heating curve Make the calorimeter water the system CALCULATIONS Temperature Heat Added 9gained glost INITIAL dod ENERGY FLOW O FINAL ANSWER

A Volume increases B Volume decreases Question 8 Solve the following thermochemical reactions 2 HCl Pb PbCl2 H AH 1861 J mole What is the enthalpy if there was 3 86g of PbCl A 25 8J B 10 73 x 101 J C 0 577 D 1 153J Question 9 I 1 Point 1 Point

Rachel burns a 53 gram cracker under a soda can filled with 57 6 grams of water She took the temperature of the water before she began it was 6 0 degrees Celsius After the cracker was done burning the temperature of the water was 84 4 degrees Celsius How many calories of heat were released by the cracker Round your answer to one digit after the decimal point Your Answer

Consider the following information The enthalpy of formation of SrO is AH 592 0 kJ mol The enthalpy of sublimation of Sr is AHsub 164 4 kJ mol The first and second ionization energies of Sr are IE 549 kJ mol and IE 1064 kJ mol The first electron affinity of O is AHEAL 142 kJ mol The bond energy of O is BE 498 kJ mol The lattice energy of SrO is AH lattice 3217 kJ mol Determine the second electron affinity of AH 491 5 kJ mol

3 A 0 501 mol sample of liquid propanol 60 093 g mol is heated from 24 2 C to 3241 C The boiling point of propano is 206 6 C The specific heat of liquid propanol is 2 405 lg C The specific heat of propanol vapor is loyang Flg C The enthalpy of ve vaporization for propanol is 47 5 KJ molo What is the of this process in KJ evergry change

the starting and final temperatures shown below What can you say about the reaction and the enthalpy change AH during the reaction 38 8 C Starting temperature 21 0 C The reaction is exothermic and AH is negative The reaction is endothermic and AH is positive The reaction is endothermic and AH is negative The reaction is exothermic and AH is positive

Reaction Rates Test Summative Assessment In a chemical reaction that takes place at a fixed pressure and volume in a calorimeter the enthalpy change AH is 585 kJ mol Will this reaction result in an increase or a decrease in the calorimeter s water temperature O There will be a decrease in temperature O There will be no change in temperature O There is not enough information to know if the temperature will increase or decrease O There will be an increase in temperature

A 10 0 gram sample of ice at 0 C is warmed up to 40 0 C How much energy is absorbed O 15040J 7520J 3760 J

What is the temperature change when 125 g of water at 70 C loses 1 54 104 J 40 C O 30 C 27 5 C 41 C 4

70 0 g of water are cooled by removing 900 J of heat The final temperature is 4 C What was the initial temperature O 5 C 7 C 3 C 6 C

The following reactant molecules are rearranged to form the product molecules shown The relevant bond enthalpies are given in kJ mol What is the estimated enthalpy change for this reaction Reactants H H H C H 413 H H O H 463 632 kJ mol 198 kJ mol 265 kJ mol H 678 kJ mol Products OEC H H 436 HEH HAH HKH CEO 1072

A sample of iron metal absorbs 4 56 J of heat upon which the temperature of the sample increased from 29 C to 36 C Which of the following is the mass of the sample Cs of iron is 0 46 J g C O 1 22 g 1 42 g O4 12 g O 3 22 g

In a hurricane every second 150 g of water vapor condenses into wate How much heat is tranferred for this conversion in one day O 2 1 x 109 calories 5 1 x10 calories O 1 1 x10 calories O 7 1 x10 calories

What is the value of AH if no heat is lost or gained O 100 O 50 Oo

The value of AH for the reaction below is 72 kJ This reaction is H g Br g 2 HBr g endothermic specific Oneither exothermic nor endothermic exothermic

The reaction of sodium with water results in an increase in temperature of the solution 2Na s 2 H O 1 2Na aq H g 2OH aq Which statement about this reaction is true AHxn 0 reaction is an exothermic redox reaction O AHxn 0 reaction is an exothermic precipitation reaction AHxn 0 reaction is an exothermic redox reaction O AHxn0 reaction is an endothermic acid base reaction O AH 0 the reaction is a neutral redox reaction

The combustion reaction of methane is CH4 202 CO2 2H O AH 802 kJ mol How much heat q is produced when 44 8 L of methane is burned at STP 2250 kJ 802 kJ O 802 kJ 401 kJ O 1604 kJ

Fill in the Blank Give your answer in the available space When AHrxn 0 the reaction is

oph c flipofandl 13 2 403 0 709 mel sample of liquid propenal 60 09 g mnd is heated from 25 3 C to 321 5 C boiling point for propanol is 206 6 C The specific heat of e specific heat of propand vapor is opanel is 47 5 kj mal What is the 1 42 Jc The enthaly of vaporization for evergy charge the prouss in kj I

Thermochemistry You dissolve 1 7 mol of potassium hydroxide KOH in 68 5 mL of H O The temperature of the solution changes from 15 3 C 55 0 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 AHrn for the dissolution process Give your answer in kJoules per mole Use correct number of significant figures

The ancient Romans used calcium hydroxide which reacts with carbon dioxide to form calcium carbonate as mortar in stone structures And if you ever go to Italy you will see that many still stand after 2000 years The reaction for this process is Ca OH 2 s CO g CaCO3 s H O g AH 69 1 kJ mol What is the enthalpy change for a reaction when 3 00 mol of calcium carbonate is formed O 207 3 kJ 69 1 kJ O 72 1 kJ O 207 3 kJ O 69 1 kJ

A chemical reaction has an enthalpy change AHOrxn 73 54 kJ mol Which statement is correct O The reaction is exothermic O The reaction is endothermic The products are higher in energy than the reactants

ated by E Lee for Virtual Virginia 2021 3 At 50 C the substance is a Temp C Select 150 135 120 105 90 75 60 45 30 A 15 sing this heating curve complete the following statements The substance s melting or freezing point can be found between points Select the points alphabetically for example X and Y not Y and X 2 Between points Select and Select Select the points alphabetically for example X and Y not Y and X B Select Select C D E B C D Heat kJ and Select in the liquid phase E F

Order the substances A B C D and E by their specific heat capacities from highest 5 to lowest 1 Assume the masses of each sample are the same Change in Temperature vs Heat Added Temp C 5 highest 3 A Created by E Lee Virtual Vignie 2021 E Heat Energy Added kJ D Choose Choose C B

Extra Credit essment Don t Panic Please show all work for credit Describe how thermodynamics and kinetics are different and how they are connected Be as specific as possible Include some equations Imagine a universe where you could change a law of thermodynamics What would you change Describe it in an equation if possible How would the universe be different based off your change

Reaction CsH12 g 802 g 5CO g 6H O g heat Na s H O 1 NaOH aq H g heat 2NO g heat 2NO g O g 1 C H4 g H g CzHe g heat 6CO g 6H O g light 602 g C6H12O S 2KCIO3 s heat 2KCI s 30 g N g 3H g 2NH3 g heat H g ZnCl aq heat 2HCl aq Zn s Type Enthalpy Entropy Spont AS AG AH Yes No or Maybe TD

m Timing 22 points To a calorimeter containing 300 0 g of water at 20 00 C 10 65 g of NaOH also at 20 00 C was added The temperature of the solution increased to 28 50 C If the specific heat of the mixture is 4 184 Jg C and the small heat capacity of the calorimeter is ignored what is the heat evolved per mole of sodium hydroxide 41 5 kJ 37 4 kJ 45 5 kJ 153 kJ 30 5 Submit

2 1 point Leaves fall from a tree in the Fall energy is released and entropy decreases energy is absorbed and entropy decreases energy is absorbed and entropy increases energy is released and entropy increases Previous

8 1 point Water which has been supercooled to minus 20 C suddenly solidifies into ice energy is absorbed and entropy increases energy is released and entropy decreases energy is released and entropy increases energy is absorbed and entropy decreases

Procedure 1 Record the initial temperature of the water bottles on your data table 2 Fill one bottle with Carbon Dioxide gas and secure it with a stopper leave the other container as is and place a stopper on it as well 3 Place both bottle underneath a heat lamp for 60 minutes then record the temperature of the air inside both bottle with a thermometer and quickly put the thermometer inside without letting the air escape Standard Bottle Bottle with Added CO 2 Initial Temp C 20 5 20 2 Final Temp C 35 2 44 0 Change in Temp C

18 3 points Consider the following process C s diamond C s graphite AHOF Cs diamond 1 9 kJ mol AS Cs diamond 2 38 J molk AHOF Cs graphite 0 kJ mol As Cs graphite 5 74 J molk Determine AG for this process at 280 K in kJ Do not report units in your answer Report your answer with two places past the decimal point Type your answer

Consider the following process C s diamond C s graphite AH Cs diamond 1 9 kJ mol As Cs diamond 2 38 J molk AH Cs graphite 0 kJ mol As Cs graphite 5 74 J molk Determine AG for this process at 271 K in kJ Do not report units in your answer Report your answer with two places past the decimal point Type your answer 40