CHM 112 Chapter Notes - Chapter 7: Endothermic Process, Chemical Equation, Enthalpy

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14 Sep 2016

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Center of mass: money, time, energy bomb calorimter --> a piece of equipment designed to measure change in energy reaction for combustion reactions at constant volumes. Calorie --> shorthand notation for the kilocalorie or 1000 calorie. Also called the nutritional calorie calorie --> the amount of energy needed to raise 1g of water by 1 c = 4. 184 j. Calorimetry --> the experimental procedure used to measure the heat evolved in a chemical reaction. Chemical energy --> potential energy in the attachment of atoms or because of their position coffee-cup calorimter --> a piece of equipment designed to measure enthalpy of reaction for reactions at a constant pressure. Conservation of energy requirement --> the total energy change of the system and surroundings has to equal zero. Electrical energy --> kinetic energy associated with the flow of electrical charge endothermic reaction --> a chemical reaction that absorbs heat from its surroundings - h.

Related Questions

Question 2 Energy Calculations

a) Calculate the heat energy (q) when 12.0 g of water is heated from 20oC to 100oC. The

specific heat for water is given in your textbook.

b) Is the process of heating water exothermic or endothermic? Explain your answer.

Question 3 Energy Calculations

You dissolve 0.1 mol of ammonium nitrate in 100 mL of H2O. The temperature of the solution

changes from 22oC to 15oC. The specific heat capacity for water is 4.184 J/g.K. Show all

calculations on a separate sheet of paper!

a) Is this reaction endothermic or exothermic?

b) Calculate the heat, q, released or absorbed in the dissolution reaction.

c) Calculate the enthalpy change, ?Hrxn (kJ/mol), for dissolving 1 mol of ammonium nitrate.

Question 4. A gas expands from 264 mL to 971 mL at constant temperature. Calculate

the amount of work done in Joules by the gas when it expands against a constant pressure of 955

torr.

Question 5 Energy Calculations

a) The nutritional calorie (Calorie) is equivalent to 1 kcal. One pound (1.0 lb) of body fat is

equivalent to 4.1 x 103 kcal. Express this quantity in joules and kilojoules. Use

scientific notation for your answer!

b) If an athlete expends 1850 kJ/h (kilojoules per hour), how long does he have to exercise

to work off 1.0 lb of body fat?

c) The average amount of calories burned during running is 125 kcal/mile. How many

miles does this athlete have to run to burn off 1.0 lb of body fat?

Question 6

Calculate ?Ho for the following reactions at 298 K. Give the balanced thermochemical

equations and show the correct physical state in each equation. Calculate the enthalpy change

for each reaction. You will find thermochemical data in the back of your textbook in Appendix 3

(p. A-8 to A-12)

a) The formation of 1 mol of HCl (gas) from its elements

b) The formation of 1 mol of sodium chloride from its elements

c) The combustion of 1 mol glucose to water and carbon dioxide

d) HCl(g) + NH3(g) ? NH4Cl(g)

Question 7

Calculate heat of formation of SO2 under nonstandard state conditions, given the following

equations

SO2(g) +

At constant pressure, the combustion of 10.0 g of C2Hg(g) releases 518 kJ of heat. What is AH for the reaction given below? 2 C2H6(g) +- 7 O2(g) rightarrow 4 CO2(g) + 6 H2O(l). -779 kJ -1560 kJ -86.1 kJ -3120 kJ Use the information provided to determine Delta H degree r times n for the following reaction: CH4(g) + 3 Cl2(g) rightarrow CHCI3(I) + 3 HCI(g) Delta H degree r times n = ? -217 kJ -335 kJ +662 kJ +117 kJ -151 kJ Choose the reaction that illustrates Delta H degree f for NaHCO3. Na(s) + 2 H(g) + C(s) + 3 O(g) rightarrow NaHCO3 (s) Na(s) + H2(g) + C(s) + O2(g) rightarrow NaHCO3 (s) Na+(aq) + H2O (I) + CO2 (g) rightarrow NaHCO3 (s) Na(s) + 1/2 H2(g) + C(s) + 3/2 O2(g) rightarrow NaHCO3 (s) Na+(aq) + HCO3 -1 (aq) rightarrow NaHCO3 (s) Use the standard reaction enthalpies given below to determine Delta H degree r times n for the following reaction: 4 SO3(g) rightarrow 4 S(s) + 6 O2(g) Delta H degree r times n = ? Given: SO2(g) rightarrow S(s) + O2(g) Delta H degree r times m = +296.8 kJ 2 SO2(g) + O2(g) rightarow 2 SO3(g) Delta H degree r times n = -197.8 kJ -494.6 kJ -791.4 kJ 1583 kJ -293.0 kJ -692.4 kJ Which of the following statements is TRUE? State functions do not depend on the path taken to arrive at a particular state. Energy is neither created nor destroyed, excluding nuclear reactions. Delta Hr times r can be determined using constant pressure calorimetry. Delta H r times n can be determined using constant volume calorimetry. All of the above are true. How much energy is evolved during the formation of 98.7 g of Fe, according to the reaction below? Fe2O3(s) + 2 Al(s) rightarrow Al2O3(s) + 2 Fe(s) Delta H degree r times n = 852 kJ 01.51 times 103 kJ 241 kJ 0482 kJ 4.20 x 103 kJ 753 kJ Given w = 0, an endothermic reaction has the following. - Delta H and + Delta E Delta H and -Delta E - Delta H and -Delta E + Delta H and +Delta E Which of the following substances (with specific heat capacity provided) would show the greatest temperature change upon absorbing 100.0 J of heat? 10.0 g ethanol, Celharol = 2.42 J/g degree C 10.0 g Ag, CAg = 0.235 J/g degree C 10.0 g Au, CAu = 0.128 J/g degree C 10.0 g Fe, CFe = 0.449 J/g degree C 10.0 g H2O, CHO = 4.18J/g degree C Which of the following processes is endothermic? a hot cup of coffee (system) cools on a countertop the vaporization of rubbing alcohol the chemical reaction in a "hot pack" often used to treat sore muscles the freezing of water the combustion of propane

Show transcribed image text At constant pressure, the combustion of 10.0 g of C2Hg(g) releases 518 kJ of heat. What is AH for the reaction given below? 2 C2H6(g) +- 7 O2(g) rightarrow 4 CO2(g) + 6 H2O(l). -779 kJ -1560 kJ -86.1 kJ -3120 kJ Use the information provided to determine Delta H degree r times n for the following reaction: CH4(g) + 3 Cl2(g) rightarrow CHCI3(I) + 3 HCI(g) Delta H degree r times n = ? -217 kJ -335 kJ +662 kJ +117 kJ -151 kJ Choose the reaction that illustrates Delta H degree f for NaHCO3. Na(s) + 2 H(g) + C(s) + 3 O(g) rightarrow NaHCO3 (s) Na(s) + H2(g) + C(s) + O2(g) rightarrow NaHCO3 (s) Na+(aq) + H2O (I) + CO2 (g) rightarrow NaHCO3 (s) Na(s) + 1/2 H2(g) + C(s) + 3/2 O2(g) rightarrow NaHCO3 (s) Na+(aq) + HCO3 -1 (aq) rightarrow NaHCO3 (s) Use the standard reaction enthalpies given below to determine Delta H degree r times n for the following reaction: 4 SO3(g) rightarrow 4 S(s) + 6 O2(g) Delta H degree r times n = ? Given: SO2(g) rightarrow S(s) + O2(g) Delta H degree r times m = +296.8 kJ 2 SO2(g) + O2(g) rightarow 2 SO3(g) Delta H degree r times n = -197.8 kJ -494.6 kJ -791.4 kJ 1583 kJ -293.0 kJ -692.4 kJ Which of the following statements is TRUE? State functions do not depend on the path taken to arrive at a particular state. Energy is neither created nor destroyed, excluding nuclear reactions. Delta Hr times r can be determined using constant pressure calorimetry. Delta H r times n can be determined using constant volume calorimetry. All of the above are true. How much energy is evolved during the formation of 98.7 g of Fe, according to the reaction below? Fe2O3(s) + 2 Al(s) rightarrow Al2O3(s) + 2 Fe(s) Delta H degree r times n = 852 kJ 01.51 times 103 kJ 241 kJ 0482 kJ 4.20 x 103 kJ 753 kJ Given w = 0, an endothermic reaction has the following. - Delta H and + Delta E Delta H and -Delta E - Delta H and -Delta E + Delta H and +Delta E Which of the following substances (with specific heat capacity provided) would show the greatest temperature change upon absorbing 100.0 J of heat? 10.0 g ethanol, Celharol = 2.42 J/g degree C 10.0 g Ag, CAg = 0.235 J/g degree C 10.0 g Au, CAu = 0.128 J/g degree C 10.0 g Fe, CFe = 0.449 J/g degree C 10.0 g H2O, CHO = 4.18J/g degree C Which of the following processes is endothermic? a hot cup of coffee (system) cools on a countertop the vaporization of rubbing alcohol the chemical reaction in a "hot pack" often used to treat sore muscles the freezing of water the combustion of propane

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CHM 112 Chapter Notes - Chapter 7: Endothermic Process, Chemical Equation, Enthalpy

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