CH 106 Lecture Notes - Lecture 10: Mechanical Energy, Exothermic Process, Activation Energy

23 views2 pages

lilacwolf625

20 Oct 2016

School

University of Hartford

Department

Chemistry - A&S

Course

CH 106

Professor

Dr.Tione

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Heat-energy that flows from a hotter to a colder object. Heat is a consequence of motion at molecular level. Temperature is the measure of the average speed of molecules. 1 joule is the amount of energy required to raise a 1 km object 10 cm under the effects of gravity. Calorie-heat, 1 cal is amount required to raise the temperature of 1 g of water by. The amount of energy in the universe is constant. It cannot be created or destroyed but is converted and transferred. Forms of energy: electricity (the movement of electrons), light. Potential energy-relation to position or composition (mass and height/position) Bullet is small and light but comes at high speed, determined by mass and speed) The second law of thermodynamics-energy flows spontaneous from hotter objects toward colder objects (the law of entropy) Entropy-a measure of dispersal of energy, nature likes things to become more randomized.

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) +

The use of the British thermal unit (Btu) is common in much engineering work. A Btu is the amount of heat required to raise the temperature of 1 lb of water by 1 °F. Calculate the number of joules in a Btu.

From this conversion, we see that 1 Btu is 252 cal, which is 252×4.184 J = 1054 J.

coralhyena785

CH 106 Lecture Notes - Lecture 10: Mechanical Energy, Exothermic Process, Activation Energy

Document Summary

Get access

Related Documents

CHM 2045C Lecture Notes - Lecture 18: Heat Capacity, Kinetic Energy, Thermal Energy

CHM 103 Lecture Notes - Lecture 12: State Function, Kinetic Energy, Calorie

CHEM103 Lecture Notes - Lecture 8: Sodium Bicarbonate, Ammonium Nitrate, Joule

Related Questions