Question
1. Use given values as stated below.
2. Clearly State Answer
3. Message me if You are currently working on the problems.
Classify each of the following elements as an electrical conductor, insulator, or semiconductor. (Use the drop down menus to choose either C, I, or S for each.) Phosphorus Mercury Carbon (graphite) Platinum Germanium For an adventurous climber scaling Mt. Aggie, which of the following are state functions? (Enter the letters corresponding to all that are state functions.) Height of the mountain Gravitational potential of a climber at the peak Energy consumed in climbing to the top of the mountain Distance travelled in climbing to the mountain top Use bond energies from this table to estimate the heat of reaction for the following process: The enthalpy diagram below depicts a chemical reaction involving the generic substances A2, B2, and AB. Which of the statements that follow are true for this reaction? Enter the letters corresponding to ALL of the true statements (A, CE, BDF, etc.). If the reaction were carried out in an insulated container, the system would get hotter. AB is a product. A2 is a product Delta H for the reaction is positive. The reaction is endothermic. The reacting system absorbs heat from the surroundings. How much energy is needed to warm 116 ml_ of water (about 1 cup) from 27.3degree C to 92.3degree C? The density of water is 1 g/ml, and the specific heat of water is 4.184 J g"-1 degree C"-1. A 243.3-g magnesium engine part at an initial temperature of 3.32degree C absorbs 87.30 kJ of heat. What is the final temperature of the part? ( The specific heat of magnesium = 1.016 J g"1 K"1. Enter your answer in degree s C, using "C" for the unit.) Suppose that 29.68 g of ice at -14.0degree C is placed in 42.38 g of water at 92.8degree C in a perfectly insulated vessel. Calculate the final temperature. (The molar heat capacity for ice is 37.5 J K"1 mol"1 and that for liquid water is 75.3 J K"1 mol"1. The molar enthalpy of fusion for ice is 6.01 kJ/mol. You must answer in Kelvin, not degree C.) A 1.79 g sample of caffeine (C8H10N4O2) burns in a constant-volume calorimeter that has a heat capacity of 7.55 kJ/K. The temperature increases from 297.65 K to 303.71 K. Determine the heat (qv) associated with this reaction. Now use the data above to find AE for the combustion of one mole of caffeine.
Explanation / Answer
4) Phosporous - C
Mercury - C
Carbon( graphite) - C
Platinium-C
Germanium- S
5) A,B
6) dH = BE( reactants)-BE( products) = H-H + C-C+ C=C + 6C-H - 8C-H -2C-C
= 432 + 614-347-2(413) = -127 KJ/mol
7) B,D,E,F
8) heat required = specific heat of water x mass of water x temp change
= 4.184 x 116 x (92.3-22.3) = 33974 J = 33.974 KJ
9) 87.3 x1000 = 243.3 x1.016 x ( T-3.32)
T = 356.49 C
10) heat gained by ice = heat lost by water
( 29.68/18) x ( T-(-14)) ( 37.5) + (6.01x1000x29.68/18) = (42.38/18) x ( 75.3)(92.8-T)
61.83T + 865.66 + 9909.8 = -177.29 T+16452.5
T = 23.74 C = 23.74+273 = 296.74 K = 297 K
11) heat = ( 1.79/194.2) x ( 7.55) x( 303.71-297.65) = -0.4217 KJ = 42.17 J
12) dE for 1 mole caffeine = dE for 194.12 gm cafeine
= ( 0.4217) x ( 194.2/1.79) = -45.75 KJ/mol
