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enthalpy of combustion per gram of liquid methanol, and compare this answer to t

ID: 550088 • Letter: E

Question

enthalpy of combustion per gram of liquid methanol, and compare this answer to that for ethanol in Exercise 95. 97. Some automobiles and buses have been equipped to burn propane (CHs). Compare the amounts of energy that can be obtained per gram of C3Hs (g) and per gram of gasoline, assuming that gasoline is pure octane, CsHis(). (See Example 6.11.) Look up the boiling point of propane. What disadvantages are there to using propane instead of gasoline as a fuel? Answer 98. Acetylene (C2H2) and butane (C4H1o) are gaseous fuels with enthalpies of combustion of -49.9 k]/g and -49.5 k]/g, respectively. Compare the energy available from the combustion of a given volume of acetylene to the combustion energy from the same volume of butane at the same temperature and pressure. 99. Assume that 4.19 × 106 kJ of energy is needed to heat a home. If this energy is derived from the combustion of methane (CH4), what volume of methane, measured at STP, must be burned? (dHocombustion for CH4 =-891 kJ/mol) Answer 100. The complete combustion of acetylene, C2H2(9), produces 1300. kJ of energy per mole of acetylene consumed. How many grams of acetylene must be burned to produce enough heat to raise the temperature of 1.00 gal water by 10.0°C if the process is 80.0% efficient? Assume the density of water is 1.00 g/em

Explanation / Answer

97. Heat of combustiomn of propane = -2202KJ/mol

Energy of propane per gram = (2202KJ/mol / 1mol). (1mol/44g) =50.04 KJ/gm

Heat of combustion of Octane = -5430KJ/mol

Energy of octane per gram = (5430 KJ/mol/1mol). (1mol/114gm)= =47.631 KJ/g

Disadvantages of propane:

1.Propane boiling point is -420C. So it only occupies 80% in fuel tanks.

2. Propane is limited availability.

3. It has less density than gasoline so it gives less mailage in driving.

4. It has higher denser than air it causes the explosion and fire.