Mass of Propane Environmental Chemistry Questions

1……………. A hot water bath is prepared by combusting propane gas and using the heat generated to increase the temperature of the water. The standard enthalpy of formation of propane gas is –104.7 kJ/mol and the specific heat capacity of water (Cp) is 4.18 J ⁰C–1 g–1. Assume these quantities are independent of temperature.

a) What mass of propane is required to heat 250 kg of water from 15⁰C to 60⁰C assuming all the enthalpy change of reaction is completely transferred as heat? Assume the propane is combusted to CO2(g) and H2O(g).

b) How much work was done on the water?

2……………. 5.00 moles of gas have their temperature increased from –10.0°C to 20.0°C. Calculate the heat that must be transferred into the gas if the gas is …

a) He(g) at a constant pressure of 1.5 atm.

b) Ar(g) at a fixed volume of 8.2 m3.

c) CO2(g) at a constant pressure of 20,000 Pa.

3……………A flexible balloon contains 0.350 mol of hydrogen sulfide gas (H2S). Initially the H2S has a volume of 7.00 L and a temperature of 27.0°C. Sunlight heats the balloon such that H2S(g) expands isobarically until the volume doubles. Assume that the H2S may be treated as an ideal gas.

a) What is the initial pressure of the H2S(g)?

b) How much work was done by the H2S(g)?

c) How much was heat supplied to the H2S(g) during the process?