4.   Anthracite coal releases about 30 kJ/g when it is burned.  How many pounds of coal      would be required to heat 500 L of water from 20 °C to 100 °C if only 30% of the heat      obtained from burning the coal was available to heat the water?   ( 1 kg = 2.2 lbs.)                  lbs.

A 4.81 g sample of an unknown salt (MM = 116.82 g/mol) is dissolved in 150.00 g water in a coffee cup calorimeter. Before placing the sample in the water, the temperature of the salt and water is 23.72°C. After the salt has completely dissolved, the temperature of the solution is 28.54°C. Given that 154.81 g of solution increased in temperature by 4.82 °C, how much heat, in J, was gained by the solution? Assume the specific heat of the solution is the same as water, 4.184 J/g･°C     ______ J?

In a calorimetric analysis, 2.42 g of potassium chloride is weighed. The heat of solution of this salt is measured and calculated as 601 J. The molar heat of solution of potassium chloride is calculated. The actual value of the molar heat of solution of potassium chloride is 17.2 KJ/mol. Comparing with this actual value, what is the relative error? (Note: the molar mass of potassium chloride is 74.6 g/mol.)

C. Using AH from (a) how many moles of water could be heated from 20.0 C to 35.0⁰ C by the burning of propane? #₂0 = 4.184 kJ/kg.