homework problem

Question

a noon on a clear day in midsummer, a cylindrical titanium plate is placed in the sun. The plate is painted flat black sio that it will absorb most of the energy from the sunlight raather than reflecting it. The plate is 5 centimeters in diameter, one centimeter thick, has a specific gravity of 4.5, a molecular weight of 47.9 grams per mole and has a specific heat capacity of 25 joules per mole kevin. If the temperature of the plate increased by 17 degrees Fahrenheit, how much energy in units of calories did it absorb from the sun, assuming no heat is reradiated to the surroundings?

Answer 1

Volume of plate = πr²h = π(2.5cm)²(1cm) = 19.635cm³

4.5 g/cm³ x 19.635cm³ x 1 mol/47.9g = 1.844 mol

(17°F - 32) x 5/9 = -8.33°C = 264.66 K

25 J/mol•K x 1.844 mol x 264.66 K x 0.2389 cal/J = 2914.777 cal

 

3000 cal