Question

when one mole of CaCl2 dissolves in water, 81.0kj of heat energy is quickly released. A sample of calcium chloride is dissolved in 150 grams of water. The temperature of the water increases by 4.5 degrees Celsius. What mass of calcium chloride was dissolved?
a) 0.387g
b) 3.87g
c) 3.19 kg
d) 3.87 kg

Answer 1

q = mass x specific heat x delta T
q = 150 x 4.184 J/g*C x 4.5 = 2,824.2 J
1 mol CaCl2 = 110.98 g
110.98 g x (2.824 kJ/81.0 kJ) = 3.869 g = 3.87 g = answer b

Answer 2

thank you, that makes sense but how did u get to the last line