The heat of a reaction may be found with the equation q=MCAT. A 951 g sample of carbon steel with a specific heat capacity of 0.49 J/(g*K) is heated to 673K and quenched in oil The steel cools
to 523K. Assuming there is no heat lost to the surroundings, calculate the heat absorbed by the oil.
A)
-69.9 kJ
B)
-31.5 kJ
69.9 kJ
D)
71.2 kJ

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

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