0.500 g of Ca is added to 50.0 mL of 1.0 M MCI. Once reaction is complete, the t
ID: 503137 • Letter: 0
Question
0.500 g of Ca is added to 50.0 mL of 1.0 M MCI. Once reaction is complete, the temperature of the solution has risen from 25.2 degree C to 71.4 degree C. The reaction proceeds by the following equation: Ca(s) + 2 H^+(aq) rightarrow Ca^2+(aq) + H_2(g) a. Calculate the heat gained by the solution a = m*s* Delta T, where s = 4.184 J/g* degree C m = mass in grams s = specific heat in J/g* degree C Delta T = final temp. - initial temp. b. Heat lost by the reaction: q_rX_n = -q_soln q_rxn = kJ c. Calculate the heat of reaction: Delta H degree = ______ kJ/mol Ca Using Hess' Law, calculate the enthalpy of formation for C_8H_ 8(g) using the following thermodynamic data.Explanation / Answer
a) Heat gained by the solution qsoln = msdT c = heat capacity of water
= (0.5 g ) x (4.184 J/g°C) x (71.4 - 25.2)°C
= 96.65 J
qsoln = 96.65 J
qsoln = 0.0966 kJ
b) Heat lost by the reaction qrxn = - qsoln
qrxn = -0.0966 kJ
c) Heat of the reaction Ho = qrxn / moles of Ca
= -0.0966 kJ / mass of Ca/ molar mass of Ca
= -0.0966 kJ / 0.5 g/ 40 g/mol
= -7.728 kJ/mol
Therefore,
Heat of the reaction Ho = -7.728 kJ/mol Ca
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