In an adiabatic calorimetry experiment, a 0.1277 g Mg ribbon was M HCI following

Question

In an adiabatic calorimetry experiment, a 0.1277 g Mg ribbon was M HCI following th 2.98°C w was 846. e procedure outlined in this experiment. A temperature increase of added to 200 mL 0.500 as measured. The heat capacity of the product solution and the calorimeter 0 J-K-1 . Calculate AH for this reaction, as performed, and a molar ah, Compare the latter to the literature value that you calculated in question 2. pts) Calculate the 1° for the dissolution reaction of each of the five salts available in the laboratory ing the thermodynamic data given in Table 2. Organize your results in a table.

Explanation / Answer

1) calorimetric experiment

Mg + 2HCl --> MgCl2 + H2

mass of HCl solution = 200 ml x 1 g/ml = 200 g [density of water = 1 g/ml]

Total mass = 0.1277 g + 200 g = 200.1227 g

dTb = 2.98 oC

Cp of calorimeter = 846 J/K

Cp of water = 4.18 J/g.K

So,

dH = -(200.1227 x 4.18 x 2.98 + 2.98 x 846) = -5014 J

moles of Mg = 0.1227 g/24.305 g/mol = 0.00505 mol

moles HCl = 0.5 M x 0.2 L = 0.1 mol

Since moles of Mg is lower, this is the limiting reactant

dH (kJ/mol) = -5014/0.00505 x 1000 = -992.87 kJ/mol

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2) dHo literature value

dHo = dHo(products) - dHo(reactants)

       = (-801.15 + 0) - (0 + 2 x -167.15)

       = -466.85 kJ/mol

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