Answer:
ΔH = - 464 kJ/mol
Explanation:
Step 1: Data given
Mass of Mg = 0.243 grams
volume of solution = 100 mL
Initial temperature = 23.0 °C
Final temperature = 34.1 °C
Specific heat = 4.18 J/g°C
Step 2: Calculate the heat transfer
Q= m*c*ΔT
⇒ m = the mass of the solution = 100 grams
⇒ c = the specific heat of the solution = 4.18 J/g°C
⇒ ΔT = The change in temperature = T2 - T1 = 34.1 - 23.0 = 11.1 °C
Q = 100 g * 4.18 J/g°C * 11.1°C
Q = 4639.8 J
Step 3: Calculate moles of Mg
Moles Mg = 0.243 grams / 24.3 g/mol
Moles Mg = 0.01 moles
Step 4: Calculate ΔH
ΔH = 4639.8 J / 0.01 moles
ΔH = 463980 J/mol = 464 kJ/mol
(4.6398 kJ) / (0.0099979 mol) = 464 kJ/mol
Since the reaction is exothermic, the ΔH is negative by convention, so:
ΔH = - 464 kJ/mol
