Group work Group # Name of participants CHOOSE ONLY ONE PROBLEM 1) 50.0 g of 1.0
ID: 807418 • Letter: G
Question
Group work Group # Name of participants CHOOSE ONLY ONE PROBLEM 1) 50.0 g of 1.0M HCI solution is added to 50.0 g of 1 0 M NaOH solution in a calorimeter The neutralization reaction causes the temperature of the solution to rise 5 degree C. What is the triangle H degree of reaction per mole of HCI? (use specific heat of solution = 4.18 J/g degree C). 2) Given the following given reactions at right. determine triangle H degree for the following reaction. 3) The reaction between aluminum and iron(II) oxide is very useful to weld metals. The balanced equation is: Note the enthalpies of formation. Triangle H degree , at right: How much heat is released or absorbed when 13.0 g of aluminum is reacted with excess Fe2O3?Explanation / Answer
1) Assuming density of solutions = 1
Heat of reaction = Cp*m*deltaT = 4.18*100*5 = 2.09 kJ. Therefore, detal Ho = 2090 * (1000/50) *1 = 41.8 kJ/mol
2) N2 + O2 ----> 2NO dH = +23.00 kJ (note the reversal of sign)
2NO + O2 -----> 2NO2 dH = -18.0 kJ (note it is multiplied by 2)
2NO2 ------> N2O4 dH = +5.5 kJ (note reversal of sign and it is divided by 2)
dH for N2 + 2O2 ------> N2O4 is obtained by adding all the dH values.
dH = +10.5 kJ
3) dH for the weld reaction = (dHf(Al2O3) + 2dHf(Fe)) - (2dHf(Al) + dHf(F2O3)
= -1669.8 + 24.8 - (-822.2) = -822.8 kJ/mol
13g of Al = 13/26.98 = 0.482 moles.
Therefore the energy released is (-822.8/2)*0.48 = 198.2 kJ
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