1. The work done by a system is 8 J, when 40 J heat is supplied to it. What is the
change in internal energy of the system during the process?
2. Given the balanced equation below for the highly exothermic reaction of aluminum
with oxygen to form aluminum oxide:
4Al(s) + 3O2(g) 2Al2O3(s) ∆H = - 1,670 kJ
a. What is the value of ∆H when 2 moles of aluminum react?
b. What is the value of ∆H when 10.8 g of aluminum reacts?
c. A certain reaction releases 6,881 kJ of heat. What mass of aluminum oxide was
produced in the reaction?
3. From the given enthalpies of reaction;
4HCl(g) + O2(g) 2H2O(l) + 2Cl2(g) ∆Hrxn = -202.4kJ/mol
1⁄2 H2(g) + 1⁄2 F2(g) HF(l) ∆Hrxn = -600.0 kJ/mol
H2(g) + 1⁄2 O2 (g) H2O(l) ∆Hrxn = -285.8 kJ/mol
Find:
∆Hrxn for 2HCl(g) + F2(g) 2HF(l) + Cl2(g)
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