Chemistry 30
Unit 1: Energy Changes in Chemical Reactions
Assignment 4: Section 3-1

1.	Predict (do not calculate) whether S will be positive or negative, and explain your answer:	

	a)  6 CO2(g) + 6 H2O(l)  C6H12O6(s) + 6 O2(g)

6	b)  PCl3(l) + Cl2(g)  PCl5(s)

(2 marks each)

	c)  H2O(g)  H2(g) + ½ O2(g)

2.  Calculate S using values from the Thermochemical Data handout.

	a)  4 Fe(s) + 3 O2(g)  2 Fe2O3(s)

2

	b)  C2H4(g) + 3 O2(g)  2 CO2(g) + 2 H2O(l)

2

	c)  H2(g) + Br2(l)  2 HBr(g)

2

	d)  Na(s) + ½ Cl2(g)  NaCl(s)

2

	e)  C2H6(g) +  O2(g)  2 CO2(g) + 3 H2O(l)

2