Types of Problems Likely to Be On the Exam! Chapter 6

6.1 The Nature of Energy and Types of Energy
6.2 Energy Changes in Chemical Reactions


Cold packs, whose temperatures are lowered when ammonium nitrate dissolves in water, are carried by athletic trainers when transporting ice is not possible. Which of the following is true of this reaction?
(1) ΔH > 0, process is exothermic
(2) ΔH = 0, since cold packs are sealed
(3) ΔH < 0, process is exothermic
(4) ΔH < 0, process is endothermic
(5) ΔH > 0, process is endothermic



6.3 Introduction to Thermodynamics



Calculate q when 28.6 g of water is heated from 22.0°C to 78.3°C.
(1) 9.37 kJ
(2) 1.61 × 103kJ
(3) 0.385 kJ
(4) 1.61 kJ
(5) 6.74 kJ




6.4 Enthalpy of Chemical Reactions


Galena is the ore from which elemental lead is extracted. In the first step of the extraction process, galena is heated in air to form lead(II) oxide.

2PbS(s) + 3O2(g) → 2PbO(s) + 2SO2(g) ΔH = -827.4 kJ

What mass of galena is converted to lead oxide if 975 kJ of heat are liberated?
(1) 282 g
(2) 406 g
(3) 564 g
(4) 478 g
(5) 203 g


6.1:
6.2: 5
6.3: 5
6.4: 3