Answers and Explanations

REVIEW QUESTIONS

1 . C

An  adiabatic   process is  one in  which   no  heat    flow    takes   place.  An  isothermal  process is  one in

which   the temperature remains the same.   An  isobaric    process is  one in  which   the pressure

remains the same.   An  isometric   process is  one in  which   the volume  remains the same.

2 . A

In  calorimetry,    the amount  of  heat    absorbed    in  a   given   process is  calculated  using   the

following   equation:

q   =   mc∆T

Knowing that    the heat    absorbed    is  100 cal,    the mass    is  10  g,  and the temperature change  is

30°C,   the specific    heat    can be  calculated:

3 . C

The reaction    given   is  a   formation   reaction,   since   the reactant    N 2     is  in  its stable  elemental   state

(gaseous    dimer). The enthalpy    of  the change  of  the reaction    is  the enthalpy    of  formation   of  N,

except  that    since   two moles   of  N   are formed, we  need    to  divide  the value   by  two to  get the

value   per mole.

4 . C

To  answer  this    question,   the ice must    be  imagined    as  passing through the following   stages: ice

from    –15°C   to  ice at  0°C;    ice at  0°C to  water   at  0°C;    water   from    0°C to  water   at  100°C;  water   at

100°C   to  steam   at  100°C;  steam   at  100°C   to  steam   at  110°C.  Once    these   steps   have    been