CHEM 142 Final Exam

CHEM 142 Final Exam
A positively charged particle and a negatively charged particle are initially far apart.
What happens to their electrostatic potential energy as they are brought closer
together?
decreases
Does the potential energy of the two particles increase or decrease when the distance is
increased?
increase
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If allowed to move, will protons be repelled or attracted to one another?
Electrostatic repulsion is much greater than gravitational attraction and the protons
move apart
When a system does work on its surroundings, w will be a ________ value
negative
When a system ________, ΔE is always negative
gives off heat and does work
Of the following, which one is a state function?
H
Which of the following cannot leave or enter a closed system: heat, work, or matter?
matter
Which cannot leave or enter an isolated system?
matter, work, and heat
What do we call the part of the universe that is not part of the system?
surroundings
From the viewpoint of the chemical reactants as the system, what do you expect for the
signs of q and w in this process?
both of the signs should be negative
Which of the following is an endothermic process?
ice melting and boiling soup
Would the measured heat change represent ΔHΔH or ΔE?
ΔE
If there is a difference, which quantity is larger for this reaction?
ΔE>ΔH
According to the definition of enthalpy, H =E + (PV), so ΔH =Δ E + Δ(PV). For an ideal
gas at constant temperature and volume, Δ(PV) = V ΔP =RTΔn. For this reaction, Δn is
negative. Thus VΔP or Δ(PV) is negative. Because ΔH = ΔE + Δ (PV), the negative
Δ(PV) term means that ΔE is larger than ΔH.