- D The addition of a catalyst to a system at equilibrium has NO effect.
That’s because all a catalyst does is increase the rate at which a
nonequilibrated system reaches equilibrium.
- A It’s important to know the phase of the elements at standard conditions
(25°C at 1 atm).
Gases: hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine, argon,
krypton, xenon, and radon
Liquids:mercury and bromine (choice (A))
Solids: the rest of the elements
- C By definition, accuracy is the measure of how close experimental data
are to true data, while precision is the measure of how similar
experimental data are to one another. Clearly, the student’s data is very
precise; the values of 1.65, 1.68, 1.71 vary by no more than 4 percent.
However, the average value of the experimental data is nearly 50 percent
off the true value, meaning these results are not very accurate—choice
(C).
