hydrogen ion concentration in solution and the pOH is equal to the negative log of the
hydroxide ion concentration in solution. From this we can determine that the range of
possible hydrogen ion concentrations in an acid solution will be about 10–1 to 10 –6.999. The
corresponding range of concentrations of hydroxide ions in the same solutions will be 10–13 to
10 –7.0001. Now calculate the range of the ratio of hydroxide ions to hydrogen ions. For the most
acidic solution, the ratio will be 10 –13/10–1, which is equal to 10–12, or approximately 0. For a
slightly acidic solution, one very close to neutrality, the ratio will be 10–7.001/10–6.999, which is
nearly equal to one. Thus, the range of the hydroxide ions to the hydrogen ions in an acidic
solution is 0 to 1.34 . C
20% (10.013 amu) + 80% (11.0093) = 10.811 amu
35 . C
With respect to the concentration of B, every time the concentration doubles, the rate is four
times faster. [2]x = 4, x = 2.
36 . B
The first thing you should do to verify a Lewis structure of a molecule is to make sure that all
the valence electrons are accounted for. For choice A, acetylene, there are two carbons, each
having four valence electrons, and 2 hydrogens, each having one valence electron. So, choice A
needs to have 10 valence electrons and indeed it has. For choice B, nitrogen dioxide, there is 1
nitrogen, which has 5 valence electrons and 2 oxygens, each having 6 valence electrons—there
should be a total of 17 electrons accounted for. Counting the electrons in choice B you can see
that it has 18 electrons. Choice C, sulfur trioxide, should have a total of 24 valence electrons, 6
from each element. Counting the valence electrons, you’ll see that it has the required 24.
Choice D, boron trichloride, should have, and does have, 24 electrons.
37 . A
You are asked to determine the total pressure in the flask in terms of the partial pressure of
the oxygen gas. To do this, you need to use Dalton’s law of partial pressure. This law says that
the sum of the partial pressures of all the gases in a given vessel is equal to the total pressure.
Since the partial pressure of oxygen is P and you know that there are three times as many
moles of hydrogen as oxygen in the flask, then the partial pressure of hydrogen must be 3P.
Thus, the total pressure in the flask is P + 3P, or 4P.