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Unit 4
C..9 Modeling Matter: Strong Versus Concentrated
In this activity, you will depict concentrated and dilute solutions of two imaginary acids—one strong
(HSt) and the other weak (HWe).
in referring to an acidic solution, as you recall, strong indicates that all (or nearly aH) acid molecules
have reacted with the water to produce hydronium ions and anions. By contrast, concentrated indicates
that there are a very large number of particles—molecules or ions—dissolved in a particular volume of
solution.
Figure 4.60 (page 377 of your text) depicts possible models for strong and weak acids. In this activity,
you will illustrate the ideas you learned about in Section C.8. Each of the following rectangular boxes
represents 1.0 L of solution. Use H to represent a hydronium ion. Each F4 symbol will represent 0.1 mol
of dissolved hydrogen ions. Do not draw the solution’s water molecules.
Inside each box, draw between 2 and 20 acid molecules, or the appropriate numbers of hydrogen ions
and anions, to illustrate the following conditions:
>
>
>
In
In
In
In
the
the
the
the
first box, depict a concentrated strong acid (HSt) solution.
second box, depict a dilute strong acid (HSt) solution.
third box, depict a concentrated weak acid (HWe) solution.
fourth box, depict a dilute weak acid (HWe) solution.
1
2
3
4
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Student 11) Number:
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Period:
Date:
Use your depictions to answer the following questions:
1.
2.
Explain the difference beeen each pair of words used to describe a solution of an acid or base:
a.
weak, dilute
b.
strong, concentrated
Calculate the molar concenfration (molarity) of hydrogen ions (H) depicted in each of your four
drawings. Recall that each ion you drew represented 0.1 mol of particles.
Box 1
Box 2
Box
3
Box
4
3.
How would the
3.
a.
values for the four solutions that you depicted compare to one another?
Why is it easier to use a single particle to represent 0.1 mol of particles, rather than eying to draw
every particle in 0.1 mol of ions?
b.
5.
pH
How
How
many total particles are actually in
0.1
mol of particles? (Refer to page
161
in Unit
2.)
might your model drawings mislead a viewer about what is actually present in each solution?
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