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South Pasadena  Honors Chemistry
Name __________________________________
4  Salts and Solutions
Period ___ Date ___/___/___
Station 1 – ACIDS, BASES, AND NEUTRALS
Classify each statement as talking about an [A]cid, [B]ase, or [N]eutral.
__B___ feels slippery
__N___ CH3OH
__A___ tastes sour
__A___ H+ donor
__B___ KOH
__B___ increases [OH-]
__A___ turns cabbage juice red
__A___ increases [H+]
__B___ tastes bitter
__A___ H2SO3
__N___ cabbage juice stays purple
__B___ NaHCO3 (baking soda)
Ammonia, NH3, is a weak base. Cabbage juice would turn _blue_ with NH3.
NH3(aq) would be considered a _weak (strong | weak | non) electrolyte.
In water, NH3 can be described by the equation: NH3(aq) + H2O(l)  NH4+(aq) + OH
Indicate one conjugate acid-base pair: _NH3_ and _NH4+__
(or H2O/OH–)
NH3 fits the Arrhenius definition of a base because it _increases [OH–]________________.
NH3 fits the Bronsted-Lowry definition of a base because it _accepts H+_______________.
Draw the solution to the right using + and – for ions and  for molecules.
Indicate the brightness of the light bulb when testing a solution of NH3(aq).



+ 

 –


South Pasadena  Honors Chemistry
4  Salts and Solutions
Station 2 – SOLUBILITY RULES
Circle the Insoluble Ionic Solids and then list the strong acids and strong bases from memory.
MgF2
AgCl
CuSO4
Fe(OH)3
NH4Cl
CdS
PbSO4
CuF2
Na2SO4
NH4OH
Sr(NO3)2
BaCO3
PbBr2
CaC2O4
Strong Acids
Strong Bases
HCl
LiOH
HBr
NaOH
HI
KOH
HNO3
RbOH
Hg2I2
CsF
Ba(OH)2
Na2CrO4
MgO
HC2H3O2
H2SO4
CsOH
HClO3
Ca(OH)2
HClO4
Sr(OH)2
HIO4
Ba(OH)2
South Pasadena  Honors Chemistry
4  Salts and Solutions
Station 3 – SOLUBILITY
Is this well-stirred mixture best
described as saturated or
unsaturated? Justify your
answer.
Saturated. Undissolved solids
(precipitate) indicates there
maximum dissolved solutes.
Consider a solution of NaCl(aq). Draw four water
molecules surrounding each Na+ and Cl ion below.
+
Na

Cl 


Which of the following solutes dissolve well in the
polar solvent, H2O? (check all that apply)
 soluble ionic solids
 insoluble ionic solids
 strong acids
 strong bases
 weak acids
 weak bases
 nonpolar solutes
A test tube has a layer of polar H2O floating on a layer
of nonpolar CCl4 (carbon tetrachloride).
CH3OH (polar), C6H6 (nonpolar benzene), AgCl, KCl,
and I2 (nonpolar) are added to the tube. Which
solutes will dissolve in the CCl4 layer? _C6H6_ _I2_
Which solute does not go into either layer? _AgCl___
South Pasadena  Honors Chemistry
4  Salts and Solutions
Station 4 – SOLUBILITY CURVES
The solubility of NH4Cl(s) at 70˚C is _60_g/100 g H2O.
How much NH4Cl(s) will dissolve in 40.0 g of H2O?
60 g NH4Cl
x
=
x = 24 g NH4Cl
100 g H2O
40 g H2O
If 40.0 grams of H2O, saturated with NH4Cl, is cooled from 70˚C to
50˚C, how many grams of solute should precipitate? __________
50 g NH4Cl
x
At 50°C,
=
x = 20 g NH4Cl
100 g H2O 40 g H2O
24 g – 20 g = 4 g NH4Cl will precipitate
15.0 g NH4Cl dissolved in 40.0 g of H2O at 50˚C would be described as
a ______________(unsaturated | saturated | supersaturated) solution.
Since 15 g < 20 g, the solution is unsaturated.
South Pasadena  Honors Chemistry
4  Salts and Solutions
Station 5 – pH CALCULATIONS
Fill in this chart:
[H+]
1.0 × 10-4 M
[OH-]
1.0 × 10
pH
pOH
Acidic/Basic
M
4.00
10.00
Acidic
5.0 × 10–12 M
2.0 × 10-3 M
11.30
2.70
Basic
1.0 ×10–5 M
1.0 × 10–9 M
5.0
9.0
Acidic
3.2 × 10–12 M
3.2 × 10–3 M
11.5
2.5
Basic
3.3 × 10-2 M
3.0 × 10–13 M
1.48
12.52
Acidic
1.0 × 10–5 M
1.0 × 10-9 M
5.0
9.0
Acidic
1.6 × 10–2 M
6.3 × 10–13 M
1.8
12.2
Acidic
1.0 × 10–10 M
1.0 × 10–4 M
10.0
4.0
Basic
–10
South Pasadena  Honors Chemistry
4  Salts and Solutions
Station 6 – MOLARITY CALCULATIONS
A 2.00 mole sample of NaOH is dissolved in enough water to make 500. mL of solution. What is the
concentration of the solution?
n = 2.00 mol
V = 0.500 L
M=?
n 2.00 mol
M= =
= 4.00 M
V
0.500 L
60.0 grams of NaOH (MM = 40.00 g·mol-1) is dissolved in enough water to make 0.750 L of solution. What is
the concentration of the solution?
 1 mol 
n = 60 g 
V = 0.750 L
M=?
 = 1.5 mol
40.00 g
n 1.5 mol
M= =
= 2.0 M
V 0.750 L
A 250. mL sample of a 0.125 M solution of NaOH contains ________ grams of NaOH.
n=?
V = 0.250 L
M = 0.125 M
n = M × V = (0.125 M)(0.250 L) = 0.0313 mol
40.00 g
0.0313 mol 
 = 1.25 g
 1 mol 
South Pasadena  Honors Chemistry
4  Salts and Solutions
Station 7 – MORE MOLARITY PROBLEMS
Rank these three solutions from most dilute to most concentrated:
__X___ = __Y___ < __Z___
X: 10. g solute in a 300. mL solution
X and Y have the same concentration!
Y: 20. g solute in a 600. mL solution
Z: 20. g solute in a 300. mL solution
You need to prepare 2.00 L of 3.00 M HCl. What volume of stock (12.1 M HCl) do you need?
Mc = 12.0 M
Vc = ?
Md = 3.00 M
Vd = 2.00 L
McVc = MdVd
MdVd (3.00 M)(2.00 L)
Vc =
=
= 0.500 L
Mc
(12.0 M)
Consider a 0.200 M solution of aluminum sulfate, Al2(SO4)3.
[Al3+] = __0.400 M______
[SO42] = _0.600 M________
South Pasadena  Honors Chemistry
4  Salts and Solutions
Station 8 – WEAK ACID EQUILIBRIA
HF is a weak acid.
Finish the dissociation equation for HF.
HF(aq)  F– + H+ (I shouldn’t have included the H2O --Groves)
The Ka for HF is 7.0 x 10-4. Write the equilibrium expression for HF.
[H+][F–]
Ka =
[HF]
Use the ICE Box below to calculate the H+ concentration in a 1.0 M solution of HF.
HF

H+
+
F–
Initial
1.0
0
0
Change
–x
+x
+x
Equilibrium
1.0 – x
x
x
+
–
2
[H ][F ]
(x)(x)
x
Ka =
=
=
= 7.0 × 10–4
x = [H+] = 0.026 M
[HF]
(1.0 – x) 1.0
What is the % dissociation of a 1.0 M HF solution?
0.026
% dissociation =
×100% = 2.6%
1.0
South Pasadena  Honors Chemistry
4  Salts and Solutions
Station 9 – LOOSE ENDS
Solids dissolve best in __hot______ (hot | cool) water.
Gases dissolve best in __cool_______ (hot | cool) water.
Gases dissolve best when the gas pressure above the solvent is __high_____ (high | low).
O2(g) would dissolve in water best:
(A)
20C and 2 atm pressure
(B)
50˚C and 5 atm pressure
(C)
20˚C and 5 atm pressure
(D)
50˚C and 2 atm pressure
Rate these weak acids from weakest to strongest.
HNO2
Ka = 4.0 × 10−4
HC2H3O2
Ka = 1.8 × 10−5
HOCl
Ka = 3.5 × 10−8
HCN
Ka = 6.2 × 10−10
HCN < HOCl < HC2H3O2 < HNO2