Acid bronsted

2. Properties of acids and basesProperties of acids and bases
•Get 8 test tubes. Rinse all tubes well with
water. Add acid to four tubes, base to the other
four.
•Touch a drop of base to your finger. Record
the feel in the chart (on the next slide). Wash
your hands with water. Repeat for acid.
•Use a stirring rod, add base to the litmus and
pH papers (for pH paper use a colour key to
find a number). Record results. Repeat for acid.
•Into the four base tubes add: a) two drops of
phenolphthalein, b) 2 drops of bromothymol, c)
a piece of Mg, d) a small scoop of baking soda.
Record results. Repeat for acid.
•Clean up (wash tubes, pH/litmus paper in
trash).

3. BubblesNRBaking soda
BubblesNRMagnesium
*Yellow*BlueBromothymol
*Cloudy/
white
*PinkPhenolphthalein
RedBlueLitmus (blue or red)
114pH (# from the key)
Not slipperySlippery
Feel (choose slippery
or not slippery)
SourBitterTaste
HCl(aq)NaOH(aq)
ObservationsObservations
*Usually, but not always

4. pHpH
•There are many ways to consider acids and
bases. One of these is pH. Read pg. 368-70.
•[H
+
] is critical in many chemical reactions.
•A quick method of denoting [H
+
] is via pH.
•By definition pH = – log [H
+
], [H
+
] = 10
-pH
•The pH scale, similar to the Richter scale,
describes a wide range of values
•An earthquake of “6” is 10´ as violent as a “5”
•Thus, the pH scale condenses possible
values of [H
+
] to a 14 point scale (fig. 2, p370)
•Also, it is easier to say pH = 7 vs. [H
+
] = 1 x 10
–7

5. Calculations with pHCalculations with pH
Ans: 4.2
3.98 x 10
–8
M
Try questions 2 and 6 (a-b) on page 375
Q: What is the pH if [H
+
]= 6.3 x 10
–5
?
pH = – log [H
+
]
(‘6.3’, ‘exp’ or ‘EE’, ‘5’, ‘+/-’, ‘log’, ‘+/-’)
(‘-’, ‘log’, ‘6.3’, ‘exp’ or ‘EE’, ‘-’, ‘5’)
Q: What is the [H
+
] if pH = 7.4?
[H
+
] = 10
–pH
mol/L
(’10’, ‘x
y
’, ‘7.4’, ‘+/-’, ‘=‘)
(’10’, ‘^’, ‘-’, ‘7.4’, ‘=‘)

6. Pg. 375Pg. 375
2 a)pH = – log [H
+
] = – log [1x10
–8
] = 8.0
b)pH = – log [H
+
] = – log [1x10
–7
] = 7.0
c)pH = – log [H
+
] = – log [2.5x10
–6
] = 5.60
d)pH = – log [H
+
] = – log [1.3x10
–4
] = 3.89
6 a)[H
+
] = 10
–pH
= 10
–5.4
= 4 x 10
–6
mol/L
b)[H
+
] = 10
–pH
= 10
–5.72
= 1.9 x 10
–6
mol/L

7. Historical views on acidsHistorical views on acids
•The more recent Bronsted-Lowry concept is
that acids are H
+
(proton) donors and bases
are proton acceptors
Ionization
+ClH
H
H
O
+
H
H
HO Cl+
•O (e.g. H
2
SO
4
) was originally thought to cause
acidic properties. Later, H was implicated,
but it was still not clear why CH
4
was neutral.
•Arrhenius made the revolutionary suggestion
that some solutions contain ions & that acids
produce H
3
O
+
(hydronium) ions in solution.

8. The Bronsted-Lowry conceptThe Bronsted-Lowry concept
•In this idea, the ionization of an acid by water
is just one example of an acid-base reaction.
•Acids and bases are identified based on
whether they donate or accept H
+
.
•“Conjugate” acids and bases are found on the
products side of the equation. A conjugate
base is the same as the starting acid minus
H
+
.
+ClH
H
H
O
+
H
H
HO Cl+
acid baseconjugate acidconjugate base
conjugate acid-base pairs

9. Practice problemsPractice problems
Identify the acid, base, conjugate acid,
conjugate base, and conjugate acid-base pairs:
•Reference: pg. 386 – 387
•Try Q18 (p389), Q 8 & 11 (p392): do as
above
acid base conjugate acidconjugate base
HC
2
H
3
O
2
(aq) + H
2
O(l) ® C
2
H
3
O
2
–
(aq) + H
3
O
+
(aq)
conjugate acid-base pairs
acidbase conjugate acidconjugate base
OH
–
(aq) + HCO
3
–
(aq) ® CO
3
2–
(aq) + H
2
O(l)
conjugate acid-base pairs

10. acidbase conjugate acidconjugate base
HF(aq) + SO
3
2–
(aq) ® F
–
(aq) + HSO
3
–
(aq)
conjugate acid-base pairs
acidbase conjugate acidconjugate base
CO
3
2–
(aq) + HC
2
H
3
O
2
(aq) ® C
2
H
3
O
2
–
(aq) + HCO
3
–
(aq)
conjugate acid-base pairs
acid base conjugate acidconjugate base
H
3
PO
4
(aq) + OCl
–
(aq) ® H
2
PO
4
–
(aq) + HOCl(aq)
conjugate acid-base pairs
Answers: question 18Answers: question 18
(a)
(b)
(c)

11. acid base conjugate baseconjugate acid
HCO
3
–
(aq) + S
2–
(aq) ® HS
–
(aq) + CO
3
2–
(aq)
conjugate acid-base pairs
baseacid conjugate acidconjugate base
H
2
CO
3
(aq) + OH
–
(aq) ® HCO
3
–
(aq) + H
2
O(l)
conjugate acid-base pairs
acid base conjugate acidconjugate base
H
3
O
+
(aq) + HSO
3
–
(aq) ® H
2
O(l) + H
2
SO
3
(aq)
conjugate acid-base pairs
8a)
8b)
11a)
base acid conjugate baseconjugate acid
OH
–
(aq) + HSO
3
–
(aq) ® H
2O(l) + SO
3
2–
(aq)
conjugate acid-base pairs
11b)
For more lessons, visit
www.chalkbored.com