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Science 30 Unit B: Chemistry
Acids, Bases and Protons
Name: ______
Date:
______
Properties of Acids
1) ………………………………………..
4) ………………………………………..
2) ………………………………………..
5) ………………………………………..
3) ………………………………………..
6) ………………………………………..
Properties of Bases
1) ………………………………………..
4) ………………………………………..
2) ………………………………………..
5) ………………………………………..
3) ………………………………………..
6) ………………………………………..
7) ………………………………………..
Fun Facts!
Both acids and bases are _______________ (can dissolve materials), particularly to living tissue.
Acids are also very corrosive with most ___________.
Properties of Neutral Compounds
1) ………………………………………..
2) ………………………………………..
3) ………………………………………..
Strong Acids/Bases- Acids or bases which have these properties to a greater extend (especially
_____ and _______________) are classified as strong acids and strong bases.
But why are acids "acidy"? What makes an acid act like an acid?
All acids seem to contain ____________.
Fun Fact! A hydrogen ion is really just a __________, the basic unit of positive charge in an
atom.
In general, an acid gives away a proton to produce
hydronium.
Acids are proton _______________.
Fun Fact! ___________________ is what makes acids "acidy". We will study this more later on.
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By the same token, bases (like the carbonate ion
above) are proton ______________. They take
protons from water to form the hydroxide ion, OH-.
Fun Fact! _____________ is what makes bases "basic". We will study this more later on.
Acid Deposition -describes how acids are deposited in the ____________________.
There are two types of acid deposition:
Wet Deposition
Dry Deposition
*In Alberta, most deposition is __________ deposition.
There are 3 main elements produced by human actions that lead to acid deposition.
Carbon
Found in: ________________ such as natural gas (CH4), coal (C) or gasoline.
Gets into the atmosphere: through burning in a hydrocarbon ________________.
Product that forms Acids: ____________________ (forms carbonic acid)
Sulfur
Found in: hydrocarbons such as _________ ______ (H2S is present), or _________ (C).
Gets into the atmosphere: through burning to produce electricity or ____________.
Product that forms Acids: ____________ (forms sulfurous acid) and _____________ (forms
sulfuric acid)
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Fun Fact! H2S gas is often mixed in with __________ _____ when mined: the result is called
sour gas.
In the refining process, the gas is sweetened to remove the H2S. The H2S and some natural gas is
then flared in the reactions just shown.
Fun Fact! In the refining of bitumen, _________ is also produced. This elemental sulfur is
stockpiled in places like Fort McMurray.
Nitrogen
Found in: _______ (about 70% of ______ is nitrogen)
Gets into the atmosphere: through high __________________ produced when burning fossil or
other fuels.
Product that forms Acids: _____________ _______________ and ___________ (form nitric
acid)
Acid/Base Reactions
Follow these 5 steps to write an Acid-Base Reaction:
1. Find the two solutions that are reacting.
ex) Write the neutralization reaction between nitric acid and the hydroxide ion.
The solutions reacting here are nitric acid and the hydroxide
ion.
2. Identify the acid and base.
3. Write the reactants (left hand) side of the equation.
Fun Fact! The (aq) stands for "aqueous", a state of matter like
solid, liquid or gas. All acids and bases are aqueous, so you
will write this state for all of your reactants.
4. Find the conjugate pair of the acid and base.
5. Write the conjugate forms on the products side of the
equation.
Fun Fact! Note how the acid is a proton donor and the base is
a proton acceptor.
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ex) Write the chemical reaction between phosphoric acid and the ammonium ion.
ex) Write the chemical reaction between sulfuric acid and water.
Practice: Acid and Base Rxn Worksheet
pH and
Acid Strength
pH - It is essentially a new way to describe the concentration of hydronium in acids.
Concentrations of hydronium in acids varies wildly from very small (i.e. 10-13 mol/L) to quite
large (0.01 mol/L). The pH scale puts this wide range of measurements on one convenient scale
from about 1 - 14.
This new scale is produced using a mathematical tool called the logarithm.
How to convert a [H3O+] into a pH:
The formula for calculating pH is as follows:
Where [H3O+] = the concentration, in mol/L, of hydronium.
Fun Fact! This formula is on page 11 of your data booklet.
ex) Given a [H3O+] = 6.7 x 10-8 mol/L, calculate pH.
*In order to obey the laws of sig-digs,
you should record as many digits after
the decimal in your pH as you have
significant digits in your original
concentration.
pH = -log[H3O+]
pH = -log[6.7 x 10-8]
pH = 7.1739...
pH = 7.17
ex) A solution has a hydronium ion concentration of 4.7 x 10-11 mol/L. What is the pH of the
solution?
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How to convert a pH into a [H3O+]:
*Note that because pH has no units, you will have to tag on the mol/L yourself on your final
answer.
ex) A solution has a pH of 5.3. What is the hydronium concentration?
*Note: there is one number after
the decimal place, so you must
have one sig-dig in your final
answer.
[H3O+] = 10-pH
[H3O+] = 10-5.3
[H3O+] = 5 x 10-6 mol/L
ex) What [H3O+] is a pH of 10.33?
Because the pH scale uses base 10 logarithms, an increase of 1 in pH = 10x increase in
concentration.
ex) A can of Coca-cola has a pH of about 3. The pH of battery acid is 1. How many times more
concentrated is the battery acid than the Cola?
Measuring pH
Indicators change colour when the solution they are in reaches a particular point. A table of
indicators is on page 12 of your databooklet.
ex) A solution is tested with 3 different indicators. The results are shown below.
Estimate the pH of the solution.
Fun Fact! First Nations people coloured their clothing with natural indicators, then used natural
acids to adjust the colour to their liking.
Practice: page 183 #22 and 23
page 186 #26-28
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Acid Deposition in
Ecosystems
Acid Deposition: when _________ particles that form _______ get into water supplies ( _____
deposition) or the soil/air ( _______ deposition).
Changes to abiotic Factors
Abiotic factor: the ____________ part of the environment.
ex) _________, ____________, ___________, ____________
When acid deposition occurs, the pH of soil and water _______________.
This can also cause leaching, the process by which __________ (like aluminum and mercury)
are dissolved from soil/rocks and move into soil or water supplies.
Fun Fact! Most soil naturally contains traces of metals, but those metals are not _____________
by regular rain water so are left undisturbed.
Some of these changes can be controlled by the environment. For example, much of the soil in
Alberta contains ____________ (CaCO3) left over from coral reefs from the prehistoric oceans
that covered Alberta. The CO3- ion acts as a base, ____________ some of the acids deposited.
Fun Fact! Soil that is basic is said to be ___________.
ex) Complete the reaction between the acid (H3O+) and the carbonate ion (CO3-(aq)).
H3O+ + CO3- →
The ability for soil to neutralize a small amount of acid is called _____________.
Soil with more calcium carbonate have a higher buffering capacity, soils with less have a lower
buffering ____________.
Changes to biotic Factors
Biotic factor: ____________ part of the environment.
ex) ____________, ___________, __________
1. Increased _____ of water supplies: organisms are very sensitive to acidity and even a small
change can cause problems.
2. Damage to plant life: this destroys the _______ level of the food chain.
3. Uptake of toxic __________
Biomagnification- As toxic metals move up the food chain, they become ________ in organisms.
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Acid-Base Titrations
A titration is a lab procedure used to determine the concentrations of solutions.
We determine concentration by adding a carefully measured amount of a known solution (called
the titrant) to a solution with an unknown concentration (called the sample). The analysis of this
lab helps to determine the concentration of the unknown solution.
The titrant (known concentration) goes in a burette.
The sample (unknown concentration) goes in an Erlenmeyer flask.
We titrate (add titrant) until we get to a point where some sort of
change takes place (i.e. indicator colour change). This point is called
the endpoint.
The volume of the known chemical will be important because it will
allow us to determine the concentration of the unknown chemical.
We are able to do this because the number of moles of each chemical
will be equal at the equivalence point.
In the analysis of a titration, we determine the concentration of the unknown using some simple
math. You will use the concentration formula:
Fun Fact!
In Science 30, we will only perform strong monoprotic acid/base titrations, so the coefficient of
acid to base is always 1:1.
Let's look at a reaction between sodium hydroxide (base) and hydrochloric acid (acid).
ex) 10.00 mL samples of a 0.150 mol/L
solution of NaOH are taken and titrated with
HCl of an unknown concentration. Using the
data below, what is the concentration of the
HCl(aq)?
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Q) Why is there an initial and final burette reading?
A) When you fill up a burette, you don't have to fill it exactly to the top. You can just throw in
enough to get it close to the top and record this as the initial volume. Then, if you record the final
volume and subtract the two, you'll know how much of the titrant you added.
Q) Why are there 4 trials? And why are the numbers different for each trial?
A) We repeat the trials to get accurate results. The numbers are different because it is difficult to
measure out exactly the same volume of unknown each time. We will be taking the closest
volumes and averaging them later in the analysis.
Q) What does the indicator colour have to do with anything?
A) The colour change in the indicator tells us when to stop adding titrant. This indicator changes
colour around pH 3.5. At this pH, all of the weak base has reacted with the acid.
Step 1: List the info given in the question. Convert everything to litres.
Step 2: Using the table, determine the volume of titrant (HCl) added in each trial. Take the
average of the closest values. If any value is far off the others, omit it.
Step 3: Using the equation, determine the number of moles of the known chemical.
Step 4: This number of moles is the same as the number of moles for the unknown. Use the
equation a second time to solve for the volume of the unknown.
ex) What is the concentration of potassium hydroxide?
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ex) What is the concentration of this barium hydroxide solution?
Practice: Titration Analysis WS
Learning from Acid Deposition
Reading Assignment:
Read page 222 - 234 and answer questions 3-6
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