1) HW #6 pg. 628 #18-19
2) Take Home Lab #5 due Wed. 12/2
Quark
Quark in his Halloween costume
Monday, November 30, 2015
Friday, November 20, 2015
Reaction Rate Challenge
Reaction Rate Challenge
Objective: To
work with your partner to devise three different experiments to change the
reaction rates via concentration, temperature and surface area. For each section of the lab, you will need to
see Ms. Cotta before you can proceed to the next part.
Pre-Lab Question:
1. Explain for each factor how you
could speed up and slow down a reaction for each factor.
a.
concentration:
in
order to speed up we will:
in
order to slow down we will:
b.
temperature:
in
order to speed up we will:
in
order to slow down we will:
c.
surface area
in
order to speed up we will:
in
order to slow down we will:
Procedure:
1. Write out the steps of how you are testing your different factors and how you are changing the conditions when you experiment.
1. Write out the steps of how you are testing your different factors and how you are changing the conditions when you experiment.
Post-Lab Questions: (pg. 99, 100 ,102)
1) Draw a before and after drawing
for each of your three experiments. Make sure to label the drawings with which
factor you used and if it was speeding up or slowing down. Your drawings should show the molecules that
we cannot see and what is happening to them.
2) Were there any of your experiments
that did not work out the way that you expected? Explain why you think it was
the case?
3) Imagine you are in a science
laboratory and producing hydrogen gas from the reaction of zinc metal and
hydrochloric acid. The reaction is
occurring too fast for you to collect all the hydrogen gas. Name two different ways you would slow it
down.
Take Home Lab #5
Take Home Lab #5: Lifting and Ice cube with a String
Question: How does salt affect ice?
Safety: Dispose of all materials when
finished. Do not consume any of the materials used in this activity. Clean up
any spills immediately.
Materials: Ice cube, water, string,
salt, sugar, one other soluble substance
Procedure: In this lab, you will be
shown a discrepant event (an action that does not make much sense). Then you
will be asked to try to figure out how it worked. You may use your book,
information given in class, and the internet to figure out your answer.
Remember that the internet may contain a lot of elementary and incorrect
information. If you use the internet, be careful to analyze what you read and
only depend on high school-level and well-known websites. If the website is the
UCLA chemistry website, it is probably trustworthy. If it is little Johnny’s
third-grade science fair project website, it probably is not reliable.
1. Put one
large ice cube in an almost full cup of water so that it is near the top of the
cup.
2. Lay a
string across the top of the ice cube. Coil it in circles if possible.
3. Sprinkle
salt on the string and ice cube and wait 10 seconds.
4. Now lift
the ice cube out of the water.
5. Try this
procedure again using sugar and at least one other soluble substance. (Such as
kool aid, baking soda, powder laundry detergent) Tell whether each one had the
same effect on the ice as the salt.
Wrap-Up
1. Write a paragraph describing what
occurred when you used the salt, sugar and what other substance (name the
substance when explaining) you used and attempted to lift the ice cube.
2. Write a 200-word (1/2 page)
explanation for how this event works. Try to use some of the following terms in
your explanation: freezing point depression, temperature, heat, heat of fusion,
melting and freezing.
HW #5 for 11/30
1) HW #5 for 11/30 pg. 606 exer. 17.1, pg. 610 exer 17.3 (yellow boxes), pg. 611 #1, 5
2) Take Home Lab #5 will be due Wednesday when we get back
3) Finish labs in composition book, all are posted on website.
2) Take Home Lab #5 will be due Wednesday when we get back
3) Finish labs in composition book, all are posted on website.
Monday, November 16, 2015
Friday, November 13, 2015
Tuesday, November 10, 2015
Take Home Lab #4
Take Home Lab #4: Molecular Shape
Question: How does the shape of a
molecule affect its chemical properties?
Safety: Clean up any spilled or
splashed water when finished to avoid slipping.
Materials: Comb, balloon, or other
source of static electricity; water faucet.
Procedure: Because oxygen has six
valence electrons (Figure 1), it bonds with two hydrogen atoms, each having one
valence electron. But there are two different configurations that this
combination could make. The hydrogen atoms could line up across from each other
(Figure 2), or they could arrange themselves next to each other (Figure 3).
The way to tell which
configuration the water molecule actually takes the form of is to test its
properties. In the configuration in Figure 2, the hydrogen atoms are slightly
positive because the oxygen atom is pulling on the electrons harder than the
hydrogen atom. Therefore, each end of the molecule is positive (nonpolar
covalent) and water would not be affected by its static electricity. In the
configuration in Figure 3, the hydrogen atoms are both on the same side and two
pairs of electrons (negative) are on the other side. This would make the water
molecule have poles like a magnet (polar covalent), and it would be affected by
static electricity.
1. Test
whether a thin stream of water from a faucet is affect by static electricity or
not.
2. Static
electricity can be generated in many ways. Be sure that the object is charged
by showing that hair is attracted to it.
a. Rub a balloon on your hair or
a pet’s hair.
b. Comb your hair with a plastic
comb.
3. Put the
comb or the balloon next to (but not touching) a slow running water faucet and
observe what occurs.
4. Use the
comb or balloon to see if it will affect small pieces of paper, salt, pepper,
small scraps of aluminum foil and sugar.
Record your observations.
Post-Lab Questions:
1. What happened, if anything, when you
brought the static electricity near the stream of water?
2. Which figure (2 or 3) shows the
actual structure of water?
3. Molecules that have a partial
positive charge on one end and a partial negative charge on the other end are
said to be polar. Molecules that have the same charge on both ends are called
nonpolar. Is water polar or nonpolar?
4. Examine the electronegativities
(from pg. 403 in textbook), do the values for hydrogen and oxygen support your
answer for #3?
5. Fill in the data table for your
results from #4 above.
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Substance:
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Attracted?:
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Polar or nonpolar?:
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Paper
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Salt
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Pepper
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Aluminum Foil
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Sugar
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Friday, November 6, 2015
Ionic vs Covalent Properties Lab
Ionic vs. Covalent Properties
Objective: To
measure and observe the properties of various compounds in order to group them
into categories of ionic and covalent.
After grouping the compounds, to analyze which of the properties were
most and least helpful to organizing the compounds.
Background:
Chemical compounds are
combinations of atoms held together by chemical bonds. These chemical bonds are
two basic types: ionic and covalent. Ionic bonds result when one or more
electrons from one atom or a group of atoms are transferred to another atom.
Positive and negative ions are formed. In covalent compounds, the electrons are
shared by the bonded atoms.
The
physical properties of a substance such as melting point, solubility, and
conductivity tell us a lot about the type of bond in a compound. In this
laboratory, you will conduct tests on the properties and collect data enabling
you to classify compounds as ionic or covalent.
Pre-Lab Questions:
1. Explain
ionic bonding and covalent bonding in terms of the electrons in each type of
bond.
2. Explain the
differences in properties between ionic and covalent compounds.
Procedure:
Make complete observations for each step and record in your data table.
1. Data Table
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Compound:
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Description:
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Melting Point:
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Solubility with ethanol:
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Solubility with water:
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Conductivity:
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Calcium
chloride
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Sucrose
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Potassium
iodide
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Copper sulfate
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Citric acid
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Salicylic
acid
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A. Melting Point
1. Measure 1 g of each compound and
place in an aluminum foil boat.
2. Heat over a candle for a two (2)
minutes and record how it reacts to the heat and notice the amount of time to
record a change in the substance if there is one.
3. If a substance melts, remove it
immediately.
4. Record data to which substances
melt and do not and any other details.
B. Solubility with Ethanol
1. Place 0.3 g of each compound and
place in a test tube.
2. Add 10 drops of ethanol to each
test tube.
3. Shake it for approximately 2
minutes.
4. Record the observations in the
data table and repeat for remaining compounds.
C. Solubility with water
1. Repeat steps 1-4 from above for
solubility with ethanol but use water instead of ethanol.
2. Pour your liquid into a well of
your testing tray after you have finished shaking it.
D. Conductivity
1. Place your wires of the
conductivity into your substance.
2. Make sure that your wires do not
cross.
3. Record if the lightbulb lights up
and how brightly.
Post-Lab Questions:
1. Using each
of the properties that you tested separate the compounds into two groups:
A. Melting point
--Compounds that melted and compounds
that did not melt
B. Solubility with ethanol
--Compounds that dissolved in ethanol
and compounds that did not dissolve
C. Solubility with water
--Compounds that dissolved in water
and compounds that did not dissolve
D. Conductivity
--Compounds that conducted
electricity and those that did not conduct
2. Separate
the compounds into two groups: Ionic and covalent
*(Hint: if not sure, look at the elements that
are in the compounds)
3. Describe
the general physical properties that you observed for ionic compounds.
4. Describe
the general physical properties that you observed for covalent compounds.
5. Using your
data which physical property best separated your compounds into ionic and
covalent?
6. Using your
data which physical property was least helpful to separate your compounds,
explain why.
7. List the
physical properties you would expect these compounds to have:
a.
acetic acid HC2H3O2
b.
methane CH4
c.
magnesium oxide MgO
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