Sadie Moody
February 18, 2008
Chemistry/A Block
Williamson
Problem Set-Chapter 3
1. Physical properties are properties of elements or compounds that can be
observed or measured without changing their compositions. Examples of
physical properties are color, density, odor, melting point, boiling point,
etc. Pure substances are also defined as physical properties because
substances have uniform and unchanging compositions; therefore their
physical properties cannot be altered either. They are defined BY their
physical properties… not as physical… for example – water has a
boiling point of 100.0oC. Chemical properties are properties that allow
substances to combine or change into one or more substances. For
example, copper forms a green carbonate compound when it comes in
contact with moist air.
2. Intensive properties are properties that do not depend on the amount of
matter present. For example, color, density (the mass divided by a
substances volume), melting/freezing points, etc. Extensive properties are
properties that do depend on the amount of matter present. Examples of
extensive properties include mass, volume, length, etc.
3. The molecules in solid lead would be present in a definite shape and
volume – the molecules would be arranged in a close, yet orderly manner.
In the solid phase, the molecules are slow moving because they are more
compact. The molecules in molten lead would take the shape of its
container and the molecules would still move slowly, but they would not
have a specific arrangement. good
Solid Lead Molecules
Molten Lead Molecules
4. Steam is present in the gaseous phase of water. Most people refer to
steam when they’re boiling a pot of water and the hot vapor mixes with the
colder air above (resulting in a white “mist”). Another example is when
there appears to be nothing coming out of the spout of a kettle and really
that “nothing” is steam. Water is present in the liquid state of H2O. Steam
is something that is hardly noticeable because it’s in a gaseous state;
however in the liquid state, water is something that you can see even
though it’s colorless. Water takes the shape of container it occupies;
however its properties cause it to curve, etc. – so it’s not a complete
cylindrical or rectangular shape.
Liquid Water Molecules
Steam Molecules
even farther apart
5. Many people confuse the term gas for vapor – even though they are
closely related they do not mean the same thing. Vapor is a term that
refers to the gaseous phase of a substance that is a solid or liquid at room
temperature.
A. Steam is a vapor because at room temperature water exists as a liquid.
B. O2 is a gas because it cannot exist in the solid or liquid state.
C. CO2 is a gas because it cannot exist as a solid or liquid.
D. Mercury that has boiled is a vapor because it exists in other states.
6. The initial substances in a chemical reaction are called the reactants.
Chemical reactions involve chemical change and yield at least one new
product. During chemical reactions, individual molecules change their
structure as they interact with different substances – some products may
result with the same number of atoms but different structures. You must
observe that the product(s) have different properties than the reactants;
from this observation you can conclude that a chemical reaction took
place. A chemical reaction always produces new products (meaning
changes in properties).
7. B
8. A
9. C
10. A
11. B
12. A
13. Three States of Matter Drawing (See Other Page)
14. A physical change is a change in which a new substance is formed. A
chemical change results in the formation of one or more new substances.
A physical change is reversible, whereas a chemical change is not.
Actually – chemical reactions are reversible, but they are often
harder to reverse than a physical change. Physical changes can be
hard to reverse too… tearing a piece of paper into small pieces is a
physical change, because the material is still paper… For example,
you can freeze water and you can melt ice (physical changes) – however
you cannot burn wood and then get the wood back. But the ash, CO2,
and water that are produced can go back into forming other trees…
15. Because mass remains constant during a chemical reaction (meaning the
mass of the reactants must equal its products), energy cannot be created
nor destroyed, however its form can change. The universe has a fixed
amount of energy however, it is supplied in diverse ways – there’s not just
one source for energy. That’s why energy is changeable through
chemical reactions. You focused on energy in the response, mass
does the same – transferring from one substance to another…
16. A. (5.00g hydrogen + 39.7g oxygen) = 44.7 grams of water.
B. (50.0g bromine + 5.15g aluminum) = 55.15g aluminum bromide and
aluminum. (55.15g – 4.25g bromine) = 50.9 grams of aluminum
bromide.
C. (4.12g magnesium oxide – 2.43g magnesium) = 1.69 grams of
oxygen.
17. B
18. A
19. B
20. D
21. C
22. Condensation:
Vaporization:
Vaporization:
Freezing:
Melting:
Sublimation:
Deposition:
23. A homogeneous mixture has the same uniform appearance and
composition throughout (definite, consistent properties). A heterogeneous
mixture consists of visibly different substances or phases.
24. A. Filtration
B. Distillation
C. Crystallization
D. Chromatography
25. Tincture
26. Aqueous solution
27. Amalgam
28. A. Solvent: Water Solute: Salt
B. Solvent: Water Solute: Acetic Acid (Vinegar) vinegar is dilute
acetic acid… it is diluted with water… pure acetic acid is VERY nasty
stuff…
C. Solvent: Air
Solute: Water
D. Solvent: Silver Solute: Mercury
E. Solvent: Iron
Solute: Carbon
29. A. Homogeneous
B. Heterogeneous x homogeneous – the salt is totally dissolved in the
water forming a uniform mixture
C. Homogenous x heterogeneous – there are blueberries and batter
and butter…
D. Heterogeneous
30. When you open a can of soda, it changes from a solution to a
heterogeneous mixture because the contents of the can are being
exposed to other elements/compounds like oxygen, water vapor, etc.
Also, the contents in the can are under high pressure when the can is not
opened and once you open it, the pressure inside the can changes –
therefore altering the phase or consistency of the solution. The CO2 that
was under pressure in the solution, comes out as bubbles.
31. When 50.00 mL of ethanol mix with 50.00 mL of distilled water, their total
volumes do not add up to a 100.00 mL solution because of their molecular
arrangements. Water has a unique molecular arrangement and it differs
from the arrangement of ethanol molecules, therefore they do mix
uniformly. Water molecules have pockets that allow some ethanol to get
in therefore, the volume is usually less than the predicted volume.
Procedural Essay # 42
Not much of an introduction/hook…
Several separation techniques were used to obtain the ingredients in
Italian dressing (water, vinegar, oil, and oregano). Because oil is not soluble in
water, the decanting process was used (pouring a solution from a container,
leaving the precipitate or sediment at the bottom of the container). The Italian
dressing was placed in one beaker, and a separate beaker was used for the
separation process. The oil formed a layer of its own due to its insolubility so it
was easily removed from the rest of the mixture. (How about density?) This
was the most efficient way to separate the oil from the remaining ingredients –
this was done carefully because the consistency of oil can be hard to manage.
Once the oil was separated from the Italian dressing, it was placed in a container.
Considering vinegar and water are both liquids, and oregano is a solid, the
dressing underwent filtration (the act of separating solids from liquids). The
beaker containing these three ingredients was prepared for filtration. A filter was
folded properly (into quarter’s) and placed in a filter funnel, which was placed in
the ring of a ring stand. An empty beaker was placed directly underneath the
ring stand and ring. The dressing was poured slowly into the filter (making sure
that the filter did not overflow with liquid). All of the mixture was filtered so the
oregano would remain in the paper filter. Once all of the mixture was poured
from the beaker, the oregano remained in the filter to dry – it was then placed in
its own container. nice
Because the remaining substances formed a homogenous mixture, the act
of distillation would have to take place. A particular set- up including a round
bottom side-arm flask, a condenser, thermometer, hot plate, empty beaker,
condensation tube, a sink, and a faucet was used to perform the remainder of the
experiment. The vinegar and water mixture was placed in the round bottom sidearm flask, along with the thermometer. The hot plate was turned on as a heat
source. The faucet was also turned on so cold water could enter the laboratory
set-up (particularly the condensation tube). An empty beaker was placed
underneath the opening of the condensation tube. The mixture in the flask was
heated just so the water would distillate (where the vinegar would not reach its
boiling point). Note: this was done with very careful precautions as the boiling
points of both substances are very close to one another. The boiling point of
water is about 100°C and the boiling point of vinegar is about 100.6°C –
therefore the heat of the mixture in the flask was
watched carefully, so the temperature did not reach
more than 100.0°C. ok – acetic acid is one liquid in
the vinegar, the water is the other – acetic acid
boils at 118oC.
Through the act of distillation, the vinegar
remained in the round bottom side-arm flask and the
water was drawn into the empty beaker through the
condensation tube. The act of distillation has some
limitations, considering it involves a heat source, and
it’s could be hard to manage the temperature of the mixture when both
substances have a similar boiling point – however this is a good way to separate
homogeneous mixtures like vinegar and water. Once the process was done, the
separate solutions were placed in containers.
Diagram From:
http://blog.crispen.org/images/distillation.jpg
13. Three States of Matter
Solid
Liquid
Gas