1. In the picture a meniscus is viewed on a graduated cylinder.
Volumes are measured in milliliters and each tick mark represents a
single milliliter (ml). Report the volume in milliliters (ml). Remember
to report numbers using the number of significant figures allowed by
the scale on the device. If the mass of the liquid in this graduated
cylinder was recorded to be 25.46 grams, what would the density of
the liquid be in grams/milliliter? Remember to report with the
number of significant figures allowed by the measuring device.
2. A skier gets off of a chair lift at the top of a hill, which of the following are true? (circle one)
a. The skier has a large potential energy because the lift used
energy when it pushed against gravitational forces to carry the
skier up the hill.
b. When the skier skis down the hill the potential energy due to
the gravitational field will be converted to the kinetic energy of
motion.
c. The skier has a large potential energy because the lift used
energy when it pushed against electric forces when it carried
the skier up the hill.
d. Skis are the rollerblades of the snow.
e. a and b are correct
3. If a positive and a negative charge have become stuck together by their attractive electric forces
and you want to separate them, what must you use to push against the electric forces that pull
them together? (choose the best answer)
a.
b.
c.
d.
Ions
Molecules
Energy
A tow truck
4. When the charges in the above question have been separated from each other they are at a
higher/lower (circle one) potential energy because of their positions in each others
electric/magnetic/gravitational (circle one) fields. If they are released and allowed to approach
each other, energy will be released in the form of ______________.
a. Combustion
b. Electromagnetic Radiation (light)
c. Mass
d. Gravity
5. Hydrogen (H2) and Oxygen (O2) combine to form water according to the equation 2H2 + O2 →
2H2O. Hydrogen and Oxygen are accurately described by the term _____________.
a.
b.
c.
d.
e.
Element
Compound
Diatomic Molecule
A and C are correct
B and C are correct
6. Water is accurately described by the term _______________.
a.
b.
c.
d.
e.
Element
Compound
Molecule
Mixture
B and C are correct.
7. In a hydrogen atom, hydrogen’s single negatively/positively (circle one) charged electron is held
to the rest of the atom by the negatively/positively (circle one) charged ____________ in the
nucleus.
a.
b.
c.
d.
Proton
Neutron
Electron
Voltron
8. In the formation of water an Oxygen molecule approaches a Hydrogen molecule and electric
fields from the positively charged nucleus of one of the Oxygen atoms pulls on an electron
belonging to one of the Hydrogen atoms. The electric field of the Oxygen nucleus pulls on the
electron more strongly than the field of the Hydrogen nucleus does and so the electron moves
toward the Oxygen nucleus. When this happens, potential/kinetic/kharmic (circle one) energy
stored in the electric/magnetic/gravitational/strawberry (circle one) field is released as
______________.
a.
b.
c.
d.
Electromagnetic radiation (light)
Mass
Combustion
Fire
9. Given your answer to the previous question, which of the following diagrams correctly depicts
the relative energies of the products and reactants in this chemical reaction? Hint: if energy is
released, the molecules no longer have that energy stored in them.
a.
b.
10. The above reaction between Hydrogen and Oxygen is an example of a ______________ change.
a. Physical/state
b. Chemical/molecular
c. Regime
d. Atomic
11. A candle is combusted below a tin can and the energy released by combustion is absorbed by
100g of water in the can. The waters temperature rises from 800C to 1000C and after that the
water begins to boil…
a. If one gram of wax is combusted in the process of heating the water to its boiling point,
what is the heat of combustion of the wax in joules/gram? Assume all energy is
transferred to the body of water. (For this problem do your calculations on a separate
sheet of paper and attach that paper to your exam. Show All of Your Work and
remember to check that your units are correct!)
b. As the water is being heated, what physical effect is the absorbed energy having on the
water molecules?
i. The energy is acting to decrease the water molecules kinetic energy by slowing
down their motion and decreasing the strength of their collisions.
ii. The energy is acting to increase the water molecules kinetic energy by speeding
up their motion and increasing the force of their collisions.
iii. The absorbed energy has no effect on the water molecules.
iv. I’m all out of energy.
c. At the boiling point, water molecules begin to leave the liquid state and enter the gas
state. When this happens, what must be true? (choose the best answer)
i. Water molecules are no longer attracted to each other and so they are no
longer held together in the liquid state.
ii. Water molecules experience repulsive forces between each other and are
forced out of the liquid state and into the gas state.
iii. The increased force of collisions between water molecules (due to their
increased kinetic energy) has become strong enough to overpower the electric
forces that would otherwise keep the water molecules stuck together in the
liquid state.
d. The mutual attraction between two water molecules is largely due to what kind of
attractive force?
i. Polar forces. The positively charged end of one water molecule is attracted to
the negatively charged end of another water molecule creating a strong
attraction.
ii. Non-polar forces. The electron cloud of one water molecule repels the electron
cloud of another water molecule temporarily exposing the positively charged
nucleus and creating a weak attraction.
e. In your own words explain Oxygen’s role in making the attractive forces between two
water molecules possible.
12. Water is a molecule composed of two hydrogen atoms bound to an
oxygen atom. The mass of a water molecule is the sum of the
masses of its subatomic particles (protons, neutrons and electrons).
A hydrogen atom is composed of one proton and one electron and
the oxygen atom is composed of eight protons, eight neutrons and
eight electrons. The masses of the subatomic particles are as
follows… Proton mass = 1.673 x 10-24 grams. Neutron mass = 1.675
x 10-24grams. Electron mass = 9.11 x 10-28grams. Calculate the
density of the water molecule in grams/ml. Assume that a water
molecules total volume is the sum of the volumes of three spheres,
two for each hydrogen atom (radius = 0.110 nanometers) and one
for the oxygen atom (radius = 0.152 nanometers). The volume of a
sphere is (4/3)π(radius)3. Useful conversion factors: 1 x 109
nm/Meter, 1Meter/100cm, 1cm3/ml. (Show ALL Work on a separate sheet of paper. Remember
to check units).
13. If you have calculated the density of the water molecule
correctly you will notice that the density of a single water
molecule is greater than the density of liquid or solid water.
Explain why this is. Hint: look at the following image for a
depiction of water in the liquid state.
14. When Rutherford was investigating the properties of the atom he designed an experiment
where he fired alpha-particles (a positively charged particle with two protons and two neutrons)
at a thin piece of gold foil. He was surprised that the majority of the particles passed right
through the foil. He was even more surprised that some of the particles bounced right back at
him! What part of the atom were the alpha-particles colliding with and what subatomic
particles compose this part of the atom? Why does it make sense that a collision of an alphaparticle with this part of the gold atom would deflect the particles path? Would the charge on
this part of the atom tend to attract or repel an alpha-particle? Why did most of the alphaparticles pass right through the gold foil and which subatomic particles occupy the space they
passed through? Would you expect a collision of an alpha particle with one of these subatomic
particles to result in a deflection of the particles path? Why?
15. The most abundant form of Oxygen (16O) has 8 protons and 8 neutrons and 8 electrons. A stable
isotope of Oxygen is 18O, how many protons, neutrons and electrons does this isotope have?
16. This isotope of Oxygen will behave electrically like any other Oxygen atom. What is the charge
of the ion that this atom will tend to form and how many protons, neutrons and electrons will it
have?
17. What will be the empirical formula of the ionic compound formed when an Oxygen atom reacts
with Potassium?