CHEM 120 Week 4 Physical States of Matter Questions and Answers- Chamberlain College Atlanta
Physical States of Matter
WEEK 4
1. Match the term with
... [Show More] the definition:
Particles are tightly packed in a set pattern, with a fixed volume and shape. ---
Particles are close together with no regular pattern of arrangements; has a set volume that will
take the shape of the container it is placed in ---
Particles are well separated with no arrangement, and does not have a set volume but rather
adapts to the entire volume of the container it is placed in ---
Liquid, Solid, Gas
Solid: Particles are tightly packed in a set pattern, with a fixed volume and shape.
Liquid: Particles are close together with no regular pattern of arrangements; has a set
volume that will take the shape of the container it is placed in
Gas: Particles are well separated with no arrangement, and does not have a set volume but
rather adapts to the entire volume of the container it is placed in.
As kinetic energy increases, particles move from a solid to a liquid to a gas state.
2. Oxygen, ------ is inhaled to the lungs, and brought into the blood, which is a ------ .
Our bodies exchange the oxygen for carbon dioxide, which is a ------ . The carbon
dioxide is forced out of lungs by increasing the pressure of the lungs.
Solid, Liquid, Gas
Solid, Liquid, Gas
Solid, Liquid, Gas
Oxygen gas is inhaled to the lungs, and brought into the blood, which is a liquid. Our
bodies exchange the oxygen for carbon dioxide, which is a gas. The carbon dioxide is forced
out of lungs by increasing the pressure of the lungs.
3. Is the quality associated with solids, liquids, or gases, or multiple? Note yes/no for
each.
Solid, Liquid, Gas
Shape is fixed ----
Shape depends on container ----
Volume is fixed ----
Particles touch, with some but not much space between particles ----
Particles move through space easily, with much free space between particles ----
Yes
No
Quality Solid Liquid Gas
Shape is fixed Yes No No
Shape depends
on container No Yes Yes
Volume is fixed Yes Yes No
Particles touch,
with some but
not much
space between
particles
Yes Yes No
Particles move
through space
easily, with
much free
space between
particles
No No Yes
4. Does the property apply to an ideal gas, non-ideal gas, or both?
Ideal Gas ----
Non-ideal Gas ----
Both Ideal and Non-ideal Gas ----
Perfectly elastic collisions , Molecules in constant motion, Collisions can cause chemical
reactions, Molecules have no volume Molecules do have a small volume, No attractions
All gases are in constant motion, and this motion is proportional to their absolute
temperature. In ideal gases, we make three assumptions: they undergo perfectly elastic
collisions, the molecules themselves have no volume, and there are no attractive or
repulsive forces between molecules. In real gases, the collisions can produce chemical
reactions, and the individual molecules do have a small though insignificant volume.
5. Determine if the quality best describes solid, liquid, or gas state of matter.
Can be compressed slightly by moderate pressure -------
Solid, Liquid, Gas
Particles collide but otherwise do not interact ------
Solid, Liquid, Gas
Shape remains rigid ------
Solid, Liquid, Gas
Solids have a rigid shape, fixed volume, with constantly interacting/touching particles.
Liquids can be compressed slightly by moderate pressure, particles flow and move around
each other, and their shape depends on their container. Gases can be compressed with
moderate pressure, their particles collide but otherwise do not interact, and their shape and
volume fills the container.
6. As the number of collisions of an ideal gas increases, which of the following will also
occur?
a. the number of chemical reactions will increase
b. the pressure will increase
c. the gas will become compressed
d. the temperature will increase
e. the gas will become solid
As the number of collisions of a gas increases, the temperature will increase because
temperature is a relative measure of the number of collisions. Additionally, the gas
molecules will collide more with the walls of the container, increasing the pressure. Ideal
gases do not react on colliding, so number of chemical reactions will not increase. This will
expand the volume if the container walls are flexible and will not compress the gas.
7. For ideal gases, the molecules themselves ___________, which is one assumption of
the ideal gas law.
a. will have no collisions
b. will have no volume
c. will have no pressure
d. will have no temperature
The molecules of an Ideal gases are assumed to have no volume themselves; this is an
assumption, as the volume of the molecules themselves is negligible. This allows us to
assume the volume of the gas is the volume of the container without subtracting about the
infinitesimally small volume of the individual gas molecules.
8. Liquids and gasses both…
a. can be poured
b. have molecules that do not touch or interact
c. have perfectly elastic collisions
d. take the shape of the container they occupy
Both liquids and gases take shape of the container: the liquids take the shape of the filled
portion of the container, and gases will take the shape of the entire container.
9. We exhale CO2, a ------. We drink water which is a ------ . Our blood transports
oxygen, a
Solid, Liquid, Gas
Solid, Liquid, Gas
Solid, Liquid, Gas
CO2 and O2 are gases, and water is a liquid.
10. In a hot air balloon, the flame is turned down. What is the result?
a. the volume decreases
b. the temperature decreases
c. the pressure decreases
d. the density increases
As the flame is turned down, the temperature and pressure will decrease. Because this is a
flexible container, the volume will decrease and cause the denisty of the gas to increase.
11. A rigid can of compressed air is used, releasing half of the contents. Which of the
following is the result?
a. the temperature decreased
b. the pressure decreased
c. the volume of the rigid can decreased
The volume of the container will not change, due to the rigid container. The temperature
and pressure will both decrease due to fewer number of collisions when half the volume of
gas is released.
Gas Laws
12. Consider inflating a balloon. As you inflate the balloon, which of the following is
true? Select all that apply.
a. the number of molecules of gas in the balloon increases
b. the gas takes the shape of its new container
c. the volume of the balloon increases
d. the gas collides with the inside surface of the balloon
e. there are fewer gas molecules in the balloon once it is inflated
f. the balloon becomes smaller
As you inflate a balloon, your breath increases the number of gas molecules in the balloon.
These molecules will take the shape of the balloon by colliding with the inside surfaces. At
the end, the volume of the balloon is larger than starting.
Rearrange the formula to solve for the unknown in the following problem:
This question is looking for the new pressure (P2), given an initial volume
(V1), initial pressure (P1) and a new volume (V2) at a constant temperature.
The formula used is Boyle’s law, P1V1 = P2V2. To solve for P2, divide both
sides by V1. This gives the value of
P2 = V1P1V2
13. At a constant temperature, a sample of gas occupies 1.5 L at a pressure of 2.8 ATM.
What will be the pressure of this sample, in atmospheres, if the new volume is 0.92 L?
a. 2.04 ATM
b. 4.6 ATM
c. 0.49 ATM
d. 0.22 ATM
Multiplying P1xV1 and dividing by V2, the answer is 4.56 atm.
Charles’ Law describes the relationship between temperature and volume. Boyle’s law
describes the relationship between pressure and volume. Avogadro’s Law describes the
relationship between volume and number of moles of a gas. Combined gas las describes the
relationship between pressure, temperature, and volume.
When given initial volume and pressure, with no change in temperature, Boyle’s Law will
apply.
When given a scenario involving and changes to volume and temperature under constant
pressure, Charles’ Law will apply.
14. Determine the new temperature in °C for a sample of neon with the initial volume of 2.5
L at 15 °C, when the volume is changed to 3550 mL. Pressure is held constant.
a. 136 ºC
b. 294 ºC
c. 409 ºC
d. 21.3 ºC
d. -252 ºC
Plugging the given values for T1 (15 C + 273 = 288 K), V1 (2.5 L), and V2 (3550 mL = 3.550
L) into the rearranged equation gives a value of T1 of 409 K. To convert back to C, subtract
273: 409 – 273 = 136 C.
15. Match the units to each of the following variables in the Ideal Gas Law
Pressure (P) ----
Temperature (T) ----
Volume (V) -----
Number of moles (n) ----
L, mm Hg, C, mL, F, atm, K, mol, mmo
Pressure (P)= atm. Temperature (T) = K. Volume (V)= L. Number of
moles (n)= mol.
16. Calculate the pressure, in atm, of 0.0158 mole of methane (CH4)
in a 0.275 L flask at 27 °C.
a. 0.13 atm
b. 1.6 atm
c. 0.71 atm
d. 1.4 atm
This question requires the ideal gas law because this looks at multiple
parameters of an ideal gas at one point in time. Temperature must be converted
from Celsius to K. n = 0.0158 mol, V = 0.275 L, T = 27 °C = 300 K, R = 0.08211 Latm/mol-K. Solving for pressure, divide both sides by volume. P = x = 1.4 atm
17. The conditions for STP are:
1 K and 0 atm
273 K and 0 atm
273 K and 1 atm
0 K and 1 atm
STP is standard temperature and pressure. Standard temperature is 0 °C and 1
atm. In Kelvin, this would be 273 K and 1 atm.
18. You have 33.6 L of neon gas at STP. How many moles is this?
a. 22.4 moles
b. 11.2 moles
c. 1.5 moles
d. 752.64 moles
Using the STP equivalency of 1 mole = 22.4 L, we can solve for number of moles
by dividing the given volume, in Liters, by 22.4 L.
19. The relationship of 22.4 L to 1 mole at STP is true for:
a. any gas
b. only noble gases
c. only oxygen gas
d. only halogen gases
This relationship is true for all gases at STP.
20. You are using your hot air balloon to travel. At constant pressure, you
decrease the temperature of the gas by turning down the flame. What do you
expect to happen to the volume of the 400 L balloon as the temperature
decreases?
a. more information is needed to make a determination
b. more than 400 L; as temperature decreases the volume will increase
c. about the same as 400 L; temperature alone does not affect volume
d. less than 400 L; as temperature decreases, volume also decreases
This is an application of Charles’ law: at constant pressure, volume and temperature are
proportional. As temperature decreases the volume will also decrease.
21. A sample of nitrogen (N2) has a volume of 50.0 L at a pressure of 760 mmHg.
What is the volume of gas at a pressure of 1500 mmHg if there is no change in
temperature?
a. 96.7 L
b. 0.010 L
c. 25 L
d. 0.040 L
This question requires Boyle’s law, which involves changes in pressure and
volume at constant temperature. P1 = 760 mmHg, V1 = 50 L, P2 = 1500 mmHg,
V2 = x= 25 L.
22. As you breathe in, your diaphragm ------ , increasing the volume of your lungs
and ------ the pressure in your lungs. As a result, the volume of the lungs will
increase.
Compresses, Drops (expands)
Decreasing, Increasing
As you breathe in your diaphragm will drop (expand), increasing the volume of
your lungs and decreasing pressure in the lungs. This drop in pressure is coupled
to an increase in volume, and air will rush into the lungs. Exhaling is the
opposite, when the diaphragm contracts and increases pressure to expel air by
decreasing volume of the lungs.
23. A sample of helium gas has a volume of 6.5 L at a pressure of 1.11 atm and a
temperature of 25 °C. What is the pressure of the gas in atm when the volume
and temperature of the gas sample are changed to 1850 mL and 325 K,
respectively?
a. 4.25 atm
b. 0.235 atm
c. 0.300 atm
d. 173.5 atm
This question requires the use of the combined gas law and convert volumes to
units of L, pressure to units of atmospheres (done for you), and temperatures to
K. P1= 1.11 atm, V1= 6.5 L, T1= 25 °C = 298 K, V2= 1850 mL = 1.85 L, T2 = 325
K, P2= x= 4.25 atm.
24. A gas in a balloon has a volume of 4.0 L at 0 °C. You move the balloon and
measure the new volume as 6.5 L. What is the final temperature, in °C?
a. -273 °C
b. 171 °C
c. 443.6 °C
d. 0 °C
It is important to convert the temperature to Kelvin in all gas law problems. This
problem looks at a gas under changing volume and temperature, so Charles‘ law
is used. V1 = 4.0 L; T1 = 0 C = 273 K; V2 = 6.5 L; T2 = x = 171 C
25. In the gas laws, the units of the amount of gas (n) is moles, the units of
pressure are ------ , the units for volume are ------ , and the units of temperature
are ------.
mm Hg, atm, mL, L, °C, K
mm Hg, atm, mL, L, °C, K
mm Hg, atm, mL, L, °C, K
The units for pressure are ATM, volume is L, and temperature is K in the Gas
Laws. This is reflected in the gas constant, R, which has untis of L*atm/K*mol.
26. You are inflating a balloon using a helium tank at constant temperature and
pressure. The helium tank ------ the number of moles in the balloon, causing the
volume to ------.
Decreases, increases
Decrease, increase
The helium tank is adding molecules of gas to the balloon as it inflates, increasing
the number of moles as well as the volume.
Rank the following gases by the number of moles they would contain at STP,
greatest to least.
27. 30 L of helium gas, 0.5 moles of oxygen gas, 67.2 L of nitrogen gas.
Nitrogen
Helium
Oxygen
Using the relationship of 22.4 L = 1 mole for any gas at STP, we know that 30 L of
helium gas is the same as 1.34 moles and 3.0 moles of nitrogen gas. This gives the
order from greatest amount to least amount as 3.0 moles nitrogen > 1.37 moles
helium > 0.5 moles oxygen
28. A sample of hydrogen gas occupies 250 mL at 90 mmHg. For a gas sample at
25°C, determine the number of moles of hydrogen present in the sample.
a. 826.4 moles
b. 0.00121 moles
c. 10,962 moles
d. 0.0000912 moles
e. 0.920 moles
This question requires use of the Ideal Gas Law. The volume should be converted
to 0.250 L, the pressure should be converted from 90 mm Hg to 0.118 atm, and
the temperature should be converted from 25 C to 298K. The value for R is
constant: 0.0821 L*atm/K*mol. Rearrange the formula to solve for moles: n =
PV/RT = (0.118 atm)(0.250L) / (298K)(0.0821 L*atm/K*mol) = 0.00121 moles.
Acids-Bases
29. Which of the following solutions would you classify as basic?
a. A solution with a pH of 7
b. A solution with a pH of 6
c. A solution with a pH of 9
d. A solution with a pH of 4
Acidic solutions have pH values below 7 and basic solutions have pH values
above 7.
30. Which of the solutions below do you believe would have the most H+ ions in
solution?
a. A solution with a pH of 4
b. A solution with a pH of 7
c. A solution with a pH of 6
d. A solution with a pH of 9
The lower the pH value, the more H+ ions are present in solution as the lower the
pH value, the more acidic the solution.
31. Which of the following would you expect to be acidic?
a. Ammonia
b. Bleach
c. Baking soda solution
d. Lemon juice
Soda, most fruit juices, and vinegar are just a few of the acids that you may have
seen in your day to day life. Acidic foods and drinks tend to taste sour.
32. Select the acid in this reaction: LiOH + HBr → H2O + LiBr
LiOH, HBr, H2O, LiBrSelect the acid , , , ,
HBr is the acid in this reaction.
33. Select the base in this reaction: HCl + NH3 → NH4+ + ClHCl, NH3, NH4+, ClNH3 is the base in this reaction.
34. Select the acid in this reaction: HBr + H2O → H3O+ + BrHBr, H2O, H3O+, BrHBr is the acid in this reaction.
35. Classify the following reactions:
Strong Acid ---
Weak Acid ---
Strong Base ---
Weak Base ---
LiOH → Li+ + OHHCN + H2O CN- + H3O+ ⇔
NH4+ + OH- NH3 + H2O ⇔
Ca(OH)2 → Ca2+ + 2 OHHBr + H2O → Br- + H3O+
H3PO4 + H2O H2PO4- + H3O+ ⇔
Strong Acid = HBr + H2O → Br- + H3O+
Weak Acid= HCN + H2O CN- + H3O+ & H3PO4 + H2O H2PO4- + H3O+ ⇔ ⇔
Strong Base= Ca(OH)2 → Ca2+ + 2 OH- & LiOH → Li+ + OHWeak Base= NH4+ + OH- NH3 + H2O ⇔
36. Complete the following reaction:
HClH2OLiClLiOH, +, HClH2OLiClLiOH, →, HClH2OLiClLiOH, +,
HClH2OLiClLiOH
Acid, , Base, , Water, , Salt
The Li+ released from the LiOH and the Cl- released from the HCl will from the
salt LiCl.
These reactions always form a water and a salt:
37. Use the measured pH values and H3O+ concentrations of the solutions below to sort from most
basic to most acidic:
pH 12
pH 10
1 x 10-7 M H3O+
1 x 10-6 M H3O+
pH 5
pH 2
1 x 10-1 M H3O+
Acidic solutions have a high concentration of H+ ions while basic solutions have a low concentration of
H+ ions. In terms of pH, the lower the pH value, the more acidic the solution.
38. Which of the following reactions shows a strong acid?
a. in water: NaOH → Na+ + OHb. HI + H2O → H3O+ + Ic. NH4+ + H2O NH3 + H3O+ ⇔
d. NH3 + H2O NH4+ + OH- ⇔
Acids donate a proton in a chemical reaction. Strong acids dissociate completely in water. The correct
answer is: HI + H2O → H3O+ + IWhat is acting as the base in this chemical reaction?
39. H2SO4 + H2O → H3O+ + HSO4-
a. H3O+
b. H2SO4
c. HSO4-
d. H2O
Acids donate H+ ions and bases accept H+ ions. Be sure that for the base you are choosing the
reactant that will accept the H+ ion in the reaction. In this case H2O is the base.
40. Match each pH value with the correct H3O+ concentration.
pH 4 --- 1 x 10-4 M H3O+
pH 5 --- 1 x 10-5 M H3O+
pH 7 --- 1 x 10-7 M H3O+
pH 9 --- 1 x 10-9 M H3O+
pH 12 --- 1 x 10-12 M H3O+
Please note that the inverse of the exponent in the H3O+ concentration gives the pH. As pH goes up
H3O+ concentration goes down and as pH goes down, H3O+ concentration goes up.
41. For the neutralization reaction, what would be the products? Select all that apply.
Al(OH)3 + 3 HBr →
a. 1 AlBr
b. 3 H2O
c. 3 AlBr
d. 3 AlOH
e. 3 OHf. AlBr3
Water and salt are always formed from neutralization reactions. Be sure that the salt, as an ionic
compound, has an overall neutral charge. In this case the reaction is Al(OH)3 + 3 HBr → 3 H2O + AlBr3
42. In the reaction: NH3 + H2O NH4+ + OH-, what is acting as an acid as we go from right to lef? ⇔
a. NH4+
b. NH3
c. OHd. H2O
An acid is the species that donates an H+ ion. Please note that we want to pick the molecule that has
one less H than the compound started with on the indicated side. The acid is NH4+
43. In water, HF dissociates partially in water according to the reaction HF + H2O H3O+ + F ⇔ -. I would
classify this compound as a:
a. Weak base
b. Strong base
c. Weak acid
d. Strong acid
Weak acids donate protons, but do not dissociate completely. The reaction can go both ways.
Remember, “strong” means decisive.
Buffers
44. If I add a drop of acid to a beaker of buffer solution, I would expect the pH of the
solution to:
a. drastically increase
b. stay mostly the same
c. slightly increase
d. drastically decrease
Buffers will resist change in pH, even with the addition of small amounts of acid or base.
45. Which of the below is an example of a buffer?
a. Salt water
b. Lemon juice
c. Tea
d. Contact solution
Buffers contain both an acid and base. Contact solution typically contains a phosphate
buffer to keep contact coatings near the pH of the human eye.
Buffers resist pH change, as in Solutions 1 & 3. This is not always perfect, as we can see in
the case of solution 1.
46. Match each of these acids or bases to their corresponding conjugate acid or base.
H3PO4 ⇒
CH3COOH ⇒
H2CO3 ⇒
OH- ⇒
CN- ⇒
PO43- ⇒
HPO42-
H3PO4
HCN
N3-
H2PO4-
HCO3-
CO3-
H2O
H3O+
CH3-
CH3COOCH3COH
H3PO4 ⇒ H2PO4
-
CH3COOH CH ⇒ 3COOH2CO3 HCO ⇒ 3
-
OH-
H ⇒ 2O
CN-
HCN ⇒
PO4
3-⇒ HPO4
2-
47. When a drop of a strong acid is added to a buffer solution, the pH of the solution would
----because the H+ ion from the acid would be ------.
Increase, decrease, stay about the same
incorporated into, excluded from, the buffer system
A buffer system resists pH change by neutralizing and incorporating small amounts of acid
or base into the system.
48. If you were trying to prepare a buffer with ammonia, NH3, what would be the
substance that you would likely add along with NH3 to prepare the buffer system?
a. NH4+
b. NH2-
c. CNd. NH3+
A conjugate acid/base pair differ from one another by a single H atom. Together, a
conjugate acid/base pair can form a buffer system. You would pair NH3 with NH4+ to form
a buffer.
49. To a small, 50 ml sample of buffer, 100 ml of concentrated strong base solution are
added. You should expect the pH of this solution to:
a. Be fully neutralized
b. Stay the same
c. Increase
d. Decrease
While buffers are able to resist pH change by neutralizing and incorporating small
amounts of strong acid or base, they have limits. In this case, we see a very large amount of
base added to a buffer system, overpowering the buffer effect, so you would expect an
increase in the pH.
50. You are trying to determine which unlabeled solutions are buffers by adding
a few drops of acid to each and measuring the change in pH. Based on the data
below, which solutions would you classify as buffers? Select all that apply.
Number of
drops of
strong acid
added
Solution W Solution X Solution Y Solution Z
0 (initial pH) 6.32 pH 5.44 pH 7.58 pH 8.84 pH
1 6.31 pH 5.00 pH 7.02 pH 8.84 pH
2 6.32 pH 3.14 pH 6.37 pH 8.83 pH
3 6.32 pH 2.21 pH 3.01 pH 8.84 pH
a. Solution W
b. Solution X
c. Solution Y
d. Solution Z
Buffers resist pH change, so we would expect no significant change in the pH of a buffer
solution when a small amount of acid was added, while unbuffered solutions would have a
noticeable decrease in pH value. Solutions W and Z resisted a change in pH and so are
buffers.
The ------- buffer system found in blood, works to maintain the pH of blood at a pH range
between 7.35 and 7.45. If the buffer system is overwhelmed and the pH value of blood goes
above 7.45, ------ would occur.
Carbonate, cyano
Acidosis, alkalosis
The carbonate buffer system in our blood resists pH change, preventing, in most cases
spikes or drops in pH outside of normal values. Acidosis is caused by a drop in blood pH,
while alkalosis is due to an increase in blood pH beyond acceptable levels. [Show Less]