Lecture Quiz
Name_________________________________
25 points
Lab Section: 11:00
12:30
2:00
1. You pulverize a 200. mg tablet of vitamin C and mix it with 100. mL of distilled water. You extract a
10.0 mL sample and dilute this to 50 mL with distilled water. You now add a starch indicator and find
you need to add 15.3 mL of iodine solution to get a permanent color change.
You now perform this experiment with orange juice. You take 20.0 mL sample of orange juice and dilute
it to 50.0 mL with distilled water. You add the starch indicator as before and find you need to add
10.1 mL of iodine solution to this sample to get a purple color.
a. How many mg of vitamin C are in this sample of orange juice? (2)
𝟏𝟎.𝟎 𝒎𝒈 𝑽𝒊𝒕𝒂𝒎𝒊𝒏 𝑪
𝟏𝟓.𝟑 𝒎𝑳 𝑰𝒐𝒅𝒊𝒏𝒆
=
𝟔.𝟔𝟎 𝒎𝒈 𝑽𝒊𝒕𝒂𝒎𝒊𝒏 𝑪
𝟏𝟎.𝟏 𝒎𝑳 𝑰𝒐𝒅𝒊𝒏𝒆
b. How many mg of vitamin C are in an 6.0-oz (177 mL) serving? (2)
𝟔.𝟔𝟎 𝒎𝒈 𝑽𝒊𝒕𝒂𝒎𝒊𝒏 𝑪
𝟐𝟎.𝟎 𝒎𝑳 𝑱𝒖𝒊𝒄𝒆
=
𝟓𝟖.𝟒 𝒎𝒈 𝑽𝒊𝒕𝒂𝒎𝒊𝒏 𝑪
𝟏𝟕𝟕 𝒎𝑳 𝑱𝒖𝒊𝒄𝒆
c. How many milliliters of juice do you need to drink to obtain the RDA of 60 mg of vitamin C? (2)
𝟔.𝟔𝟎 𝒎𝒈 𝑽𝒊𝒕𝒂𝒎𝒊𝒏 𝑪
𝟐𝟎.𝟎 𝒎𝑳 𝑱𝒖𝒊𝒄𝒆
=
𝟔𝟎 𝒎𝒈 𝑽𝒊𝒕𝒂𝒎𝒊𝒏 𝑪
𝟏𝟖𝟐 𝒎𝑳 𝑱𝒖𝒊𝒄𝒆
2. When evaporation at the ocean surface exceeds precipitation, the salinity of seawater (2)
a. increases
b. decreases
c. stays the same
3. Compared with open ocean water near the equator, the open ocean water in the North Atlantic (2)
a. is colder and less dense
b. warmer and more dense
c. is colder and more dense
d. colder with the same density
4. Give two examples of a homogeneous mixture. (2)
Coca ~ Cola
Tap water
5. Give two examples of a heterogeneous mixture. (2)
Pizza
Beach Sand
6. When the chromatography strip was spotted with a green pen, the dye separated into blue and
yellow dyes. The yellow dye was located near the bottom of the strip while the blue was located near
the top. What three molecular properties account for the difference in location of the dyes in the
marker? (3)
1. Size
2. Mass
3. Solubility
7. In lecture I had one balloon filled with hydrogen gas, and one balloon is filled with oxygen gas. Just by
looking at the balloons, how can you distinguish one gas from the other? (2)
The hydrogen balloon floats in air.
8. Write a balanced chemical reaction for the electrolysis of water. (2)
2 H2O
2 H 2 + O2
9. The temperature of melting ice doesn’t rise as it is heated because (2)
a. energy is going to the breaking of bonds between hydrogen and oxygen rather than to
increasing the temperature of the ice.
b. energy is going to the breaking of bonds between water molecules rather than to increasing
the temperature of the ice.
c. energy is going to the making of bonds between water molecules rather than to increasing the
temperature of the ice.
d. energy is going to the making of bonds between hydrogen and oxygen rather than to
increasing the temperature of the ice.
10. If you prepare a saturated solution of a compound and place a crystal of that substance into the
solution, (2)
a. the crystal will dissolve.
b. the crystal will not dissolve.
c. the crystal will cause the solution to crystallize.
d. the crystal will melt