1) What is a physical property?
A physical property is a property that can be observed and measured without changing the chemical makeup of the substance.
2) Identify three physical properties of water.
-Boiling point: 100°C or 212°F.
-Freezing point: 0°C or 32°F.
-Density: 1g/mL or 1g/cm^3
3) How does the density of solid water compare to the density of liquid water?
Since ice floats on the suface of liquid water, it is less dense.
4) Describe a setting where you might observe water as a solid, a liquid, and gas all at the same time.
One might observe water as a solid, a liquid, and a gas all at the same time in winter, at a waterfall in the mountains. The mountains surrounding the waterfall would be frozen, and as the powerful waterfall would crash onto the body of water below, many particles of water would rise into the air as water vapor, or gas. The cold mountains tend to be foggy as well, and fog is defined as a thick cloud of water droplets suspended in the atmosphere.
5) How are heterogeneous and homogeneous mixtures different?
In a heterogeneous mixture, the composition of it is not evenly distributed, or uniform, throughout. On the other hand, a homogeneous mixture is a mixture that is uniform throughout.
6) When gasoline and water are poured into the same container, they form two distinct layers. What do you need to know to predict which liquid will be on top?
In order to predict which liquid will be on top, it is necessary to know the densities of gasoline and water. The substance with the lower density would be on top.
7) Identify each of the following materials as a solution, a suspension, or a colloid.
a. A medicine accompanied by instructions to "shake before using"
b. Italian salad dressing
c. Mayonnaise.
d. A cola soft drink.
e. An oil-based paint.
f. Milk
a. A suspension
b. A suspension
c. A colloid
d. A solution
e. A suspension
f. A colloid
8) You notice beams of light passing into a darkened room through the blinds on a window. Does this demonstrate that air in the room is a solution, a suspension, or a collid? Explain.
Just like the Tyndall Effect, the beam of light passing into a darkened room through the blinds on a window reflects that since the light shines all the way through the room, it shows that there are small particles present in the air. This means that the air in the room is a collid; these particles are too small to come out through a filter. Although air appears to be a homogeneous mixture, the Tyndall Effect done through natural light proves that it is a heterogeneous mixture.
9) Drawing: separate paper.
10) Suppose you have a clear, red liquid mixture. A beam of light is observed as it passes through the mixture. Over a period of time, no particles settle to the bottom of the container. Classify this mixture as a solution, a collid, or a suspension, and provide evidence to justify your choice.
This mixture is a collid. Since with the Tyndall Effect, the beam of light passes through the mixture, it is evident that the particles within the mixture are small, but not actually part of the mixture. Therefore, this mixture can not be a solution. Furthermore, since over a period of time, no particles settle to the bottom of the container, the mixture is not a suspension.
11) Define the term substance and give two examples.
A substance is an element or compound with a uniform and definite composition, as well as distinct properties. The smallest substance is a molecule, which is composed of atoms that are held together by chemical bonds. Two examples of substances are water, H2O, and ammonia, NH3.
12) Classify each of the following substances as an element or a compound.
a. CO
b. Co
c. HCl
d. Mg
e. NaHCO3
f. NO
g. I2
a. Compound
b. Element
c. Compound
d. Element
e. Compound
f. Compound
g. Compound
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