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Final Exam Review 5
Define the following:
1. Malleability – ability of a substance to be pounded into sheets
2. Density – how tightly packed the atoms of a substance are; ratio of mass to
volume (d = m/v)
3. Tensile Strength – how much pulling a substance can take before tearing
4. Hardness – resistance to scratching
5. Brittleness – tendency of a substance to shatter
6. Buoyancy – upward force on objects in a fluid; equal to the weight of the fluid
displaced
7. Elasticity – how much stretching a substance can take and return to its original
shape
8. Viscosity – resistance to flow
9. Archimede’s Principle – if an object displaces its own weight in fluid, then it will
float
10. Fluids – substances that can flow; liquids and gases
Density
1. What can change density?
Temperature or pressure changes (state change)
2. Draw a picture of a very dense object compared with a less dense object.
3. What is the formula for calculating density?
D = m/v
4. A solid rubber stopper has a mass of 33.0g and a volume of 30.0 cm 3. What is
the density of the rubber?
D = 33.0g/30.0cm3 = 1.10 g/cm3
5. A solid has a mass of 5.019g and is placed into a graduated cylinder with an
initial volume of 49.8mL. The volume of the water rises to 71.3mL. What is the
density of the solid? Volume = 71.3mL – 49.8mL = 21.5 mL
D = 5.019g/21.5mL = 0.233g/mL
6. What is the name of the technique used to find the volume of the object in the
question above?
Water displacement
7. The density of platinum is 21.40 g/cm3. A disk of pure platinum has a volume
of 1130cm3. What is the mass of the disk?
DV = m 1130 cm3 x 21.40 g/cm3 = 24200g
8. The density of sea water is 1.025 g/mL. What is the volume of sea water if the
mass is 975.6g? v = m/d 975.6g/1.025 g/mL = 951.8mL
Final Exam Review 5
Buoyancy
1. When poured into water, glycerol falls to the bottom of the beaker. Which of
the following statements is true?
a. The water is more dense than the glycerol
b. An object that floats in water will always float in glycerol
c. An object that floats in glycerol will always float in water
d. The glycerol is less dense than the water
2. A 4.5 newton object is placed in a tank of water. If the water exerts a force of
4.3 newtons on the object, will it sink or float?
Sink (Force up = 4.3N; Force down = 4.5N)
3. If a boat weighs 200.0 newtons and it displaces 450.0 newtons of water, how
heavy a cargo can it carry?
250.0N
It can displace 450.0; if it displaces its own weight it floats; 450.0 N – 200.0N = 250.0N
A 30.0 cm3 block of paraffin was weighs 0.085N. It is carefully submerged in a
container of gasoline. One cm3 of gasoline weighs 0.0069N. Using this information
answer the following questions.
4. How much gasoline does the block displaced?
30.0 cm3 (its own volume)
5. What is the weight of the displaced gasoline?
30.0 cm3 x 0.0069N/cm3 = 0.21N
6. What is the buoyant force acting on the block?
0.21 N (Buoyant force equals the weight of the displaced fluid)
7. Will the block sink or float?
Float (Force up = 0.21N; Force downward = 0.085N)
When we put ice in water it floats and when we put ice in alcohol it sinks. Use this
information to answer the questions.
8. Rank the materials by their densities from greatest to least.
Water – ice – alcohol
(ice floats in water so water more dense than ice, ice sinks in alcohol so ice is more dense than alcohol)
9. Which liquid had the greater buoyant force, water or alcohol?
Water (it has more tightly packed molecules to support objects)
Gas Laws
10. A tire holds 25.0L of air at 298K. If the temperature drops to 273K, what will be
the new volume of the tire?
Less; because the temperature drops
11. You pump 25.0L of air at atmospheric pressure (101.3kPa) into a soccer ball
that has a volume of 4.5L. What is the pressure inside of the soccer ball?
More; because the pressure decreases