density review mrs. o’rourke september, 2006. question #1 density of different items:...

Density ReviewDensity ReviewDensity ReviewDensity ReviewMrs. O’RourkeMrs. O’Rourke

September, 2006September, 2006

Question #1• Density of different

items:– Gasoline—0.7 g/ml– Water—1.0 g/ml– Aluminum—2.7

g/cm3

– Iron—7.3 g/cm3

– Silver—10.5 g/cm3

– Lead—11.3 g/cm3

– Gold 19.3 g/cm3

• Mercury, a metallic liquid element, has a density of 11.3 g/ml. If you placed the metals listed to the left in mercury, draw and label a graduated cylinder that shows what would happen?

Question #1 Answer• The column should show that all

would float, except gold. The lead could be shown as suspended in the mercury.

Question #2• Which of the following would float on

pure water?– A. A substance with a mass of 1.33 g and a

volume of 1.38 mL.– B. A substance with a volume of 3.35 mL

and a mass of 22. 64 g.– C. A substance with a volume of 436.2 mL

and a mass of 418.23 g.– D. A substance with a mass of 534.23 g

and a volume of 522.3 mL.

Question #2 Answer• Both A and C would float on water.

Question #3• Mass is equal to ????, while

volume is equal to ?????– A. Density/volume; mass/density– B. Density/volume; mass X density– C. Density X volume; mass X density– D. Density X volume; mass/density

Question #3 Answer• D; mass is equal to density X

volume; volume is equal to mass/density.

Question #4• Alicia has a pure gold coin that has

a mass of 120.24g. Gold has a density of 19.3 g/cm3. What is the volume of the coin?

Question #4 Answer• 6.23 cm3

Question #5• When water freezes it expands it’s

volume by 7%. What is the density of ice?– 0.30 g/mL– 1.7 g/mL– 1.07 g/mL– 0.93 g/mL

Question #5 Answer• 0.93 g/mL

Question #6• Density of different

items:– Gasoline—0.7 g/ml– Water—1.0 g/ml– Aluminum—2.7 g/cm3

– Iron—7.3 g/cm3

– Silver—10.5 g/cm3

– Lead—11.3 g/cm3

– Gold 19.3 g/cm3

• Keshia has 3.0 cm3 of gold, lead, silver, iron, and aluminum. Which of the following is false?– A. All of the samples

have different masses– B. The aluminum has

the smallest mass– C. The gold has the

greatest volume– D. The silver has a

mass of 31.5 grams.

Question #6 Answer• C; They all have the same

volume: 3cm3. Gold would have the most mass.

Question #7• Jose has a 10 cm3 sample of silver while

Alicia has a 30 cm3 of silver. Which of the following is false?– A. Alicia’s sample has 3 times the volume

of Jose’s sample.– B. Alicia’s sample has 3 times the density

of Jose’s sample.– C. Alicia’s sample has 3 times the mass of

Jose’s sample.– D. Jose’s sample has 1/3 the mass of

Alicia’s.

Question #7 Answer• B; density of an object does not

change when you ONLY cut it into smaller pieces. You must heat it, cool it, add a solute to the solvent, or increase or decrease the pressure on the substance to change the density.

Question #8• If you heat a sample of gas, the

density of the gas:– A. Remains the same– B. Decreases– C. Increases– D. Impossible to tell

Question #8 Answer• B; when you heat a gas, the

volume expands due to the increase of the speed of the molecules. The mass would stay the same, volume would increase, so density would decrease.

Question #9• An object has these dimensions:

The length is 5 cm, the width is 2 cm, and the height is 10 cm. What is the volume?

• If the object has a mass of 65 grams, what is its density?

Question #9 Answer• 100 cm3; 5 cm X 2 cm X 10 cm• .65 g/cm3; 65g/100cm3

Question #10• Your teacher gives you a little

block of metal which is exactly 1 centimeter square. It is small, but has a mass of 4.5 grams. What is its density?

Question #10 Answer• 4.5 g/cm3; 4.5g/1cm3

Question #11• A piece of metal has a mass of 3

grams and has a density of 2.70 g/cm3. What is its volume?

Question #11 Answer• 1.11 cm3

Question #12• A piece of foil has a volume of

0.90 cubic centimeters. If the foil is 30 centimeters by 18 centimeters, what is its height.

Question #12 Answer• .0016666 cm

– 30 X 18 X .0016666 = .90

Question #13• A piece of aluminum foil has a

mass of 1.60 grams. It is 30 cm by 10 cm. If we assume that the density of the foil is 2.70 g/cm3, what is the thickness of the foil?

Question #13 Answer• .00197 or .002

Question #14• A furniture maker wants to determine if

two pieces of wood are of the same type. He knows that the two woods have different densities. The first piece is 30 X 14 X 2.5 cm and has a mass of 350 grams. The second piece is 15 X15 X 10 cm and has a mass of 900 grams. Are they different types of wood?

Question #14 Answer• yes; the density of the first piece

is .33 g/cm3, the density of the second piece is 1.2 g/cm3.

Question #15• When salt is added to water the density

increases. Marine biologists use this characteristic to measure the salinity in sea water. A biologist knows that the density of the water must be between 1.05 and 1.08 g/cm3. She finds that 80 mL has a mass of 83.2 grams. Is this water within the limits?

Question #15 Answer• No, It is only 1.04 g/mL, so the

salinity level is too low.

Question #16• 28.5g of iron shot is added to a

graduated cylinder containing 45.50 mL of water. The water level rises to the 49.10 mL mark. What is the density of iron?

Question #16 Answer• 7.9166 or 7.92 g/cm3

Question #17• A piece of wood that measures 3 X

6 X 4 cm has a mass of 80 grams. What is the density of the wood?

• Would it float in water?

Question #17 Answer• 1.11 g/cm3

• No, it will not float. It is more dense than water.

Question #18• A cup of gold colored beads was

measured to have a mass of 425 grams. By water displacement the volume of the beads was calculated to be 48.0 cm3. Given the following densities, identify the metal:

• Gold: 19.3 g/cm3

• Copper: 8.86 g/cm3

• Bronze: 9.87 g/cm3

Question #18 Answer• copper

Question #19• Lynn threw a plastic ball into his pool

for his dog to fetch. The mass of the ball was 125 grams. What must the volume be to have a density of 0.50 g/cm3. (He wants it to float, of course!)

• After throwing the ball into the pool, it sprang a leak and began to fill up with water. How many mL of water can the ball absorb before the ball sinks?

Question #19 Answer• The ball must have a volume of

250 cm3.• When the ball has absorbed 126

mL it will sink

Question #20• What is the mass of a cylinder of

lead that is 2.50 cm in diameter and 5.50 cm long? The density is 11.4 g/cm3.

Question #20 Answer• 97.926 or 97.93 g

Question #21• An ice cube measuring 5.80 cm by

5.80 cm has a density of 0.917 g/mL. What is the mass of the ice cube?

Question #21 Answer• 178.9177 or 178.92 g

Question #22• Gasoline is non-polar liquid that

will float on water. 450 grams of gasoline is spilled into a puddle of water. If the density of gasoline is 0.665 g/mL, what volume of gasoline was spilled?

Question #22 Answer• 676.69 mL

Question #23• A little aluminum boat (mass of

14.50g) has a volume of 450.00 cm3. The boat is placed in a small bucket of water and carefully filled with pennies. If each penny has a mass of 2.50g, how many pennies can be added to the boat before it sinks?

Question #23 Answer• 175 pennies• Mass to volume must be greater than 1.

450 mL would need to have just over 450 g to sink. We have 14.5 g. 450 – 14.5 = 435.5g

• 435.5/2.5 (gram per penny) = 174.2. So you must add 175 pennies to sink your boat.

Question #24• A sample of the mineral pyrite has

a mass of 150g and a volume of 30 cm3. What is the density of pyrite?

• If I cut my sample of pyrite in half; what would its new mass, volume, and density be?

Question #24 Answer• The density of pyrite would be 5

g/cm3.• If the sample were cut in half, the

mass and volume would as be cut in half; however, the density would not change. New mass: 75g. New volume: 15 cm3.