Complete the following tables.<br />
Mass (kg) Volume (m³) Density (kg/m³)<br />
350 175 -<br />
- 190 4<br /><br />
Density of Metal (kg/m³) Density of water (kg/m³) Relative Density<br />
- 103 5<br />
8.5 x 103 103 -<br /><br />
Weight (N) Area(m²) Pressure (Nm⁻²)<br />
- 0.04 20,000<br />
1500 500 -
Answers
The density of iridium (Ir) is . What is the volume of a piece of iridium which has a mass of 100 g?
solution:
D = 22.65 g/mL
v = ?
m = 100 g
Rearrange the equation so that volume is on one side of the equal sign and everything else is on the other side of the equal sign.
(Now we know about sig fig, so the answer should only have one sig fig since the number "100" only has one sig fig)
So the answer should be 4mL
b) The density of gold is . What is the mass of a chunk of gold with a volume of 2000 mL?
solution:
v = 2000 mL
m = ?
Rearrange the original equation so that mass is on one side and density and volume are on the other side.
Dv = m
However, the number "2000" only has 1 sig fig so the answer can only have one sig fig the answer is 40,000mL.
c) A chunk of lead has a mass of 500 grams and a volume of 44.1 cubic centimeters. What is the density of lead?
solution:
D = ?
m = 500 g
v = 44.1 cm3
We do not have to rearrange the equation for this problem.
based on 1 sig fig in the number "500".
2 a) The density of hydrogen is . What is the volume of a
hydrogen which has a mass of 10 grams?
solution:
v = ?
m = 10 grams
rearrange the equation so that volume is on one side and everything else is
on the other side.
sig figs tell us that we should only have 1 sig fig
v = 10 L
b) The density of silver is . What is the mass of a silver ingot which
has a volume of 2.5 cubic centimeters.
solution:
v = 2.5 cm3
m = ?
rearrange and put mass on a side by itself.
What about the units of mL and cm3 (they are equal)
Dv = m
mass = 26 grams based on the 2 sig figs in the number "2.5"
c) Your significant other recently gave you a piece of platinum which has a volume of 200. mL. The mass of the platinum is 4290 grams. What is the density of the platinum?
solution:
D = ?
m = 4290 g
v = 200. mL
3. I have heard that if you took all of the gold which had ever been mined in the history of the world, it would fit in a cube which is 10 meters on a side. If the density of gold is , what would be the mass of this cube of gold?
m = ?
v = (10 meters)3 the volume of a cube is length X width X height and since all of the dimensions are 10 meters, then the volume will be (10 m)(10 m)(10 m) = (10 m)3
We need to do some unit conversions. The volume unit in density is mL and the volume unit for the gold sample is cubic meters. We need to get these into the same unit. Remember that 1 mL = 1 cm3
(That is lots of little bitty cubic centimeters isn’t it?)
1 X 109 cm3 = 1 X 109 mL
Dv = m
Now, only one sig fig (because of the 10 meters on a side of the cube)
so the mass is 2 X 1010 grams
(in case you are curious and don’t want to do the conversions, that is 44 million pounds which is 22 thousand tons of gold)
4. 50.0 mL of each of the following liquids are placed into a graduated cylinder:
water density =
mercury density =
benzene density =
carbon tetrachloride density =
a) What mass of each chemical was placed in the graduated cylinder?
solution:
we are given the density of each of the chemicals and the volume of each of the chemicals. The mass can be determined by:
Dv = m
water: (3 sig fig)
mercury: (3 sig fig)
benzene: (2 sig fig)
carbon tetrachloride: (3 sig fig)