## Density Lab B

UTF-8 U+6211 U+662F
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### Re: Density Lab B

Anomaly wrote:
UTF-8 U+6211 U+662F wrote:Describe processes to measure out the densities of:
a) a metal cylinder
b) a blob of wax
c) some unknown liquid
d) a rubber band ball
I feel like we measured the densities of like half of these in Chemistry today :/
we did the same thing two weeks ago Jacobi
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### Re: Density Lab B

UTF-8 U+6211 U+662F wrote:Describe processes to measure out the densities of:
a) a metal cylinder
b) a blob of wax
c) some unknown liquid
d) a rubber band ball
`Measure out an accurate amount of water into a measuring device.  Weigh the object.  Then, place the object into the water and measure the change in the water volume, that is, the object's volume.  Divide the mass and volume to get the density. This works for all solid objects, including porous and amorphous ones.`
I was assuming that it is a solid blob of wax, not a blob of molten wax.
`Weigh a graduated cylinder.  Measure out a certain, known volume of the liquid into the cylinder.  Weigh the cylinder again.  Calculate the difference in masses between the cylinder before and after adding the liquid.  This is the mass of the liquid.  Divide this value by the volume added initially.  This is the density.`

UTF-8 U+6211 U+662F
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### Re: Density Lab B

Jacobi wrote:
UTF-8 U+6211 U+662F wrote:Describe processes to measure out the densities of:
a) a metal cylinder
b) a blob of wax
c) some unknown liquid
d) a rubber band ball
`Measure out an accurate amount of water into a measuring device.  Weigh the object.  Then, place the object into the water and measure the change in the water volume, that is, the object's volume.  Divide the mass and volume to get the density. This works for all solid objects, including porous and amorphous ones.`
I was assuming that it is a solid blob of wax, not a blob of molten wax.
`Weigh a graduated cylinder.  Measure out a certain, known volume of the liquid into the cylinder.  Weigh the cylinder again.  Calculate the difference in masses between the cylinder before and after adding the liquid.  This is the mass of the liquid.  Divide this value by the volume added initially.  This is the density.`
`Your answer for B is off. Wax will float in water. You have to use a different liquid.`

MattChina
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### Re: Density Lab B

lets restart this
```1. What is the molarity when 0.75 mol is dissolved in 2.50 L of solution?
2. What is the concentration in ppm of selenium if 1.3 milligrams
is found in 2500 kg of soil?
3. Calculate the concentration of salt in a solution of water in
percent if 45 grams is dissolved in 1200 ml of water.```
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bobthebuilderman
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### Re: Density Lab B

MattChina wrote:lets restart this
```1. What is the molarity when 0.75 mol is dissolved in 2.50 L of solution?
2. What is the concentration in ppm of selenium if 1.3 milligrams
is found in 2500 kg of soil?
3. Calculate the concentration of salt in a solution of water in
percent if 45 grams is dissolved in 1200 ml of water.```
1. 0.3 mol/L
2. 0.0052 ppm
3. 3.75%

Not sure if these are correct.
yes

knightmoves
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### Re: Density Lab B

UTF-8 U+6211 U+662F wrote:
`Your answer for B is off. Wax will float in water. You have to use a different liquid.`
`Impale the wax blob on the end of a pointy stick and submerge. Then submerge the naked pointy stick to the same mark and subtract. Cheaper and probably more easily accessible than a beaker of IPA.`

MattChina
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### Re: Density Lab B

bobthebuilderman wrote:
MattChina wrote:lets restart this
```1. What is the molarity when 0.75 mol is dissolved in 2.50 L of solution?
2. What is the concentration in ppm of selenium if 1.3 milligrams
is found in 2500 kg of soil?
3. Calculate the concentration of salt in a solution of water in
percent if 45 grams is dissolved in 1200 ml of water.```
1. 0.3 mol/L
2. 0.0052 ppm
3. 3.75%

Not sure if these are correct.
Looks good to me. Your turn.
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bobthebuilderman
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### Re: Density Lab B

1. What is the density of each liquid in the jar that:
- has a volume 10 L
- contains equal amounts of Liquid A and Liquid B
- Liquid A weighs 60 grams

2. What is the density of water at 0 degrees C? -50 degrees C? 100 degrees C?
3. What is the population density of country A if it has 545,000 people in 10,000 squared km?
yes

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### Re: Density Lab B

hol up
bobthebuilderman wrote:1. What is the density of each liquid in the jar that:
- has a volume 10 L
- contains equal amounts of Liquid A and Liquid B
- Liquid A weighs 60 grams

2. What is the density of water at 0 degrees C? -50 degrees C? 100 degrees C?
3. What is the population density of country A if it has 545,000 people in 10,000 squared km?
1. Cannot answer without liquid B's mass
2. Ok so water is its most dense at 3.98C, at 1 g/cm^3. So, using water's volumetric temperature expansion coefficient (0.0002 m3/m3 degrees C), water is:
0C - 999.204633112 kg/m^3
-50C - 989.319308743 kg/m^3
-100C - 979.627663118 kg/m^3
3. 545 people per km^2
RIP 2020 szn, shortlived but not forgotten

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UTF-8 U+6211 U+662F
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### Re: Density Lab B

bobthebuilderman wrote:1. What is the density of each liquid in the jar that:
- has a volume 10 L
- contains equal amounts of Liquid A and Liquid B
- Liquid A weighs 60 grams

2. What is the density of water at 0 degrees C? -50 degrees C? 100 degrees C?
3. What is the population density of country A if it has 545,000 people in 10,000 squared km?
1. Cannot answer without liquid B's mass
2. Ok so water is its most dense at 3.98C, at 1 g/cm^3. So, using water's volumetric temperature expansion coefficient (0.0002 m3/m3 degrees C), water is:
0C - 999.204633112 kg/m^3
-50C - 989.319308743 kg/m^3
-100C - 979.627663118 kg/m^3
3. 545 people per km^2