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Mass density

The mass density of an object is the ratio of its mass m to its volume V (mass density is denoted by ρ).

So the formula for mass density is: ρ = m / V

The unit of ρ depends on those of m and V:

If m is in kilograms (kg) and V is in liters (L) then ρ is in kg/L
If m is in grams (g) and V is in milliliters (mL) then ρ is in g/mL
If m is in kilograms (kg) and V is in cubic meters (m³) then ρ is in kg/m³, etc...

Example: 0.5L (or 500mL) of water has a mass of 500g, so ρ_water = m/V = 500/0.5 = 1000g/L (or 1kg/L)

Important property: The value of mass density is characteristic of a pure substance.

For example, if the mass density is 1kg/L, I am sure it's water because this mass density value is characteristic of water.

I suggest you use this property to find the mass density of an unknown liquid (Time to work! 😁).

In the laboratory, we poured a colorless liquid into a container but forgot to label it, it could be one of the following liquids:

water

dichloromethane

butan-1-ol

cyclohexane

hexane

ρ_water=1000g/L

ρ_{dichloromethane}=1330g/L

ρ_butan-1-ol=810g/L

ρ_cyclohexane=779g/L

ρ_hexane=660g/L

Method (protocol) to Identify the unknown liquid (randomly generated):

Make a list of the equipment to use.
Measure the volume.
Find the mass.
Deduce the mass density, then identify the unknown liquid.

1. Choosing your equipment

You'll need to measure the volume of the unknown liquid and then weigh it, so choose the appropriate equipment.

Choose the volume of unknown solution to be taken (it's a choice, all answers are correct and the proposed values are random):

Click on the equipment you need (click again to deselect):

25 mL graduated cylinder

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100 mL graduated cylinder

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250 mL graduated cylinder

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250mL beaker

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100 mL volumetric flask

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electronic balance

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pipette dropper

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unknown liquid

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click and hold to adjust volume

normal speed

drop by drop

Equipment used:

250 mL graduated cylinder
electronic balance
Note: when you press the TARE button, the balance displays 0g

Click on "I've obtained the mass of the liquid" when the balance shows the correct mass

4. Identify the unknown liquid !

SuperCalculator 😁

÷ =

🔼 drag / drop 🔼