Calculating Density of Unknown Liquid: Problem and Solution

[DoubleHelix]

Hi, here's my problem:

The balance of a bottle when empty is 70.0g, when full of water is 90.0g and when full of another liquid is 94.0g. The density of water is 1000km/m(to the power of 3), what is the density of the toher liquid?

I know that density = mass / volume so i think that i should take 70.0 away from 90.0 to get the mass of the water alone, so I get 20.0g. From here I'm stuck. Thanks for any help!

 

[QuantumCrash]

You know that from the formula of density=mass/ volume.
You have mass of water and density of water. You can calculate the volume of the bottle that way. I'm sure you can take it from there.

 

[DoubleHelix]

Ah yes, so I need to calculate the volume of the bottle.

I found the volume of the bottle to be 0.02 and thus got the density to be = 24.0 / 0.02 = 1200kg m^3. Could you please clarify that i have done this correctly?

 

[td04]

should density be shown in kg/l or g/ml

 

[QuantumCrash]

That answer is accurate. Very good. However I have to point out an error you have made. You did not convert your mass into kg, hence your volume is actually wrong since your density is in kg/m^3 while your mass cancels out. Make sure all your units are continous.

Addtionally, try to have a bearing of the quantities you calculate. 0.02 m^3 is very large, 20 litres, compared to the meagre 90 g of water.

Finally, density in kg/l is valid, however I strongly recommend you use kg/m^3 since that will make both of them SI units. For future questions, converting the units into SI can help you avoid many mistakes.