[ericbmd]

I am taking an internet chemistry class and am having some problems with Density.  It seems simple in the notes but when I go to work a problem I am struggling a little.
A glass vessel calibrated to contain 19.84mL of Water at 4 degrees C was found to weigh 31.962g when empty and dry.  Filled with a sodium chloride solution at the same temperature, it is found to weigh 54.831g.  Calculate the soultions density??  Is this correct. 
Density = mass(g)/Volume(ml)
D=19.84ml/54.831g  = .3618g/ml


A sample of urine weighed 25.853g at 4 degrees C.  An equal volume of water at the same temp weighed 23.718g.  At 4 degrees C, the density of water is exactly 1.000g/cm3.  Calculate the density of the urine sample. 

In our text book it says that the density of urine is 1.003-1.030 at 25degrees C is that the answer?  I don't think it is..
how does the temperature play a part in the equation?


I know that I am making this harder that it really is.  thanks for any pointers or help you can give me

[mike]

I am taking an internet chemistry class and am having some problems with Density.  It seems simple in the notes but when I go to work a problem I am struggling a little.
A glass vessel calibrated to contain 19.84mL of Water at 4 degrees C was found to weigh 31.962g when empty and dry.  Filled with a sodium chloride solution at the same temperature, it is found to weigh 54.831g.  Calculate the soultions density??  Is this correct.
Density = mass(g)/Volume(ml)
D=19.84ml/54.831g  = .3618g/ml

First, you need to subtract the mass of the empty glass vessel from the total mass of 54.831g, this will give you the mass of the solution.

Second, when you calculated D, you have mixed up the mass and the volume, density = mass/volume so should be g/mL (check your working out)

[ericbmd]

thanks for the help with setting up the first problem. Any pointers on the second problem listed below