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A 50.0 mL graduated cylinder has a mass of 42.3 g. When it is filled with an unknown liquid to the 46.3 mL mark, the cylinder and liquid combined have a mass of 115.1 g. Calculate the density of the liquid in g/cm3. SIG. FIG.

2006-09-12 05:17:53 · 5 answers · asked by dudekunle 3 in Science & Mathematics Chemistry

5 answers

First subtract the cylinder mass from the total mass to get just liquid. So 115.1 - 42.3 = 72.8 g. Since that mass takes up 46.3 mL its density is mass in g divided by volume in cm3.
So 72.8/46.3 = 1.57 g/cm3 that you can call 1.6 g/cm3 because all the numbers just have one sig fig.

2006-09-12 05:24:18 · answer #1 · answered by Rich Z 7 · 0 0

Easy!

Mass of grad cyl + liquid = 115.1 g
Mass of grad cyl = 42.3 g, so subtracting you get the mass of the liquid = 115.1 - 42.3 = 72.8 grams

The volume of the liquid is 46.3 mL

Density = mass/volume, so for this liquid you have:
Density = 72.8 grams/46.3 mL = 1.572 g/mL

Now comes the significant figures part. If you consider the number of significant digits in your experimental values, the best you have is three digits, so you cannot reliably report any more than three digits in your answer. Thus the density would be reported as 1.57 g/mL.

-----------------
The following error analysis will demonstrate why you can't report more than two decimal places (though you could certainly *calculate* more -- 72.8/46.3 = 1.57235421166 . . .):

Assume the precision of your graduated cylinder is ±0.1 mL; thus when you measure 46.3 mL, the true answer could be anywhere between 46.2 - 46.4 mL.

Likewise, assume your precision on the balance is 0.1 g. So, the mass of the cylinder could really be anywhere between 42.2 and 42.4 g, and the combined mass between 115.0 and 115.2 g.

So, the true mass of liquid could range anywhere from a maximum of 115.2 - 42.2 = 73.0 g to a minimum of 115.0 - 42.4 = 72.6 g, for an error range of ±0.2 grams!

Now, let's examine the high end density you could get from these conditions -- maximum mass and minimum volume:
density = g/mL = 73.0g/46.2 mL = 1.580 g/mL

On the low end, you would find:
density = 72.6g/46.4mL = 1.565 g/mL

So, the error analysis indicates that you have a density range of 1.565 - 1.580 g/mL

So, based on an error analysis, you would have to report the density as 1.57 ± 0.1 g/mL, and cannot be any more precise than that.

2006-09-12 05:42:09 · answer #2 · answered by Dave_Stark 7 · 0 0

Density= mass g/ volume ml
115.1 - 42.3 = g the mass of the unkown
since the vol. is 46.3 g, the density of = g of the mass/46.3
= g/ml , taking in considaration that the denisty calculated was the density of the unkown at the temp. when u did uer experiment
Note : you have to do your homework , good luck

2006-09-12 06:20:50 · answer #3 · answered by basimsaleh 4 · 0 0

review some formulas and conversions:
density = mass / volume
1 ml = 1 cm^3

Given in the problem:
mass of cylinder = 42.3 g
mass of cylinder + liquid = 115.1 g
volume of liquid = 46.3 ml = 46.3 cm^3

Required: density of liquid (g/cm^3)

Solution:
density of liquid = mass of liquid / volume of liquid

*we are given already the volume of the liquid, to get the mass:
mass of liquid = (mass of cylinder + liquid) - mass of cylinder
mass of liquid = 115.1 g - 42.3 g
mass of liquid = 72.8 g

density of liquid = 72.8 g / 46.3 cm^3
density of liquid = 1.57 g/cm^3

2006-09-12 05:28:52 · answer #4 · answered by augel 2 · 0 0

density=mass/vol
combined mass of
cyl.and liquid=115.1 gm
mass of cyl=42.3gm
mass of liquid=115.1-42.3
=72.8gm
vol of liquid=46.3ml=46.3cc
density=72.8/46.3
=1.57

2006-09-12 05:27:28 · answer #5 · answered by openpsychy 6 · 0 0

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