Density Value to solve problem?

Question

I am really bad at conversions after being out of
school for a very long time. Can someone show
me step by step the best way to deal with conversions
in general. This is a little different than the previous
question I had.


What is the mass, in grams, of 120 mL od liquid
with a density of 1.8 g/mL?

Answer 1

120x1.8=216g
u have g/ml multiplied with ml so u get grams because like it's like in fractions. for example 3/2 multiplied with 2 equals 3.

Answer 2

The best way I know to stay sane doing conversions is to treat the unit of measure as a variable to be cancelled out.

To use your example, you have 120 mL and a density of 1.8 g/mL. If you multiply the "mL" (forget the number for now) times the "g/mL" the product will be "g", which is what you're looking for. The "mL's" cancel out (one is the numerator and one is the denominator) in the multiplication.

So thus you either multiply or divide to get the unit of measure that you want as a result.

Hope this helps!
Stan F.

Answer 3

The formula is : m=V*d,
where m is the mass of a homogeneous body, V is its volume and d is the density of the material of which the body is made of.
In this problem: V=120 ml, d= 1.8g/ml, m= in grams? The units are all consistant.
So : m = 120*1.8 =216 g
Halliday and Resnick (Physics Book) handles the conversions of units quite well.

Answer 4

Simple rule of conversions is that;

All units other than the one required (in this case grams) should be cancelled.

This is only possible if the unit (in this case mL) is divided by another same unit (mL in the denominator)

Remember that units are treated just like any mathematical calculation.

So you will achieve your result in this case by multiplying g/mL (density) by mL (volume) thus the mL in the denominator (of density) will cancel with the mL in the numerator (volume) and only grams will remain in the end.

Answer 5

D = m/v

1.8 = m/120
m = 1.8 x 120

Answer 6

d=m/v

1.8=m/120
m=1.8/120

m=0.015g