Question

what are the steps to find the mass of 30 mL of water

Answer 1

what kind of measuring devices do you have available?

Answer 2

I would say:

- weigh an empty box.
- fill 30ml water into said box.
- weigh again.
- the difference in masses equals the mass of water.

Answer 3

What Schleifspur is describing will give you the weight of the water, not the mass. To find the mass you should know the following:

1 g H2O = 1 mL H2O = 1 cm^3 H2O

So using this you know you have a mass of 30g H2O!

Answer 4

use volume and density if its pure water.
Volume*density=mass

if its tap water or some other sample then use Schleifspur method.

Answer 5

Kainui: please explain to me the difference between weight and mass. I mean, where is your formula without someone weighing a cup of water first? =)

Answer 6

The difference between weight and mass is that mass does not change between being on earth or the moon, but weight does, since weight is a force dependent upon the acceleration due to gravity. So although I weigh less on the moon as opposed to the earth, I am made up of the same exact amount of mass on both.
\[F=m*a\]
Weight is a force, measured in Newtons, mass is measured in kilograms (or grams), so weighing does not find the mass.

You are right though in some ways, you can find the mass by using something such as a triple beam balance. I was going by the generally accepted fact of pure water at 4 degrees celsius:
\[1g = 1mL=1cm ^{3}\]

Which will probably be an extremely close estimate to what the mass of the water really is.

Answer 7

did he say he wanted to determine the mass of water ON THE FRICKIN MOON??? =) good answer though, will remember that

Answer 8

The mass of water on the moon is the same as the mass on earth, so it doesn't matter. =P