How do you calculate moles to grams?

Answer 1

Use the equation.

moles = mass(g) / Mr

The 'Mr' is the Relative Molecular Mass of any substance. You take the Atomic masses from the Periodic Table.

So taking water as an example

The formula for water is H2O

From this formula we know that there are two(2) hydrogen(H) atoms and one(1) oxygen atom(O).

From the Periodic Table the Atomic Mass of 'H' is '1' and the atomic mass of 'O' is '16'.

So using the formula and the masses

we have

2 x H = 2 x 1 = 2

1 x O = 1 x 16 = 16

We then add these two numbers. 2 + 16 = 18 .

'18' is the 'Mr' of water (H2O).

So calculating the number of moles of water in say 72 grams.

Substitute in

moles(H2) = 72 g / 18

moles(water). = 4

NB Since pure water at STP(Room temperature and air pressure) the scientific standard is 1 gram = 1 cm^(3)

So if you have a measuring cylinder, and put into it 72 cm^(3) of water , you have 72 grames of water, and by the above calculation , you also have 4 moles of water.

NNB moles = mass(g) / Mr

This is a mathemtical equation and can be algebraically rearranged to

Mass(g) = moles X Mr

or

Mr = mass(g) / moles.

Hope that helps!!!!!

Answer 2

The measurement in grams depends on the molecule you are using in your conversion. You must find the molecules total atomic mass before you begin the conversion.

Example:

How many grams are in one mole of NE?

Solve:

1. NE's atomic mass is 20.180

2. We must set this up so that the moles cancel out:

1 mole NE/1 = 20.180g/1 mole NE

3. Once you cancel out the moles and solve, you are left with 20.180g.

4. ALWAYS take into acount your significant figures!!! This will make the answer 20g.

Overview:

As long as you are converting 1 mole into grams, the answer will just be the atomic mass of the molecule. That's a good shortcut, but remember, it MUST be just 1 mole.

Answer 3

Chemical Engineers sometimes measure substance amount in units of gram-moles, kilogram-moles, pound-moles, or ounce-moles; these measure the quantity of a substance whose molecular weight is not equal to its mass in grams, kilograms, pounds, or ounces. The SI mole is identical to the gram-mole. This is from wikipedia entry on moles. So 1 mole = 1 gram-mole

Answer 4

Multiply molar mass (gram per mole) of a compound with the number of moles of that compound to find the mass (in grams)

Answer 5

moles of X mulitplied by g/mol or the molecular weight of the element/compound X equals grams.

Answer 6

To convert moles to grams, you can use the molar mass of the substance. Simply multiply the number of moles by the molar mass to get the mass in grams. The formula is: mass (g) = moles x molar mass.