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klang31
Jun 29, 2009, 06:50 AM
How many grams of C are in 4.20x10 to the power of 23 molecules of (C3H5)2S?

I am not sure what the formula is that I am supposed to use to figure this out.

Perito
Jun 29, 2009, 07:15 AM
Avogadro's number = 6.0221415 \times 10^{23}

One mole of any material contains Avogadro's number of molecules.

Let's show you with an example. The atomic weight of oxygen is approximately 16. The molecular formula for oxygen is O_2. Since there are two atoms of oxygen in a molecule, the molecular weight of O_2 is 32. Therefore, in 32 grams of oxygen, there are 6.0221415 \times 10^{23} molecules of oxygen.

You have 4.20 \times 10^{23} molecules of (C_3H_5)_2S.

1. Calculate the number of moles of that substance.

2. Calculate the molecular weight of that substance

3. Multiply moles by molecular weight (grams per mole)

Grams = moles \,\times\, \frac {grams}{mole}