Converting grams to moles?

Question

I know how to convert grams to moles when using the same substance. However, an assignment in my chemistry packet wants to know how many moles of a substance I must have to produce a certain amount of grams of another substance.

The problem asks: How many moles of nitromethane are needed to form 500.0 grams of chloropicrin, CCl3NO2, a chemical used in the production of pesticides?

CH3NO2 (l) + 3 Cl2 (g) ---> CCl3NO2 (l) + 3 HCl (g).

How would I go about this?

Answer 1

convert grams of chloropicrin to moles

moles of chloropicrin=moles of nitromethane... becuase there is a 1 to 1 mole ratio of the coefficients
1CH3NO2 =1CCl3NO2

Answer 2

Find the mols of Nitromethane and of Chloropicrin

CH3NO2 + 3Cl2 → CCl3NO2 + 3HCl
(12+3+14+32 nitromethane g-mol) →
(12+106+14+32 chloropicrin g-mol)

61 g-mol Nitromethane gave 164 g-mol Chloropicrin.
(Mols may be expressed as any mass unit: - g, kg, lb..etc)
Therefore to produce 500g of Chloropicrin:

(164 ÷ 61) x 500 = 1344g-mol = 1344g Nitromethane.

Answer 3

Balance the equation. When you do that then you will probably have coefficients in front of each individual compound. No coefficient being 1 of course. Those are the molar ratios. You use those to figure it out.

For example.

2(H2) + O2 = 2(H2O)

The ratio between the hydrogen gas and the water is 1-1. Therefore whatever amount of H2 you have in moles produces the same number of moles of water.

The oxygen/water ratio is 1-2. So you need to double the amount of O2 in moles in order to get the amount of water.

This also works in reverse, water/H2 or O2.

So find how many moles are in 500g of chloropicrin and use the ratios to find the amount of product. Then simple convert the amount of product into grams.

Answer 4

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