Miercoles 24 de febrero del 2010

Topic: Converting Moles and Grams

Today we had this VERY short topic. We learned to convert moles to grams and grams to moles. It's very easy, first we need a question: How many moles of water will you get if you react 1kg of H with excess O?

As we know, the chemical equation of water is this : 2H2 + O2 → 2H2O

We have 1kg of H but we need to convert it to grams that is equal to 1000 g.

Before resolving a rule of three, we convert the 1000g to moles:

1H2 --- 2g

x --- 1000g

(if 1 mole of H weights 2g, how mant moles weight 1000g?)

1 x 1000 = 1000 / 2 = 500 moles of H weight 1000 g

Now we resolve the rule of three:

2H2 --- 2H2O

500 moles --- x

500 x 2 = 1000 / 2 = 500 moles of H2O

And that's how you convert grams to moles.

Michelle Torrero