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

Viernes 19 de febrero del 2010

Miercoles 17 de febrero del 2010

oday was our first real class, and we saw a new subject: STOICHIOMETRY. Technically speaking, stoichiometry is the part of chemistry that deals with amounts and quantities, and we can use it to calculate masses, moles, and percents within a quemical equiation (In short words, stoichiometry is the math behind chemistry).

We also saw the Chemical Yield (or Reaction Yield) is the ammount of product obtained in a chemical reaction; in a chemical reaction it would be like this:

2H2 + O2 (Reactants) ------> 2H2O (Products)


The reason of the recipes (short and easy) was to explain with easier words the stoichiometry; the example we used was the Chocolate Milkshake recipe, and in that part i learned that the quantity of ingredients depended on the amount that was going to be used for all (at least that's what i understood).

Homar Hurtado