# Chemist's Guide to Stoich Part 2

## Step 2: MOLAR MASS/ MOLE TO MOLE CONVERSIONS/MASS TO MASS CONVERSIONS/LIMITING AND EXCESS REACTANT

WELCOME BACK CHILDREN! Lets start off where we left off, we found the IUPAC names of the reactants and products. Now we have to calculate the molar masses of all of the compounds and products. All you have to do is put your mind to this... never mind... but seriously all you have to do is add the atomic masses of all the elements in the compound to get it. Coefficients are not used but subscripts are. What you get after all these calcumulations (A.A) is shown below

Ca(CO3) =100.1072 g HNO3= 63.0132g Ca(NO3)2= 164,9904g CO2= 43.9998g H2O= 18.0154g

NEXT IS MOLE TO MOLE CONVERSIONS

You have to see how many moles of one product are needed to react with a certain number of moles of one reactant.

For example you use a conversion table and multiply across the top and divide by the bottom. The format is in the conversion chart you will make in class. The number of moles for the reactant will be given in the question.

Mine looked like this...

11.3 mol Ca(CO3) x 1 mol Ca(NO3)2 / 1 mol Ca(CO3) =11.3 mol Ca(NO3)2

NEXT IS MASS TO MASS CONVERSIONS

Basically all you have to do is see how many grams of one thing can be produced from another. The format is like the mol to mol conversion except longer. You will learn this in your chemistry class. Mine came out to be 3.54g of Ca(NO3)2

THE END... SIKE YOU THOUGHT WE HAVE ONE MORE SEGMENT IN THIS STEP

FINDING THE LIMITING AND EXCESS REACTANT

you have to make another conversion chart but luckily its just another mass to mass conversion. BUT WAIT THERE IS MORE! YOU HAVE TO MAKE TWO CHARTS FOR TWO REACTANTS. After all of that fun you compare your answers and the least is the limiting and the greatest is the excess.

THE END... for real this time...until...this season...you