how do I set up an equation that asks how many grams of Cl2 are needed ot react with 2.00 grams of Na

Write down a chemical equation with sodium (Na) and chlorine (Cl2) on the left side. Draw an arrow to the right, and on the right of the arrow, write the products that you expect from the reaction.

If you don't know what the products are, you can always Google "Na + Cl2".

That's the start. The equation shows you how many moles of chlorine react moles of sodium. You calculate the atomic or molecular weight of each species (atomic weight if there's only one atom of an element; molecular weight if there is more than one atom in the group).

Atomic and molecular weights are in grams/mole. If you divide grams by grams/mole, you'll get moles. If you multiply moles by grams/mole, you'll get grams.

Once you figure out how many moles of Na 2.00 grams is, you can figure out how many moles of Cl2 are required to react with it. You then multiply (see preceding paragraph) that with the molecular weight of chlorine.

Think about it. It's quite easy.

Follow up on Perito's post : let's go one step further.

Follow this link to see the data on Sodium (Na) (http://en.wikipedia.org/wiki/Sodium)

Follow this link to see the data on Chlorine (Cl)
(http://en.wikipedia.org/wiki/Chlorine)
See also this link to data on the Na Cl reaction (http://chemed.chem.purdue.edu/demos/main_pages/7.1.html) : (Na + 1/2 Cl2 --> NaCl , so 2 Na + Cl2 = 2 NaCl)

Note that in the first 2 links in the righthand column the atomic weight is provided, so you can calculate how many atoms are involved in 2.00 grams Sodium, and from the provided reaction how many atoms of Chlorine are needed.

Success!