We also know that the coefficient of NaCl is 2 and the coefficient of Cl 2 is 1. We know that we have 0.03300144 mole of Cl 2. In case you can't see this, it is moles of Cl 2 x (coefficient of NaCl / coefficient of Cl2). We use these coefficients in the equation to convert from Cl 2 to NaCl. (Remember that if a compound or element doesn't have a coefficient, the coefficient automatically equals 1.) The coefficient for NaCl in the balanced chemical equation is 2. The coefficient for Cl 2 in the balanced chemical equation is 1. The coefficient for Na in the balanced chemical equation is 2. The big numbers in front of the compounds are called coefficients. We look at the balanced chemical equation that the problem gave us: 2 Na + Cl 2 -> 2 NaCl. First we need to convert our 0.03300144 mole of Cl 2 to moles of NaCl. But the problem wants grams of sodium chloride (NaCl). So in other words, we know that there is 0.03300144 mole of Cl 2 in 2.34 grams of Cl 2. Since the 'grams of Cl 2' canceled out, the unit is now 'mole of Cl 2'. So to convert, all we have to do is multiply. This allows the 'grams of Cl 2' to cancel out, so we will be left with 'mole of Cl 2'. Notice that we have 'grams of Cl 2' on the top and the bottom parts. So if we put the numbers in, the equation looks like this: We put 70.906 on the bottom (diagonal from the grams the problem gave us). Remember that the problem gave us 2.34 grams of Cl 2. Grams of Cl 2 the problem gave us x 1 mole of Cl 2 Now we need to convert 2.34 grams of Cl 2 into moles of Cl 2. This means that there are 70.906 grams of Cl 2 in 1 mole of Cl 2. So we are going to have to do 2 x 35.453 because there are 2 Cl in Cl 2. (Remember that the subscript is the small number that comes after the element symbol.) So there are 2 Cl in Cl 2. But if we look at Cl 2, the Cl has a subscript, and the subscript is 2. (Remember that the atomic mass is the number with the decimals.) Ok, so we know that the atomic mass of 1 Cl = 35.453.

The entry for Cl says that the atomic mass of 1 Cl is 35.453. To do this, we look on the periodic table for the atomic mass of Cl. First we need to convert the 2.34 grams of Cl 2 (chlorine gas) to moles of Cl 2.

Periodic table molar mass cl2