So, in this example question, it says, how many grams of chlorine gas are there in 2.34 moles? Alright. So, the 2.34 moles represents our given amount, and we have to determine what our end amount will be. What are we trying to get to? So, our end amount that we need to find is grams. Okay. So here we need to determine the grams of chlorine gas. Now, to go from the given amount to the end amount, we know we have to utilize a conversion factor. So the conversion factor we have up above is the one that we're going to use.
Let's write down our given amount of 2.34 moles of CL2. We need to cancel moles of CL2 so it goes on the bottom. So, just like I said earlier, you can invert your conversion factor. You do that to make sure that units cancel out. To cancel out these moles in red, I need to put these moles in blue on the bottom, and then that one mole of CL2 is equal to 70.90 grams of CL2. So now, moles of CL2 cancel out and we'll be left with grams of CL2 at the end. So when you punch that into your calculator, you should get 165.906, and out of the choices presented, b would be the best choice.
So just remember, our moles we've seen act as a bridge to connect us to particles earlier, and now we're seeing it connecting us to the mass of chlorine gas.