We have to start with "". If we want to balance <u>Cr</u> we have to obtain <u>2 on both sides</u>. Therefore we have to add a "2" on the right side, so:
Then we can balance "" as a whole. We have <u>6 on the right</u>, we have to have the same amount on the left side, so:
Then we can balance "". We have 6 on the left, so we have to have the same amount on the right if we already have 2 we have to put a · in front (on the right side) to obtain in <u>total 6</u>, so:
Finally, when we add this last number the we will have 3 on both sides. Therefore the reaction is <u>already balanced</u>.
So multiply number of moles x number of atoms/mole = 1.8066 x 10^24 atoms of H2. One mole of any gas at STP has a volume of 22.4 L. So first determine the number of moles of gas you have. for example do 7