hw question E23?

[connie 2C]

How do you calculate the moles of an ion in a molecular compound? What conversion factor would be used?

[romina_4C]

To calculate the moles of an ion in a molecular compound, you see how many moles of that are present in the compound and use that number as the multiplication factor. For example, to see how many moles of Na+ are in Na2CO3, you would find the total number of moles of Na2CO3, and you know that for each mole of Na2CO3, there are 2 moles of Na+ (in the compound itself Na has a subscript of 2), and thus you can calculate the moles of that ion using the subscript of the ion in the compound as a multiplication factor.

[Michelle Le 1J]

For CuBr2, since you know that it consists of only one Cu2+ ion by looking at its formula, you would use the conversion factor (1 mol Cu2+/1 mol CuBr2) and multiply that to the mols of CuBr2 to find the moles of ions. If the question were asking about the amount of ions and not its moles, you would then have to use Avogadro's number to calculate that.

[Aprice_1J]

The first thing that you want to do is convert the given amount to moles. When you have it in moles you can use the stoichiometric coefficients to set up ratios. For the ratios the best way to think of it is setting it up so that everything cancels. If you find the moles of CuBr and you want to get to Cu, make sure that the units in the ratio cancel out so you are just left with Cu. From there you can continue using the ratios to find what you are looking for. Something that really helped me put everything in the correct place was to write out everything with the units and physically cross out what cancels.