Perform each of the following conversions show all set-ups: a) 44.00 mol Ca=? g Ca, b) 38.50 g NH3 =?mol NH3?

Question

I just don't how to solve them i'm lost please help

Answer 1

For the first one, we must convert moles of Calcium to grams of Calcium. Looking at the periodic chart tells us that there is 40.078 grams of Calcium in one mole. Therefore:

44.00 mol Ca X (40.078g Ca / 1 mol Ca) = 1763.432 grams Ca

The correct answer to FOUR significant figures is 1763 g Ca.

The second is just the opposite: we must go from grams ammonia to moles of ammonia. There are 17.03052 grams in one mole of ammonia (from the periodic chart). Therefore:

38.50 g NH3 X (1 mol NH3 / 17.03052 g NH3) = 1.96705679 mol NH3

The correct answer to FOUR significant figures is 1.967 mol NH3.

I hope this helps!