1) How many moles are in 25.0 grams of water?

2) How many grams are in 4.500 moles of Li2O?

3) How many molecules are in 23.0 moles of oxygen?

4) How many moles are in 3.4 x 1023 molecules of H2SO4?

5) How many molecules are in 25.0 grams of NH3?

6) How many grams are in 8.200 x 1022 molecules of N2I6?

1) n=m/MM

n=25 / (1.008*2) + 16

n=1.39mol

2) m=MM * n

m = ((6.941*2) + 16) * 4.5

m = 134.47g

3) molecules = n x 6.022 * 10^23

molecules = 23 * 6.022 * 10^23

molecules = 1.39 * 10^25

4) n = molecules / 6.022 * 10^23

n = 3.4 * 10^23/6.022 * 10^23

n = 0.56mol

5) n = m/MM

n = 25/14.01 + (1.008*3)

n = 1.467 ...

molecules = n * 6.022 * 10^23

molecules = 8.84 * 10^23

6) n = molecules / 6.022 * 10^23

n = 8.2 * 10^22/6.022 * 10^23

n = 0.136 ...

m = n * MM

m = 0.136 ... * ((14.01*2) + (126.9 * 6))

m = 107.49g