I NEED HELP ASAP ! 1. How many molecules are in 643.21 grams of
Mg3(PO4)22
2. How much space (Liters) does 4.061 x 10-24
molecules of H202 take up?
3. How many H20 atoms are in 479.3 grams of
H20 gas?
4. How many grams does 80.34 L of Ca(NO3)2
weigh?
5. How many Liters of space does 893.7 grams
of CO2 take up?
6. How many grams are in 5139 x10425
molecules of Al(OH)3

1.

643.21g  1 mol  6.022^23

262.87 g   1 mol

= 1.4735E24     [Mg3(PO4)2]

2.

4.061x10^24          1mol                22.4 (L)  

6.022^23       1mol

= 151 liters H2O2

3.

479.3g   1 mol   6.022^23

18.02g    1mol

= 1.60E25 H20 atoms

4.

80.34L   1mol       164.1

22.4L       1mol

588.6g   Ca(NO3)2

5.

893.7g   1mol       22.4

44.01g   1mol

= 427 L CO2 or 427.4

6.

5.39 x 10^25     1mol     78.01

6.022^23    1mol

= 6980g Al(OH)3

hope this helps!! :)

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.