Super

4.00 x 10^23 molecules of h3po4 have an approximate mass of
a. 8g.
b. 65g.
c. 147 g.
d. 663g.

1) we can calculate the molecular weight of H₃PO₄
atomic mass  (H)=1 amu
atomic mass (P)=31 amu
atomic mass (O)=16 amu 

molecular weight (H₃PO₄)=3(1)+31+4(16)=98 amu.

1 mol (H₃PO₄)=98 g
1 mol= 6.022 * 10²³ molecules.

2) we calculate the mass of 4.00*10²³ molecules.

98 g6.022*10²³ molecules
x4.00*10²³ molecules

x=(98 g * 4.00*10²³ molecules) / 6.022*10²³ molecules≈65 g

65 g