Calculate the formula mass for each compound. a. NO2 b. C4H10 c. C6H12O6 60. Calculate the formula mass for each compound. a. MgBr2 b. HNO2 c. CBr4 d. Cr (NO3) 3

The formula mass of a molecule (also known as formula weight) is the sum of the atomic weights of the atoms in the empirical formula of the compound.

a. NO2

N = 14

O = 16

NO2 = 14 + (16 * 2) = 46 amu

b. C4H10

Empirical formular = C2H5

C = 12

H = 1

C2H5 = (12*1) + (1*5) = 12 + 5 = 17 amu

c. C6H12O6

Empirical formular = CH2O

C = 12

H = 1

O = 16

C2H5 = 12 + (1*2) + 16 = 30 amu

d MgBr2

Mg = 24

Br = 80

MgBr2 = 24 + (80*2) = 184 amu

e. HNO2

H = 1

N = 14

0 = 16

HNO2 = 1 + 14 + (16*2) = 47 amu

f. CBr4

C = 12

Br = 80

CBr4 = 12 + (80*4) = 332 amu

g. Cr (NO3) 3

Cr = 52

N = 14

O = 16

Cr (NO3) 3 = 52 + 3[14 + (3*16) ] = 238 amu