Tutorial for Ray Only

Item number 5 Formula Mass Computations (in amu) – Table 2

MgO

Mg = 24.305 O = 15.999

Mr = 24.305 + 15.999 = 40.304

K2S

K = 39.098 S = 32.065

Mr = 2(39.098) + 32.065 = 110.26 amu

C3H8O3

C = 12.011 H = 1.008 O = 15.999

Mr = 3(12.011) + 8(1.008) + 3(15.999) = 92.09 amu

Ca (NO3)2

Ca = 40.078 N = 14.007 O = 15.999

Mr = 40.078 + 2[14.007 +3(15.999)] = 164.09 amu

Mg3 (PO4)2

Mg = 24.305 P = 30.964 O = 15.999

Mr = 3(24.305) + 2 [30.964 + 4(15.999)] = 262.84 amu

C6H2CH3 (NO2)3

C = 12.011 H = 1.008 O = 15.999 N = 14.007

Mr = 7(12.011) +5(1.008) + 3[14.007 +2(15.999)] = 227.1 amu

Pt (NH3)2Cl2

Pt = 195.084 N = 14.007 H = 1.008 Cl = 35.453

Mr = 195.084 + 2[14.007+ 3(1.008)] = 300.1 amu

Fe (ClO4)2

Fe = 55.845 Cl = 35.453 O = 15.999

Mr = 55.845 + 2 [35.453 + 4(15.999)] = 254.74 amu

Na2CO3 • 10H2O

Na= 22.99 C = 12.011 O = 15.999 H = 1.008

Mr = 2(22.99) + 12.011 + 3(15.999) + 10[2*1.008 + 15.999] = 286.1 amu

MgSO4 • 7H2O

Mg = 24.305 S = 32.065 O = 15.999 H = 1.008

Mr = 24.305 + 32.065 + 4(15.999) + 7 [2*1.008 + 15.999] = 246.5 amu