Question

A 5.000 gram sample of lenthionine contains 0.6357 g carbon and 0.1070 g hydrogen, and the remainder is sulfur. The molar mass of lenthionine is 188.4 g/mol. Determine the chemical formula for lenthionine.

Answer 1

Answer: C2H4S5

Explanation:

Since the total mass is 5.000g

Mass of sulphur = 5.000-(0.6357+0.1070)

Mass of sulphur = 4.2573g

Using Empirical relation

C= 0.6357 H= 0.1070 S= 4.2573

Divide through by their molar mass to obtain the smallest ratio

C= 0.6357/12 H=0.1070/1 S=4.2573/32

C= 0.053 H= 0.1070 S= 0.133

Divide through by the smallest ratio (0.053)

C=0.053/0.053 H=0.1070/0.053 S=0.133/0.053

C=1 H=2 S=2.5

1:2:2.5 ,multiply through by 2 ,to obtain whole numbera

2:4:5

Therefore the empirical formula is C2H4S5. Thus only gives the ratio

Molecular formula is the chemical formula .

(Empirical formula) n = molecular formula

(C2H4S5)n = molar mass

[(12×2) + ( 1×4) +(32×5)]n = 188.4

188n=188.4

n= 1

Molecular formula = (C2H4S5)×1

Therefore the chemical formula of

lenthionine is C2H4S5