Insulin contains exactly $3.4\%$ sulfur by mass. The minimum possible molecular weight of insulin is

Question

Insulin contains exactly $3.4\%$ sulfur by mass. The minimum possible molecular weight of insulin is approximately (Atomic weight of $\mathrm{S} = 32 \mathrm{~u}$)

Professor PC Thomas Classes · Answer

(a) : For the molecular weight to be a minimum, one molecule of insulin must contain at least one sulfur atom. $3.4\%$ sulfur by mass means that $3.4 \mathrm{~g}$ of sulfur is present in $100 \mathrm{~g}$ of insulin. Therefore, $32 \mathrm{~g}$ of sulfur (mass of one mole of S atoms) will be present in $\frac{100}{3.4} 	imes 32 = 941.17 \mathrm{~g}$ of insulin. Thus, the minimum molecular weight is approximately $941 \mathrm{~u}$.