Question

The molecular formula for glycine is $C_{2}H_{5}O_{2}N$. What would be the molecular formula for a linear oligomer made by linking ten glycine molecules together by condensation synthesis?

• A. $C_{20}H_{50}O_{20}N_{10}$
• B. $C_{20}H_{32}O_{11}N_{10}$
• C. $C_{20}H_{40}O_{10}N_{10}$
• D. $C_{20}H_{68}O_{29}N_{10}$

Hint:

Formula for a linear polymer: $(n \times \text{Monomer}) - ((n-1) \times H_{2}O)$.

Answer 1

The Correct Option is B

Step 1: Raw Calculation
Ten glycine molecules ($10 \times C_{2}H_{5}O_{2}N$) = $C_{20}H_{50}O_{20}N_{10}$.

Step 2: Analysis of Condensation
Linking 10 monomers in a linear chain requires the formation of 9 peptide bonds. Each bond formation releases one water molecule ($H_{2}O$).

Step 3: Subtraction
Total $H_{2}O$ lost = $9 \times H_{2}O = H_{18}O_{9}$.
Final formula = $(C_{20}H_{50}O_{20}N_{10}) - (H_{18}O_{9}) = C_{20}H_{32}O_{11}N_{10}$.

Step 4: Conclusion
The correct formula is $C_{20}H_{32}O_{11}N_{10}$. Final Answer: (B)