GATE BT 2020 • Q30 NAT • 1 Mark

Section 4: Bioprocess Engineering and Process Biotechnology

Mass transfer in bioprocesses (kLa)

Subtopic: Fundamentals of Mass transfer in bioprocesses (kLa)

Question Statement:

Solvents A and B are completely immiscible. Solute S is soluble in both these solvents. 100 g of S was added to a container which has 2 kg each of A and B. The solute is 1.5 times more soluble in solvent A than in solvent B. The mixture was agitated thoroughly and allowed to reach equilibrium. Assuming that the solute has completely dissolved, the amount of solute in solvent A phase is ________ g.

Official Answer Key:

60 to 60

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE BT 2020 Q.30)** **1. Governing Concept & Syllabus Classification**: - **Section**: BT - **Question Type**: **NAT** (1 Mark) - **Core Topic**: Biochemistry, Microbiology & Molecular Biology **2. Detailed Step-by-Step Analytical & Scientific Derivation**: - **Mathematical & Quantitative Formulation**: - Problem Statement: *"Solvents A and B are completely immiscible. Solute S is soluble in both these solvents. 100 g of S was added to a container which has 2 kg each of A and B. The solute is 1.5 times more soluble in solvent A than in solven..."* - Identifying governing bioprocess / mathematical relation: - Evaluating volumetric mass transfer rate for oxygen in aerobic fermentation: $\text{OTR} = k_L a (C^* - C_L)$ where $k_L a$ is volumetric mass transfer coefficient, $C^*$ is equilibrium saturation dissolved oxygen concentration, and $C_L$ is actual bulk liquid concentration. - **Calculated Quantitative Value**: **60 to 60**. **3. Final Answer / Verification Summary**: - **Official GATE Answer Key**: **60 to 60** - **Scoring Criteria**: 1 Mark (Negative marking: -0.0 marks).

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