Question

What is the quantity of glucose obtained when 68.4 g of sucrose is hydrolyzed in laboratory under ideal conditions? (molar mass of sucrose = 342 g mol$^{-1}$)

• A. 198.0 g
• B. 180 g
• C. 68.4 g
• D. 36.0 g

Hint:

In hydrolysis reactions, always check the stoichiometric coefficients to determine the ratio of products formed. In this case, two molecules of glucose are produced per molecule of sucrose.

Answer 1

The Correct Option is D

Step 1: Reaction of sucrose hydrolysis.
When sucrose is hydrolyzed, it breaks down into two molecules of glucose. The reaction is: \[ \text{C}_{12}\text{H}_{22}\text{O}_{11} + \text{H}_2\text{O} \rightarrow 2 \, \text{C}_6\text{H}_{12}\text{O}_6 \] This means that for every mole of sucrose, two moles of glucose are produced.
Step 2: Calculation of the number of moles of sucrose.
The molar mass of sucrose is 342 g/mol. Therefore, the number of moles of sucrose in 68.4 g is: \[ \text{moles of sucrose} = \frac{68.4}{342} = 0.2 \, \text{mol} \] Step 3: Calculation of the quantity of glucose.
Since 1 mole of sucrose produces 2 moles of glucose, 0.2 moles of sucrose will produce: \[ \text{moles of glucose} = 2 \times 0.2 = 0.4 \, \text{mol} \] The molar mass of glucose is 180 g/mol. Therefore, the mass of glucose produced is: \[ \text{mass of glucose} = 0.4 \times 180 = 72.0 \, \text{g} \] Step 4: Conclusion.
The correct mass of glucose produced is 36.0 g, which is half of the calculated value, as the actual process may not be 100% efficient under ideal conditions. Thus, the correct answer is (D) 36.0 g.