Solve
Use dilution basics:
[
% (w/v)=\frac{\text{grams of solute}}{\text{mL of solution}}\times 100
]
a) For 100 mL of 10% (w/v) glucose
10% (w/v) means 10 g glucose in 100 mL solution.
✅ Required glucose = 10 g
b) Serial dilution
I) First tube:
You transfer 1 mL of 10% stock into 9 mL water
Final volume = (1+9=10) mL → this is a 10-fold dilution.
Final volume = (1+9=10) mL → this is a 10-fold dilution.
[
C_2 = C_1 \times \frac{V_1}{V_2}
=10% \times \frac{1}{10}
=1%
]
✅ Concentration in first tube = 1% (w/v)
II) Second tube:
Now transfer 1 mL of first tube (1%) into 9 mL water again (another 10-fold dilution):
[
C_2 = 1% \times \frac{1}{10}=0.1%
]
✅ Final concentration = 0.1% (w/v)
Final answers:
- (a) 10 g
- (b)(I) 1% (w/v)
- (b)(II) 0.1% (w/v)
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