How many mL of a 1:60 stock solution of Ephedrine Sulphate would be needed to make 30 mL of a product to treat nasal congestion containing 0.25 % Ephedrine Sulphate?

Question

BlackTom AI · Accepted Answer

A 0.25% w/v solution equals 0.25 g of drug per 100 mL, so use that to find the mass required, then use the 1:60 stock strength (1 g in 60 mL) to find the volume needed.

1) Relevant knowledge points and concepts
- Percent strength w/v: X% w/v = X g per 100 mL. Thus 0.25% = 0.25 g/100 mL.
- Ratio strength 1:60 means 1 g of active in 60 mL of solution, so concentration = 1/60 g per mL.
- Mass required = desired concentration × final volume. Volume of stock required = mass required ÷ stock concentration.

2) Step-by-step reasoning
- Find mass of ephedrine sulphate needed in 30 mL of final product.
- Convert stock ratio to g/mL and compute volume that contains that mass.

3) Calculations (all intermediate steps)
- Mass required in 30 mL:
  0.25 g per 100 mL ⇒ mass = (0.25 g / 100 mL) × 30 mL
  mass = 0.0025 g/mL × 30 mL = 0.075 g
- Stock concentration:
  1 : 60 ⇒ 1 g in 60 mL ⇒ concentration = 1/60 g/mL ≈ 0.0166667 g/mL
- Volume of stock to supply 0.075 g:
  volume = mass / concentration = 0.075 g ÷ (1/60 g/mL) = 0.075 × 60 mL = 4.5 mL

4) Why the correct answer is correct
The stock delivers 0.0166667 g per mL, so 4.5 mL of stock gives 4.5 × 0.0166667 = 0.075 g, exactly the amount required for a 0.25% strength in 30 mL. Thus 4.5 mL is the required volume.

5) Why other options are incorrect (brief)
- 2.5 mL ⇒ 2.5 × (1/60) = 0.0417 g (too little)
- 3.5 mL ⇒ 0.0583 g (too little)
- 4.0 mL ⇒ 0.0667 g (too little)
- 5.0 mL ⇒ 0.0833 g (too much)

6) Conclusion
The correct volume of 1:60 stock solution required is 4.5 mL, matching answer d. 4.5 mL.

How many mL of a 1:60 stock solution of Ephedrine Sulphate would be needed to make 30 mL of a product to treat nasal congestion containing 0.25 % Ephedrine Sulphate?单项选择题

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