In a pharmaceutical preparation, 200g of rectified spirit is used as a solvent. According to PTB standards, what is the mass of water present?
Q1. In a pharmaceutical preparation, 200g of rectified spirit is used as a solvent. According to PTB standards, what is the mass of water present?
Answer: 9.0 g
Explanation: Rectified spirit is 95.5% ethanol and 4.5% water. 9g is 4.5% of 200g; 10g would be exactly 5%, which is incorrect.