If 75 g of active ingredient powder is mixed with 250 mL normal saline, what is the final concentration $(w / v)$?
Answer (2)
Define concentration (w/v) as the mass of solute (g) per 100 mL of solution.
Use the formula: Concentration (w/v) = volume of solution (mL) mass of solute (g) × 100 .
Substitute the given values: Concentration (w/v) = 250 mL 75 g × 100 .
Calculate the final concentration: 30 .
Explanation
Understanding the Problem We are given that 75 g of active ingredient powder is mixed with 250 mL normal saline. We need to find the final concentration (w/v). Concentration (w/v) is defined as the mass of solute (in grams) per 100 mL of solution.
Setting up the Calculation To find the concentration (w/v), we use the formula: Concentration (w/v) = volume of solution (mL) mass of solute (g) × 100 In this case, the mass of the solute (active ingredient powder) is 75 g, and the volume of the solution (normal saline) is 250 mL.
Calculating the Concentration Substitute the given values into the formula: Concentration (w/v) = 250 mL 75 g × 100 Now, we perform the calculation: Concentration (w/v) = 250 75 × 100 = 0.3 × 100 = 30 So, the final concentration is 30 (w/v).
Final Answer The final concentration (w/v) of the solution is 30.
Examples
In pharmacology, calculating weight/volume (w/v) concentration is crucial for preparing medications. For instance, a pharmacist needs to determine the amount of active ingredient to dissolve in a specific volume of solution to achieve the desired concentration for a drug. This ensures accurate dosing and effective treatment. Understanding w/v concentration is also important in environmental science, where scientists measure the concentration of pollutants in water samples to assess water quality and environmental impact. By calculating the w/v concentration, they can determine the amount of pollutant present per unit volume of water, which helps in monitoring and managing environmental pollution.
The final concentration (w/v) of the active ingredient in the saline solution is 30 g per 100 mL. This is calculated using the formula for weight/volume concentration. Here, 75 g of solute in 250 mL of solution results in a concentration of 30 g/100 mL.
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