While preparing 250 mL of 2 %(w / v) solution, a pharmacist mistakenly used only 4.5 g of drug

Name: Problem 34, Chapter 3: Essential Math and Calculations for Pharmacy Technicians
Uploaded: 2023-03-04T06:58:52-08:00
Duration: 1 min 13 s
Channel: Shalini Tyagi
Description: While preparing 250 mL of 2 %(w / v) solution, a pharmacist mistakenly used only 4.5 g of drug. How many more milligrams of this drug are needed to get the correct strength?

step 1 number of capsules. So that will be given by mass of capsules dispensed divided by mass of one c

Question

While preparing $250 \mathrm{~mL}$ of $2 \%(w / v)$ solution, a pharmacist mistakenly used only $4.5 \mathrm{~g}$ of drug. How many more milligrams of this drug are needed to get the correct strength?

   While preparing $250 \mathrm{~mL}$ of $2 \%(w / v)$ solution, a pharmacist mistakenly used only $4.5 \mathrm{~g}$ of drug. How many more milligrams of this drug are needed to get the correct strength?

Essential Math and Calculations for Pharmacy Technicians

Indra K. Reddy,… 1st Edition

Chapter 3, Problem 34

Instant Answer

Solved by Expert Shalini Tyagi

03/04/2023

Step 1

To find the amount of drug needed for a $2 \% (w/v)$ solution, we first convert the percentage to a decimal: $2 \% = 0.02$. Then, we use the formula: Amount of drug (g) = Percentage (decimal) $\times$ Volume of solution (mL) Amount of drug = $0.02 \times 250 Show more…

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While preparing $250 \mathrm{~mL}$ of $2 \%(w / v)$ solution, a pharmacist mistakenly used only $4.5 \mathrm{~g}$ of drug. How many more milligrams of this drug are needed to get the correct strength?

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Key Concepts

Weight/Volume Percent Solutions

This concept refers to the concentration expressed as a percentage of weight (mass) of solute per volume of solution. For a 2% (w/v) solution, it means that there are 2 grams of solute in every 100 mL of the solution, which is fundamental for determining the required mass of solute for any given volume.

Calculation of Solute Mass in Solution Preparation

This involves computing the total amount of solute necessary by applying the concentration to the intended volume of the solution. It includes setting up and solving a proportion based on the established concentration, then comparing the required amount with the amount already used to identify any discrepancy.

Unit Conversion

Converting units is crucial in any calculation involving measurements. In this context, converting grams to milligrams is necessary to express the final answer in the desired unit, ensuring that all measured quantities are in a consistent and appropriate form.

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