Percentage calculation is very useful in pharmacy and pharmaceutical calculations to measure the number of grams contained in 100 mL of solution. Which is expressed by Percent Weight in Volume (%w/v).
Percentage Calculation Formula
To determine the percentage of X, we have to divide the value (X) by the total value (Y) and then multiply the resultant by 100.
Percentage (%) = X/Y ×100%
Percentage Calculation Example
1. Express 1:2000 as a percentage strength.
1 part/2000 parts = X parts/100 parts.
So, X = 1 × 100/2000 = 0.05%
2. Express 0.5% w/w as a ratio strength.
0.5 g/100 g = 1 part/X parts.
X = 100 × 1/0.5
X = 200
Therefore, the ratio strength = 1:1000
3. Express 5 ppm as a percentage strength.
5 ppm = 5 part per million = 5:1000000
So, 5 part/1000000 = X parts/100 parts
X = 5 × 100/1000000 = 0.0005%
Related: Ratio and Proportion Calculation in Pharmacy
Pharmaceutical Percentage Calculation
1. Express 1 in 200 w/v solution of potassium permanganate as a percentage.
1/200 = X / 100
X = 1 × 100/200 = 0.5% w/v
2. How many grams of a drug should be used to prepare 250 g of a 10% w/w solution?
Let X be the weight of the drug needed:
So, X/250 = 10 g/100 g
X = 10 × 250/100 = 25 g
3. Express 1.8 g of sodium chloride, made up to 200 mL with water, as a percentage.
1.8/200 = X/100
X = 100 × 1.8/200 = 0.9%
Post a Comment