What does (w/w)% mean?
The Correct Answer and Explanation is:
The abbreviation (w/w)% stands for weight/weight percent, which is a way of expressing the concentration of a substance in a mixture, specifically by weight. In this notation, “w” refers to the weight of a substance, and the percentage represents the weight of that substance relative to the total weight of the mixture, multiplied by 100.
To calculate the (w/w)%, the formula is:
[
\text{(w/w)\%} = \left( \frac{\text{Weight of solute}}{\text{Weight of solution}} \right) \times 100
]
For example, if you dissolve 10 grams of salt (the solute) into 90 grams of water (the solvent), the total weight of the solution is 100 grams. The (w/w)% concentration of salt in the solution would be:
[
\text{(w/w)\%} = \left( \frac{10\ \text{grams of salt}}{100\ \text{grams of solution}} \right) \times 100 = 10\%
]
This means that 10% of the total weight of the solution is made up of salt.
Explanation:
The (w/w)% notation is commonly used in chemistry, pharmaceuticals, and food science to provide a precise measurement of how much of a substance is present in a mixture, especially when both the solute and solvent are in solid form. Unlike volume-based measurements (such as % v/v, which is based on volume), (w/w)% focuses purely on weight. This is particularly useful when the densities of substances vary, as it avoids any confusion related to volume changes during mixing.
One of the key advantages of using (w/w)% is that it provides a consistent measure that is not affected by temperature or pressure, making it reliable for solid-liquid or solid-solid mixtures where weight is the most consistent property across various conditions.