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What is the difference between V/V, W/V and W/W?
There are many ways to measure chemicals – the reason being is that each chemical measurement will affect the result of the chemical usage.
Volume-Volume (v/v)
Volume concentration of a solution as % v/v which stands for volume over volume. This is used when both substances in a solution are liquid.
For example, when 50ml of sulphuric acid is diluted with 50ml of water, there will be 50ml of sulphuric acid in a total volume of 100ml. Therefore, we would express the concentration of this solution as sulphuric acid 50% v/v.
V/V
Weight-Volume (w/v)
Mass concentration of solution is expressed as % w/v for weight in volume. This can be used when a solid chemical is dissolved in liquid as well as liquid/liquid.
If 50 grams of sulphuric acid is used to make up a total volume of 100ml then a 50% w/v solution of sulphuric acid has been made. This can also be expressed as 500gms/ltr which is a format often used on chemicals labels to show concentration of active ingredients.
V/V
Weight-Weight (w/w)
Weight concentration of a solution is expressed as % w/w. This stands for weight in weight. In this case, the volume of each chemical is disregarded and only the weight is used.
So, if the total weight of a 100g solution is made of 50g sulphuric acid in 50g of water, then we would express this as sulphuric acid 50% w/w.
V/V
An important thing to remember is it’s always best to add the concentrate to water when diluting. Make sure you have the correct volume of water required and then add the concentrate to this.
Click here to understand how dosing gear reacts differently depending on doses and waterflows.
