Acids typically come in 95-98% concentrated form, to save storage space. Pharmacists almost never need the 95% variety, so they have to dilute it to the required concentration.
If you dilute to half water, the concentration will be 47.5 % acid. But how do you dilute it to a standard % like 50%?
You need to use a ratio of water to acid in different concentrations, then scale to different %.
Hint: 95% acid = 95 parts acid/100 parts total, with 5 parts water/100 parts total
So in this example, the ratio of water to acid = 5/95
In a 50/50 solution, the water/acid ratio must = 1
- If you have 25cc of 95% acid solution, how much acid do you have in that solution? How much water?
- How much water must be added to this to get a 50% solution?
- How much must be added to get a 2% solution?
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