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Pharmacy calculations help

What weight of potassium permanganate is required to produce 130ml (millilitre) of solution such that 5ml (millilitre) of this solution diluted to 313ml (millilitre) gives a 0.6% w/v solution? Ensure your answer is in grams and correct to 2 decimal places.

A question for students in first year pharmacy

Idk what does it mean help please!!!

Reply 1

TypicalNerd

Original post by Hey_Hayley283

Not a pharmacist, but rather a chemistry undergrad

0.6% w/v means that per 100 ml of solvent, 0.6 grams of solute are dissolved in the mixture.

To make sense of the context:

130 ml of a potassium permanganate solution is being made. Of which, only 5 ml is actually used.

This 5 ml is then diluted to a solution of volume 313 ml and concentration 0.6% w/v.

The question wants you to find the mass of potassium permanganate in the original 130 ml of solution, but you first have to know how much solute was present in the 5 ml portion of this solution that was used.

Start by finding how much solute is present in the 313 ml of 0.6% w/v solution. This will be equivalent to the mass of solute in the 5 ml you started with (because dilution does not change how much solute is present in the solution).