# How would you make 100mL of a 12% glucose solution from a 20% stock solution?

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Expert Answers

gsenviro | Certified Educator

10 ml of a 12% solution from a 20% stock

We can use the relation: C1V1 = C2V2

where C1 and C2 are the concentrations of solutions and V1 & V2 are the volumes of respective solution.

Here, C1 = 12%, C2 = 20% and V1= 100 ml. We have to figure out how much of 20% solution is required to make a 12% solution.

Hence V2 = C1V1/C2 = (100x12)/20 = 60 ml

Therefore, we can use **60 ml of 20% stock** solution and add 40 ml (=100-60 ml) of water and mix everything to obtain a 100 ml 12% solution.

Hope this helps.