I need a solution that the concentration is 0.06533g/L in a 100.00mL solution bu

Question

I need a solution that the concentration is 0.06533g/L in a 100.00mL solution but I must have 4 sig.figs. and our scales only are good to the ten thousanths. So, I thought I would make a solution that is 10.00mL, and pipet (using a 10.00mL pipet) it into my 100.00ml volumetric flask. I used M1V1=M2V2 and got

(x)(10.00mL)=(0.06533g)(100.00mL), where x=0.6533g/L. Great 4 sig. figs.!! But here is where I am confused... do I use 0.06533g of my solute and dissolve it in 10.00mL of distilled water and then pipet that into my 100.00mL flask, with will be filled up with distilled H20 after I add my other ingredients. OR am I supposed to dilute that into 100.00mL first then just take 10.00mL of that... Mass concentration confusion!!!

Please help!! I assure you this is just one problem, although it is long. I just need help figuring out how to do this.

Explanation / Answer

So the concentration g/L means that you have 0,06533grams of solute in a 1L of solution, and you need that in a 100ml. You have to do a 3 rule

0,06533g solute ----------- 1L solution

X g   solute ------------ 0,1L solution

X= 0,1*0,06533/1= 0,006533grams solute

Because you have a very small amount that you have to weight, you can make a concentrated solution and then delude to the concentration that you want.

So you calculate the concentration of the concentrated solution with the relation M1V1=M2V2. When you use that relation you calculate that if you add 10ml of a solution of concentration 0,6533g/L to a flask of 100ml of volume and add the enough water (90ml) to get to the 100ml you will have the solution with the concentration of 0,06533g/L.

So this means that you have to prepare the solution of 10ml with 0,6533g of solute, and that solution all 10ml you will put in a flask of 100ml volume and the other 90ml you will fill it with water.

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