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### Question from textbook

Posted: Sun Nov 04, 2018 8:48 pm

A student prepared a solution of sodium carbonate by adding 2.111 g of the solid to a 250.0-mL volumetric flask and adding water to the mark. Some of this solution was transferred to a buret. What volume of solution should the student transfer into a flask to obtain (a) 2.15 mmol Na+; (b) 4.98 mmol CO3^2-; (c) 50.0 mg Na2CO3?

### Re: Question from textbook

Posted: Sun Nov 04, 2018 9:21 pm
First, use the 2.111g Na2CO3 and the 250.0mL and find the molarity. I got .07980mol/L.
For part a, take the 2.15mmol Na+ ion and convert into moles. There are two Na+ ion per Na2CO3 molecule, so using dimensional analysis you find out how many moles of Na2CO3 you need. Using the molarity we found, we can convert that into how many liters of the solution we need.
Using this process, you can find part b and part c. It's just a lot of dimensional analysis.

### Re: Question from textbook

Posted: Mon Nov 05, 2018 9:46 pm
Use 2.111g Na2CO3 and the 250.0mL to get the molarity. 0.08mol/L.
Take the 2.15mmol Na+ ion and convert into moles. There are two Na+ ion per Na2CO3 molecule. Using the molarity, we can convert that into how many liters of the solution we need.
you can find the answers for part c by the same way