Question G5 part c

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Athena L 1B
Posts: 59
Joined: Fri Sep 28, 2018 12:18 am

Question G5 part c

Postby Athena L 1B » Thu Oct 04, 2018 10:43 am

G5: 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 (c) 50.0 mg of Na2CO3?

I understand how to do parts a and b with moles, but for part c I'm not sure what steps to do.

Camille Marangi 2E
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

Re: Question G5 part c

Postby Camille Marangi 2E » Thu Oct 04, 2018 12:03 pm

It is just one extra step compared to parts a and b.

50.0mg means 50.0 milligrams of sodium carbonate and is also equivalent to .05 grams of Na2CO3.
From there you convert the grams to moles using the molar mass, 105.988 g/mol, which will give you 4.72 x 10^-4 moles of sodium carbonate.

Then, like in parts a and b, you divide the moles by the .08 M you calculated in the first two steps to get the final answer, .00592 L or 5.92 mL.

Hope this helps!

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