Calculate the mass of NaCl needed to bring sodium concentration to 0.139 M?

[Modrisco]

A person suffering from Hypothermia has a sodium ion concentration in the blood of 0.114 M and a total blood volume of 5.1 L. What mass of sodium chloride needs to be added to the blood to bring sodium ion concentration up to 0.139 M? (assuming no change in blood volume)

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Atomic weight of Na: 230 g

Mass of sodium in blood:
230 x 0.114 M = 26.22 g

Mass of sodium needed:
230 x 0.139 = 32.97
32.97 - 26.22 = 5.72 g

5.72 g of sodium needed

Ratio of mass in NaCl
Mass of Cl : Mass of Nacl
35.453 g : 230 g
1 : 6.49

Mass of Cl in NaCl when Na is 5.72 g:

230/35.453 = 5.72/x
230x = 5.72(35.453)
230x = 202.79
x = 202.79/230
x = 0.88g


Mass of NaCl needed:
0.88g + 5.72g
= 6.6 g



Mass of NaCl needed 6.6g


Is this correct?

 

[HallsofIvy]

Looks good. Although, I would have done the last calculation slightly differently:
Mass of Cl : Mass of Nacl
35.453 g : 230 g

so the total mass of (one mol of) NaCl is 35.453+ 230= 265.453 g. That is a ratio of NaCl to Na of 265.453/230= 1.154 so the the total mass of NaCl to produce 5.72 g of sodium is (1.154)(5.72)= 6.6 g of NaCl. exactly what you got.

 

[Modrisco]

Thank you very much:) I prefer your way haha

If you're a yahoo question answerer, you can copy and paste that answer to the same question that I asked 3 times (no one wanted to answer) and I will give you best answer for each one:)
thank you

Here is the links to the same question:

http://uk.answers.yahoo.com/questio...U3.P7tYgBgx.;_ylv=3?qid=20120430180751AAuGj9N

http://uk.answers.yahoo.com/questio...DhT6K4kgBgx.;_ylv=3?qid=20120430133241AAhfri9

http://uk.answers.yahoo.com/question/index;_ylt=AiO70AMxfXqdmWoboJrzBPkgBgx.;_ylv=3?qid=20120430131115AA32Mjs


A lannister, always pays his debts.

 

[Modrisco]

Just realized I made a massive error in the atomic weight of Na, it's 23g not 230g hahaha

 

[Borek]

Just realized I made a massive error in the atomic weight of Na, it's 23g not 230g hahaha

That was the first thing that caught my eye.