How many equivalents of sodium are in a given volume of saline solution?

I can't figure out this problem-could you give me some hints? Here it is: If a patient is given 200 mL of physiological saline (0.9 grams of sodium chloride dissolved in 100 mL of solution), how many equivalents of sodium did the patient receive? The answer to the problem is 0.031 eq. but I don't know how to get that! I think it had to do with gram equivalent weight which is the atomic weight of the element divided by its valence. I know sodium has an atomic weight of 23 and a valence of 1. But that does not get me anywhere near the answer. Please help me!
Ally Browning 5/17/98

Ally, I think you're assuming you have 0.9 grams of sodium per 100 mL, but actually you have 0.9 grams of sodium CHLORIDE per 100 mL.

When you are faced with a perplexing problem you can often use a 'divide and conquer' strategy to break it down into several simpler problems. In this case, ask yourself:

• If there are 0.9 g of NaCl in 100 mL, how many g are in 200 mL?
• How many moles of NaCl is that, if one mole of NaCl weighs 58.5 g?
• How many moles of Na is that, if one mole of NaCl contains one mole of Na?
• How many equivalents of Na is that, if one mole of Na is one equivalent?

Author: Fred Senese senese@antoine.frostburg.edu

Copyright © 1997-2001 by Fred Senese
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Last Revised 02/23/18.URL: http://antoine.frostburg.edu/chem/senese/101-hidden/solutions/faq/equivalents-saline.shtml