Hey guys and gals, this practice problem I started says that "a piece of sodium metal undergoes complete reaction with water. The gaseous product is collected over water at 25.5oC in a 246mL container at 745 torr. Provide a balanced equation for the reaction." Is this sodium metal just Na(s) or Na2CO3(aq) or what?
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Ambiguous reaction question. Help?
Started by Swenis
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use PV = nRT from the given pressure and volume info to solve for n moles of H2 gas. You know it takes 2 moles of Na for every 1 mole of H2 gas produced (from the balanced equation) so multiply moles H2 by 2. Now you know how many moles Na you have, which is = to the moles NaOH produced. You divide this (moles Na = moles NaOH) by how many L water you had, that will give you molarity NaOH.Swenis said:
The only question I have is about the amount of volume (L) I need to use for determining molarity since the problem says that I need to determine the conc. of the product if the sodium was added to 20mL of water. So does the 246mL container have any relevance to this problem or do I just use .02L (20mL)? Thanks DHG, you're awesome. 👍
The way I understood the question, if it's written word for word in the original post, was that the 246mL container was the collection container for the H2 gas, so that is the V you would use in PV=nRT for the gas part...Swenis said:
P=745 torr
V= 246mL
T=25C
R=whichever one you want to use, constant
n= unknown, moles of H2 gas produced
Once you get n moles from this, multiply it by 2 to get moles of Na (and therefore moles NaOH) ...divide this # by 20mL water (0.02L) to get molarity of NaOH solution.
