How many grams of sodium carbonate are present after the reaction is complete?

Need help with Chemistry, finding the number of grams of sodium in a reaction...

• A piece of sodium metal reacts completely with water as follows: 2Na(s)+@H2O(l) --> 2NaOH(aq)+H2(g) The hydrogen gas generated is collected over water at 25.0*C. The volume of the gas is 254 mL measured at 1.00 atm. Calculate the number of grams of sodium used in the reaction. (I know that vapor pressure of water at 25*C is 0.0313 atm). I'm stuck... so please show your work if you help me so I can see how to work this out. Thank you in advance!

• Answer:

  divide 2 accross the reaction to get the ratio of 1 mol of Na vs the rest. 1Na+1H2O > 1NaOH+0.5H2 now you need the exact mols of hydrogen used to find the number of mols of Na you used since now you know that 1mol of Na reacts to produce 0.5mol of H2. recall the universal gas law eqation for simple reactions. PV=nRT 254ml(1atm)=n(8.31)(273+25) 254=2476.38n n=.102mols (approx.) if 1 mol of H2 is 2 mol of Na then 0.102 mols of H2 is .204 mols of Na approx. now you know that mols is equal to mass in grams per molar mass. use equation, n=m/M .204=mx23 m=4.692g you may have to check this for yourself.