I need to see where Im going wrong. Calculate the theoretical yield percentage of a reaction between sodium and water, if 25.

Please help and show your work. I need to see where Im going wrong.....

1.Calculate the theoretical yield percentage of a reaction between sodium and water, if 25.0 g of sodium react with excess water and if 15.5 L of gaseous hydrogen are collected at NTP conditions. 

2. Bromine can be obtained from the decomposition of calcium bromide by means of electrolysis. If 10.0 g of calcium bromide are dissolved in water before electrolysis and if 1.75 L of gaseous bromine is produced at 70 °C and 80 kPa, what is the theoretical yield percentage?

                                   CaBr2 à Ca + Br2