posted by Brianna .
What is the limiting reagent when 10.8 g water reacts with 4.7 g Na to produce NaOH and H2?
The first step to this problem is to write out reaction and balance it.
H2O + Na ---> NaOH + H2
The balance reaction looks like the following
2H2O +2 Na--->2NaOH + H2
This lets you know that the mole ratio between H2O and Na for this reaction to proceed must must be equal.
Convert grams of each to moles
10.8 g of H2O/18 g of H20/mole = number of moles H2O
4.7 g of Na/23.0 g of Na/mole = number of moles of Na
The compound with the least number of moles is the limiting reagent.