I don't see an arrow.
This is a limiting reagent problem; I know that because amounts for BOTH reactants are given.
Convert 5.70 g O2 and 5.70 g H2 to moles. moles = grams/molar mass.
First O2 and ignore H2.
Convert moles O2 to moles H2O using the coefficients in the balanced equation.
Next H2 and ignore O2.
Convert moles H2 to moles H2O using the coefficients in the balanced equation.
You have two answers for the same product; both can't be correct. The correct value, in limiting reagent problems, is ALWAYS the smaller value and the reagent producing that value is the limiting reagent.
Now convert the moles (the smaller value) to grams. g = moles x molar mass.
Here is a worked example of a simple stoichiometry problem. It will solve all of your simple stoichiometry problems.
http://www.jiskha.com/science/chemistry/stoichiometry.html
What is the largest amount of H2O in grams that can be formed when 5.70 g of H2 reacts with 5.70 g of O2, based on the balanced reaction below.
2 H2 + O2 2 H2O
1 answer