How
many moles of hydrogen gas will form if 0.35 moles of Na reacts with an
excess of water?

0.8 moles

Explanation:

2H2+O2 —›2H2O

Since , from given balanced chemical Equation.

2moles of H2 produce 2 moles of Water

So,

2moles H2= 2moles H2O

1moles H2= 1 mole of H2O

For 0.8 mole of H2O, multiply both sides by 0.8

0.8 H2=0.8 H2O

0.8 mole of H2= 0.8 mole H2O

So answer is 0.8 moles

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.

i believe the answer is 5,000