How many liters of h2 are required to form 5 moles of h2o at stp?

steps...

1) convert mass H2O to moles H2O

2) use coefficients of balanced equation to convert to moles O2

3) convert moles O2 to L O2.

solution...

10.5 g H2O x (1 mole H2O / 18.0 g H2O) = 0.583 moles H2O

from the balanced equation, 1 mole O2 --> 2 moles H2O.. therefore...

0.583 moles H2O x (1 mole O2 / 2 moles H2O) = 0.292 moles O2

from here you can either use the specific form of the ideal gas law for STP...

0.292 moles O2 x (22.4 L O2 / mole O2) = 6.54 L O2

or you can use the more general form of the ideal gas law...

V = nRT/P = (0.292 moles) x (0.0821 Latm/moleK) x (273 K) / (1 atm)

V = 6.54 L O2

Hope this helps!

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.