Hydrogen peroxide decomposes according to the following thermochemical reaction
H2O2 --> H2O +1/2 O2 ; H= -98.2 kJ
calculate the change in enthalpy when 1.00 g of hydrogen peroxide decomposes.
what part of a mole of H2O2 is one gram?
-11.5
To calculate the change in enthalpy (ΔH) when 1.00 g of hydrogen peroxide decomposes, you need to use stoichiometry and the given enthalpy change (ΔH = -98.2 kJ).
First, convert the mass of hydrogen peroxide (1.00 g) to moles. You can use the molar mass of hydrogen peroxide, which is 34.0147 g/mol. Divide the mass by the molar mass to get the number of moles:
1.00 g H2O2 ÷ 34.0147 g/mol = 0.0294 mol H2O2
According to the balanced chemical equation, 1 mole of hydrogen peroxide decomposes to give 1 mole of water and 1/2 mole of oxygen gas. Therefore, the reaction is in a 1:1:1/2 ratio.
Now, you can calculate the change in enthalpy using the stoichiometric coefficients and the given enthalpy change:
ΔH = (0.0294 mol H2O2) x (-98.2 kJ/1 mol H2O2)
= -2.880 kJ
Therefore, the change in enthalpy when 1.00 g of hydrogen peroxide decomposes is -2.880 kJ.