2H2(g)+O2(g) ---> 2H2O(l)
delta H= -572kJ/mole of O2
Calculate the amount of heat evolved when 10g of hydrogen are burned in excess oxygen.
572 kJ/mol O2 = 572 kJ/32g O2 = 572 kJ/4g H2.
572 kJ x (10/4) = ? kJ.
To calculate the amount of heat evolved when 10g of hydrogen (H2) are burned in excess oxygen (O2), we first need to determine the amount of moles of hydrogen.
Step 1: Calculate the moles of hydrogen.
To do this, we can use the molar mass of hydrogen, which is approximately 2 g/mol.
Moles of hydrogen = Mass of hydrogen / Molar mass of hydrogen
Moles of hydrogen = 10 g / 2 g/mol
Moles of hydrogen = 5 moles
Step 2: Use the balanced chemical equation and the given delta H value to determine the amount of heat evolved.
From the balanced chemical equation:
2H2(g) + O2(g) --> 2H2O(l)
We can see that for every 2 moles of hydrogen gas used, 572 kJ of heat is evolved.
So, for 5 moles of hydrogen gas used, the amount of heat evolved can be calculated using a proportion:
Heat evolved = (Moles of hydrogen / Moles of H2 in the balanced equation) × delta H
Heat evolved = (5 moles / 2 moles) × (-572 kJ)
Heat evolved = -1430 kJ
Therefore, when 10g of hydrogen are burned in excess oxygen, the amount of heat evolved is -1430 kJ. The negative sign indicates that the reaction is exothermic, meaning heat is released.