When 1.00g of liquid water (MW = 18) is reduced from H2 and O2 at a constant temperature (25C) and pressure (1 atm) 15.8 kilojoules are produced. What is the molar heat of formation of liquid water, in kilojoules?

can someone please show how they do this i'm soo lost with this one.

Clapton's right, but if I remember correctly, you don't multiply by 2mol, rather, you divide by it. -15kJ is the kJ for the formation, which is what we want to look at.

2H2 + O2 -> 2H2O = -15kJ

But this is the heat of formation of 2 moles of H20. Therefore, the heat of formation for 1 mol is just half of that. Answer is -15/2kJ, or -7.5kJ.

Clapton's right, but if I remember correctly, you don't multiply by 2mol, rather, you divide by it. -15kJ is the kJ for the formation, which is what we want to look at.

2H2 + O2 -> 2H2O = -15kJ

But this is the heat of formation of 2 moles of H20. Therefore, the heat of formation for 1 mol is just half of that. Answer is -15/2kJ, or -7.5kJ.

No, I'm sure you multiply. The heat of formation is given for 1 mole of water. In the balanced equation, there are 2 moles. They give you H2 and 02. For every mole of O2, there has to be 2 moles of H2 in order to make water. Two waters have to be formed from what they give you.

No, I'm sure you multiply. The heat of formation is given for 1 mole of water. In the balanced equation, there are 2 moles. They give you H2 and 02. For every mole of O2, there has to be 2 moles of H2 in order to make water. Two waters have to be formed from what they give you.