The given enthalpy of formation of magnesium oxide is -600KJ/mol, determine the enthalpy change when 3.8 grams of magnesium oxide is formed.
To determine the enthalpy change when 3.8 grams of magnesium oxide is formed, we need to first calculate the number of moles of magnesium oxide in 3.8 grams.
The molar mass of magnesium oxide (MgO) is 40.30 g/mol (24.31 g/mol for Mg and 16.00 g/mol for O).
Number of moles = Mass / Molar mass
Number of moles = 3.8 g / 40.30 g/mol
Number of moles = 0.094 mol
The enthalpy change when 0.094 mol of magnesium oxide is formed is given as -600 kJ/mol.
Therefore, the enthalpy change when 3.8 grams of magnesium oxide is formed is:
Enthalpy change = Number of moles x Enthalpy of formation
Enthalpy change = 0.094 mol x -600 kJ/mol
Enthalpy change = -56.4 kJ
So, the enthalpy change when 3.8 grams of magnesium oxide is formed is -56.4 kJ.