2al(s) + fe2o3(s) → al2o3(s) + 2fe(s) t
he δhf for fe2o3(s) = -824.3 kj/mole.
the δhf for al2o3(s) = -1675.7 kj/mole.
finish the equation.
δhrxn = [(1) ( kj/mole) + (2) ( kj/mole)] - [(1) ( kj/mole) + (2) ( kj/mole)]

ΔHrxn = [(1) -1675.5 ( kJ/mole) + (2) 0 ( kJ/mole)] - [(1) -824.3 ( kJ/mole) + (2) 0 ( kJ/mole)]

Explanation:

ΔHrxn = 2ΔHf (Al₂O₃)  - ΔHf (Fe₂O₃)

Remember that for pure elements in their standard state of temperature and pressure by definition their standard heats of formation are zero.

ΔHrxn = 2(-1675.7) - (-824.3) kJ/mol

ΔHrxn = 2527 kJ/mol

answer; i believe that the correct answer is (a) potassium(k)

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.