Dimethyl ether, a useful organic solvent, is prepared in two steps. In the first step, carbon dioxide and hydrogen react to form methanol and water: CO₂(g) + 3H₂(g) [tex]\rightarrow[/tex] CH₃OH (l) + H₂O(l); ΔH = -131.kJ In the second step, methanol reacts to form dimethyl ether and water: 2CH₃OH (l) [tex]\rightarrow[/tex] CH₃OCH₃(g) + H₂O (l); ΔH = 8.kJCalculate the net change in enthalpy for the formation of one mole of dimethyl ether from carbon dioxide and hydrogen from these reactions.Round your answer to the nearest kj.

Question

contestada

Respuesta :

baraltoa baraltoa · Answer 1 · 2019-11-08T15:12:41+01:00

Answer:

ΔH = - 254 kJ

Explanation:

The final equation for the enthalpy of formation we want to calculate is:

2 CO₂ (g) + 6 H₂(g) -------------- CH₃OCH₃ (l) ΔH = ?

Notice that if we take the 2 times the first reaction and add the second , by Hess's law we will add the enthalpy changes to obtain our desired ΔH .

( CO₂(g) + 3H₂(g) CH₃OH (l) + H₂O(l); ΔH = -131.kJ) x 2

2CO₂(g) + 6H₂(g) --------- 2CH₃OH (l) + 2 H₂O(l); ΔH = -262.kJ

2CH₃OH (l) --------- CH₃OCH₃(g) + H₂O (l); ΔH = 8.kJ

_____________________________________________________

2CO₂(g) + 6H₂(g) ----------- CH₃OCH₃(g) + 3H₂O (l); ΔH = -254 kJ