Anyone know this question

12

Explanation:

HClO4 is the “hydrated” form of Cl2O7 and

H3PO4 is the “hydrated” form of P4O10

so I split the reaction into two halves:

HClO4 => Cl2O7

2 HClO4 => Cl2O7 (balance the Cl)

2 HClO4 => Cl2O7 + H2O (balance the O and H)

P4O10 => H3PO4

P4O10 => 4 H3PO4 (balance the P)

6 H2O + P4O10 => 4 H3PO4 (balance the O and H)

Now multiply the HClO4 equation by 6

12 HClO4 => 6 Cl2O7 + 6 H2O and add this to

6 H2O + P4O10 => 4 H3PO4 (the H2O cancel out)

–––––––––––––––––––––––––––––––––––––––––––––––

12 HClO4 + P4O10 => 6 Cl2O7 + 4 H3PO4 (balanced)

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"