Question

We can also use the equation for enthalpy change for physical phase changes. Consider the phase change H2O(l) → H2O(g). Calculate ΔHrxn.

Use ΔHf values from the table above.

ΔHrxn =

A) -527.6 kJ
B) 44.0 kJ
C) 527.6
D) -44.0

Answer 1

@touseii45
@thomaster

Answer 2

where is the table?

Answer 3

right here

Answer 4

or this

All the coefficients are 1.

ΔHrxn = (sum of ΔHf products - sum of ΔHf reactants)

ΔHrxn = [(1)(-1206.9 kJ/mole) + (1)(-241.8 kJ/mole)] - [(1)(-986.09 kJ/mole) + (1)(-393.6 kJ/mole)]

We must be very careful in our math to properly handle all the negative signs.

ΔHrxn = [-1206.9 + (-241.8)] - [-986.09 + (-393.6)] kJ

ΔHrxn = [-1206.9 - 241.8] - [-986.09 - 393.6] kJ

ΔHrxn = (-1448.7) - (-1379.69) kJ

ΔHrxn = -1448.7 + 1379.69 kJ

ΔHrxn = - 69.0 kJ

This reaction is exothermic.

Answer 5

uhm okay wow i understood none of that, @electrokid can you help?

Answer 6

or @thomaster can you help? your a genius...

Answer 7

i have no idea. here, help with this instead

http://openstudy.com/study#/updates/51658bfde4b066fca66102c3

Answer 8

Hint: remember that this will jsut be your Latent hear of vaporization ...

Answer 9

just a phase change.. no change in temperature.

Answer 10

\[285.8-241.8\]

Answer 11

http://openstudy.com/study#/updates/51659543e4b0902dbc1d05b2

i really need help here