Chemistry, Calorimetry finding delta H

[alexpratt]

Homework Statement

Sodium metal reacts with water to produce hydrogen gas and sodium hydroxide
according to the equation:
2 Na(s) + 2 H2O(l) ? 2 NaOH(aq) + H2(g)
When 0.030 mol of Na is added to water, the temperature of the calorimeter rises
from 25.00C to 37.90C. If the heat capacity of the calorimeter is 400 J/C,
calculate ?H for the reaction as written

Homework Equations

q_system=-q_surroundings
q=CdeltaT
q=ndeltaH (?)

The Attempt at a Solution

i haven't actually tried to work out the numbers because I am not given the answer and i won't know if I am right or wrong. I have some ideas though which I would like someone to validate for me!

i know i can find q for the calorimeter because I am give C for the calorimeter and the temperature change. And that q of the calorimeter is -q for everything else.
So, once i have q, would i plug that into q=ndeltaH solve that for deltaH and use .03 moles for the n value?

this is the only kind of calorimetry problem i have trouble with constantly, on top of that my final exam is in two hours :( shouldn't leave things til the last minute i suppose.

anyways, any help at all is appreciated! like i said, i don't expect you to do the problem for me, i was just wondering if i could be pointed in the right direction!

 

[Borek]

2 Na(s) + 2 H2O(l) ? 2 NaOH(aq) + H2(g)

So, once i have q, would i plug that into q=ndeltaH solve that for deltaH and use .03 moles for the n value?

That would give you delta H per one mole of Na, the way reaction is written heat that evolves would be twice that (two moles of Na reacting).

 

[alexpratt]

ok, that makes sense thank you!

i had some other examples that i had the answer to and i noticed some of my answers were half of the right answer but i never made that connection. Unfortunately that question was on the exam :(

regardless thank you for your help, it'll come in handy next semester I am sure!