can you help me

[ManBearPig]

hey, i'm trying to figure out how to do this.

i know i have to use (m)(c)(Tfinal-Tinitial), but i've got no idea how.

it asks how much salt is used if you use 500ml of water, and the target temp is 2C, and the room temp (or initial temp i think) is 22C.

it's really pissing me off, i've got no idea how to do this, but i feel like i'm almost there. any ideas? thanks alot

 

[SagaLore]

:wine:

 

[newb111]

:beer:

 

[ManBearPig]

this is the biggest pain in the butt...every week we have to write a 7+ page report, and even when i try to get it done early (like now), i still cant figure out what i'm doing so it takes longer lol

 

[allies]

Wait... can you write the question? I mean... what are you looking for?

 

[ManBearPig]

Originally posted by: allies
Wait... can you write the question? I mean... what are you looking for?

it's about hot packs and cold packs, so with that said, heres what it says:

for each salt to be used for the cold pack, calculate how much salt is required to prepare a pack containing 500mL of water with a target temperature of 2C (assume room temp. is 22C).

then it asks a similar question for a hot pack

the salts i am considering are (with their Hsoln):

NH4NO3 23.7
NaC2H3O2 -13.72

so i assume that i would use NH4NO3

 

[allies]

So basically we need to find the specific heat of the solution? Lets see our knowns... we know our deltaHsoln and our deltaT. So we need specific heat and mass of total solution.

Known:

deltaHsoln
deltaT
Mass H2O
Volume H2O


Unknown:

Mass solute
Specific heat of solution


With some work I think you can figure it out.

 

[heinz256]

i think u gotta use stoich