# chemistry

posted by .

NH4NO3(s) + H2O(l) NH4NO3(aq) ΔH = +25.7 kJ
What is the final temperature in a squeezed cold pack that contains 40.0 g of NH4NO3 dissolved in 125 mL of water? Assume a specific heat of 4.18 J/(g·°C) for the solution, an initial temperature of 25.0°C, and no heat transfer between the cold pack and the environment.
For this question im suppose to use the q=mc delta T ?

• chemistry -

That 25.7 kJ usually is quoted as 235.7 kJ/mol which means 25.7 kJ/80g.
Therefore, heat absorbed by the NH4NO3 will be 25,700 J x (40/80) = about 13,000 J
Then -13000J = 125 x 4.184 x (Tf-Ti)
Tf = unknown
Ti = 25C
Tf is something like 0.5C but that's an estimate.

## Similar Questions

1. ### college chemistry-thermochemistry

A 1.50g sample of NH4NO3(s) is added to 35.0g of water in a foam cup and stirred intil it dissolves. The temperature of the solution drops from 22.7 to 19.4 degrees celcius. What is the heat of dissolution of NH4NO3, expressed in kJ/mol …
2. ### Chemistry

The standard heat of formation of solid ammonium nitrate. NH4NO3 is -330kJ/mol. The equation that represents this process is: a) N2(g)+ 4H2(g)+3O2(g)->NH4NO3+ 330kJ b) 2N(g)+ 4H(g)+ 3O(g)-> NH4NO3+ 330kJ c) NH4(g)+ NO3(g)-> …
3. ### Chemistry

Instant cold packs used to treat athletic injuries contain solid NH4NO3 and a pouch of water. When the pack is squeezed, the pouch breaks and the solid dissolves, lowering the temperature because of the following endothermic reaction. …
4. ### chemistry

When a 3.90-g sample of solid ammonium nitrate dissolves in 60.0 g of water in a coffee-cup calorimeter, the temperature drops from 24.5°C to 19.3°C. Calculate DH (in kJ/mol NH4NO3) for the solution process NH4NO3(s) ---> NH4+(aq) …
5. ### chem

(a) When a 4.75-g sample of solid ammonium nitrate dissolves in 60.0 g of water in a coffee-cup calorimeter (see figure), the temperature drops from 23.0‹C to 16.6‹C. Calculate ƒ¢H (in kJ/mol NH4NO3) for the solution process …
6. ### chemistry

NH4NO3(s) NH4+(aq) + NO3−(aq) In order to measure the enthalpy change for this reaction above, 1.07 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8°C and the final temperature …
7. ### CHM1045

NH4NO3(s) right arrow NH4+(aq) + NO3−(aq) In order to measure the enthalpy change for this reaction, 1.21 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8°C and the final …
8. ### Chemistry

In a coffee cup calorimeter, 1.60 g of NH4NO3 is mixed with 75.0 g water at an initial temperature of 23.50 ºC. When the salt was completely dissolved, the solution temperature of the calorimeter became 21.80 ºC. Assume the solution’s …
9. ### chemistry urgent

NH4NO3(s)+H2O(l)→NH4NO3(aq) ΔH = +25.7 kJ. What is the final temperature in a squeezed cold pack that contains 45.5g of NH4NO3 dissolved in 125 mL of water?