Question

Tables 3 & 4
	Cold Pack	Hand Warmer
Volume	20mL	20.6mL
Time (sec)	Temperature (°C)	Temperature (°C)
Initial	22.6 C	25.8 C
30	12.7 C	33.7 C
60	11.2 C	39.0 C
90	9.8 C	46.9 C
120	9.3 C	51.3 C
150	6.4 C	55.6 C
180	5.6 C	59.2 C
210	6.1 C	61.3 C
240	5.8 C	62.2 C
270	6.2 C	63.0 C
300	6.9 C	64.5 C
330	7.8 C	65.2 C
360	8.3 C	61.3 C
390	8.8 C	60.6 C
420	9.9 C	58.4 C
450	10.6 C	57.3 C

Calculate the enthalpy of the reaction for each trial using the minimum/maximum temperature reading for ΔT. Show work below.

Answer 1

Solution :-

#1) Calculation for the cold pack

Volume = 20 ml

Assume that the specific heat and density is same as water

Therefore we have

20 ml * 1.0 g /ml = 20 g

Now using this we can find the delta H for the cold pack

Initial temperature = 22.6 C

Final temperature = 5.6 C

q= m*s*delta T

= 20.0 g * 4.184 J per g C * (5.6 C – 22.6 C)

= -1423 J

Therefore the delta H for the cold pack is -1423 J

#2) Now lets calculate for the hot pack ( hand warmer)

Initial temperature = 25.8 C

Final temperature = 65.2 C

Mass of solution = 20.6 ml * 1.0 g /ml = 20.6 g

q= m*s*delta T

= 20.6 g* 4.184 J per g C * (65.2 C -25.8 C)

= 3396 J

Therefore the delta H for the hand warmer is 3396 J