Lab 5

Julia (hour 2)

TITLE: INVESTIGATION – Hand Warmer Design Challenge: Where does the heat come from?
PURPOSE: to determine which of the 3 ionic compounds (NaCl, LiCl, or NaCH3COO) is most suitable for use as a hand warmer

PROCEDURE:
DAY 1 (Part 2 only):

1) Measure out 2 separate samples of 100.0 mL of distilled water

2) Heat one to about 50˚C, and place other one in calorimeter (at around 20˚C)

3) Add heater water to calorimeter, cover top, wait 15 seconds, measure temp

4) Repeat

DAY 2:
1) measure 40mL of distilled water into a styrofoam cup on stir plate
2) record temp of water
3) measure out approximately 4g of salt
4) add to water and stir
5)
Julia (hour 2)

3) ∆Hsol

Average:

qsol

qrxn

= (-626 J) + (-515 J) = -571 J

2
= (635 J) + (522 J) = 579 J

2

LiCl

Trial 1:

qsol

= ( m ) ( c ) ( ∆T )

=