Designing a Hand Warmer
Purpose: To determine the best solute to use to make a safe hand warmer.
Procedure:
Data
Part A: (table)
Part B and C: (table)
Calculations:
Part A:
#13- calculate calorimeter constant
Part B and C: #7 Calculate the molar heat of solution
q solution = -(qaq + qcal)
= -(m s ΔT + Ccal Δ T)
ΔH solution = ___J x 1KJ __ x ____ g =
g
1000J
1 mol
_____KJ/ mol
Where the first ___J is the qsolution
Discussion/ Questions
1a. What data is needed to calculate the enthalpy change?
Mass, Tinitial, Tfinal
1b. Identify variables that will influence the experimental data.
Insulation ability of container, volume of water, whether the solute all dissolves
1c. Which variable should be controlled (kept constant).
Volume of solvent, continuous stirring, same container
1d. What is the independent (changed) variable? type of solute
What is the dependent variable (depends on changes) Temperature
1e. Which factors affect the precision of your results?
Precision of balance, precision of graduated cylinder, precision of thermometer,
Insulation ability of calorimeter.