HEAT: SPECIFIC AND LATENT HEAT OF VAPORIZATION
INTRODUCTION
The purpose of this lab is to determine the specific heat of metal samples and the latent
heat of vaporization of water.
EQUIPMENT LIST
Hot plate (Other heat source)
Metal samples (At least two different metals)
Styrofoam cups (At least 8 oz. Cup)
Thermometers (Digital thermometers preferred)
(Celsius, 0.1 degree accuracy preferred for Specific heat)
(Celsius, 1 degree accuracy preferred for Latent heat)
Immersion coffee heater
Graduated Cylinder
String and pencil
Metal container to heat metal samples
Timing device with 1 second accuracy
OBJECTIVES
Determination of specific heat
Determination of Latent heat of vaporization
Understand the principle of density of water
NEEDED EQUATIONS
Q′ = rate of heating
Mw = mass of water
Cw = specific heat of water
ΔT/Δt = slope of graph, rate of temperature change
Δm = mass of water
Δt = time which vaporation occurred
EXAMPLE CALCULATIONS
Specific Heat
Mw Cw (Tf – Tiw) = Mm Cm(Tim – Tf)
Latent Heat
Q′ = ΔQ/Δt = Mw Cw ΔT/Δt
Q′ Δt1 = Δm Lv
DETAILED PROCEDURE
Specific Heat
1.
Determine the mass of the metal samples in kg.
2.
Using metal can, place the metal samples in the can. Fill the can with
water.
3.
The samples should have strings tied to them and connect to a pencil. The
string should suspend the sample.
4.
Place the can on a hot plate and heat to boiling. Let boil for five minutes to
allow for equilibrium.
5.
Measure a sufficient amount of water using a graduated cylinder to allow
for full immersion of the metal sample. (Approximately 75-150 ml)
6.
Pour the water into the Styrofoam cup. Measure the temperature of the
water in the cup. Measure the temperature of the water in the can.
7.
Remove the metal sample from the can and place into the Styrofoam cup.
(Do this quickly)
8.
Stir the water constantly with the thermometer and record the highest
temperature.
Latent Heat
1.
Place approximately 200 ml of water in a Styrofoam cup.
2.
Place immersion coffee heater in the cup, making sure it does not touch the
cup.
3.
Measure the initial temperature of the water and plug in the heater.
4.
Use a thermometer to constantly stir the water and take temperature
readings every 10 seconds. Note the time in which boiling occurs.
Continue at least 2 minutes after boiling begins.
SAMPLE DATA
Mw = 75ml = 75o
Mm = 50g
Cw = 1 cal/goC
Tim = 100oC
Tiw = 22oC
Tf = 27oC
Mw Cw (Tf – Tiw) = Mm Cm (Tim - Tf)
(75g) (1cal/goC) (27oC - 22oC) = (50g) Cm (100oC - 27oC)
375 cal = (3650goC) Cm
375cal/3650goC = Cm
.103 cal/goC = Cm
Mw = 200g = 200ml
Cw = 1 cal/goC
ΔT/Δt = 1oC/sec
Δm = 40g
Δt1 = 120 sec
Q′ = Mw Cw ΔT/Δt
Q′ = (200g) (1cal/goC) (1oC/sec)
Q′ = 200 cal/sec
Q′ Δt1 = Δm Lf
(200 cal/sec) (120 sec) = (40g) Lf
600 cal/g = Lf
RECOMMENDED SOFTWARE PACKAGES TO USE
MS Word
Excel