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ORLA
Biology
Biomass Calorimeter
Energy from Biomass
Introduction
Have you ever noticed the nutrition label located on the packaging of the food you buy’? One of the first things
listed on the label are the calories per serving. Did you know that the Calorie is the unit used to measure
energy? In this lab you will measure how much energy is contained in various biomass samples.
Background
The law of conservation of energy states that energy cannot be created or destroyed, only converted from
one form to another. This law was used by scientists to derive new laws in the study of heat energy, temperature, and heat transfer. The First Law of Thermodynamics states that the heat energy lost by one body is
gained by another body.
Biomass materials contain stored energy. Burning these materials is a way of measuring their energy content.
In this experiment, you will measure the amount of energy released from a known mass of biomass material
by measuring the change in temperature of a known volume of water.
A homemade calorimeter is used to measure the change in temperature of water caused by the absorption of
the heat released by burning various biomass materials. You will record the change in temperature of the
water, change in mass of the biomass material, and calories and British thermal units produced.
Common units of heat measurement are British Thermal Units (Btu) and calories (cal). A Btu is the standard
unit of energy used to measure the heat content and energy value of fuels. A calorie is the amount of heat
required to raise the temperature of 1 gram (1 milliliter) of water 1 degree Celsius. In other words, it takes one
calorie of energy to raise the temperature of one gram of water by one degree Celsius. Knowing this, the
amount of energy “locked” in a sample of biomass can be calculated if the temperature change is measured.
(note: The normal unit for measuring the energy content in food is called a Calorie (with an uppercase C). A
Calorie is really a kilocalorie, or 1000 calories (lowercase c).)
When biomass bums, its stored energy is quickly converted into heat energy. The heat energy that is
released is then transferred into the water above it in the calorimeter. The temperature change in the water is
then measured and used to calculate the amount of heat energy released from the burning biomass. The heat
energy is calculated using Equation 1
Q = mCΔT
Equation 1
Q = heat energy
m = mass of the water
C = specific heat of the water
ΔT = change in water temperature, Tfinal - Tinitial (Δ is the Greek letter Delta which means “change in”)
Safety Precautions



You must wear safety glasses during this experiment.
DO NOT use flame improperly.
Be careful to let any burnt material cool before touching it or throwing it in the garbage.
ORLA
Biology
Materials
Balance
Graduated cylinder, 50-mL
Ruler, metric
Glass stirring rod
Ethanol
Clay
ring stand with clamp
Biomass samples
watch glass
Thermometer
Butane safety lighter
Pin, large straight
Soda can, empty and clean
water
Procedure
1. Push a pin through the piece of clay so that the pin will be able to hold a piece of biomass and the clay will
sit on the base of the ring stand. (See Figure 1). Note: This setup will now be referred to as the “Biomass
Holder.”***
2. Place a biomass sample on the biomass holder. Measure the combined
mass of the holder and sample. Record your data in the Data Table. Place
biomass holder on the base of the ring stand.
3. Using a graduated cylinder, measure and add 50.0 mL of water to an empty,
clean soda can.
4. Bend the tab on the soda can and slide a glass stirring rod through the hole.
Suspend the can on a support stand using a metal ring. Adjust the height of the
can so that it is about 2.5 cm above the biomass holder.
5. Insert a thermometer into the can. Measure and record the initial temperature
of the water.
6. Rotate the can so it is not directly above the sample. Light the biomass sample.
(It may take time for the sample to begin burning and you don’t want the flame
of the lighter to heat the water in the can.)
Figure 1
7. As soon as the sample begins to burn, place the can over the burning biomass. Allow the water to be
heated until the sample stops burning.
8. As soon as the sample stops burning, record the maximum (final) temperature of the water in the can.
9. Measure and record the final mass of the holder and sample.
10. Remove any biomass residue from the food holder.
11. Repeat steps 1— 10 for a total of 3 vegetative biomass samples and 3 “food” biomass samples.
***You will need to construct an alternative holder for samples that will not stick on the end of the pin. In order to
do this, fold a small aluminum boat from a piece of foil and place your sample in the aluminum boat. Place this
on the base of the ring stand. Don’t forget to lower the aluminum can so it is as close to the burning sample as
when you use the pin holder set up.
12. The combustion of ethanol as fuel
 Record the mass of an empty watch glass.
 Place 15 drops of ethanol (C2H5OH or CH3CH2OH) onto a watch glass and re-mass it.
 Place the watch glass under the tin can calorimeter.
 Light a wooden splint and place it near the ethanol.
 Allow the ethanol to burn and record the temperature changes.
ORLA
Biology
BIOMASS CALORIMETER LAB
Names: ________________, ______________,
________________, ___________________
Data Table
Initial Mass
(sample and
holder)
g
Biomass Sample
Final Mass
(sample and
holder)
g
Change in
mass
Initial Temp.
of Water
0
C
Final
Temp.
of Water
0
C
Δtemp.
Ethanol sample
Analysis and Calculations (you will need to compute some of these on a separate sheet of paper)
1. For each sample burned, determine the change in temperature of the water by subtracting the initial water
temperature from the final water temperature.
2. Calculate the heat gained by the water using Equation 1 from the Background section: Q = m x C x ΔT
. The mass of water used is 50.0 g and the specific heat of water (C) is 1.0 cal/g °C. These values will give
you the heat gained in calories.
Biomass sample 1: 50.0g x 1.0 cal/g °C x change in temp. from your data table = ____ cal.
Biomass Sample 2:
50.0g x 1.0 cal/g °C x change in temp. from your data table = ____ cal.
Biomass Sample 3:
50.0g x 1.0 cal/g °C x change in temp. from your data table = ____ cal.
Biomass sample 4: 50.0g x 1.0 cal/g °C x change in temp. from your data table = ____ cal.
Biomass Sample 5:
50.0g x 1.0 cal/g °C x change in temp. from your data table = ____ cal.
Biomass Sample 6:
50.0g x 1.0 cal/g °C x change in temp. from your data table = ____ cal.
3. Convert the heat gained from calories to food Calories (kilocalories) by dividing the answers above by
1000. Then convert to BTU’s (1 Btu = 252 cal)
Sample 1: ______ cal. ∕ 1000 = ________ Cal.
______ cal/252 = _____ BTU’s
Sample 2: ______ cal. ∕ 1000 = ________ Cal.
______ cal/252 = _____ BTU’s
Sample 3: ______ cal. ∕ 1000 = ________ Cal.
______ cal/252 = _____ BTU’s
Sample 4: ______ cal. ∕ 1000 = ________ Cal.
______ cal/252 = _____ BTU’s
Sample 5: ______ cal. ∕ 1000 = ________ Cal.
______ cal/252 = _____ BTU’s
Sample 6: ______ cal. ∕ 1000 = ________ Cal.
______ cal/252 = _____ BTU’s
ORLA
Biology
4. Determine how much of the biomass burned by subtracting the final mass of the assembly from the initial
mass. (note: you may not be able to complete this calculation if the mass loss from burning was not
measurable)
5. Calculate the energy content per gram of the biomass sample. This is done by dividing the heat gain of
the water (in Calories), by the change in mass of the sample. (see note for #4 above)
Sample 1: ______ cal ∕______ (Δmass) = _______ Energy/gram.
______ BTU/(Δmass) = _____ BTU/gram
Sample 2: ______ cal ∕______ (Δmass) = _______ Energy/gram.
______ BTU/(Δmass) = _____ BTU/gram
Sample 3: ______ cal ∕______ (Δmass) = _______ Energy/gram.
______ BTU/(Δmass) = _____ BTU/gram
Sample 4: ______ cal ∕______ (Δmass) = _______ Energy/gram.
______ BTU/(Δmass) = _____ BTU/gram
Sample 5: ______ cal ∕______ (Δmass) = _______ Energy/gram.
______ BTU/(Δmass) = _____ BTU/gram
Sample 6: ______ cal ∕______ (Δmass) = _______ Energy/gram.
______ BTU/(Δmass) = _____ BTU/gram
6. Review how the amount of energy released differs among the biomass samples. What do you think is an
explanation for these differences?
7. If you were hired to develop a new fuel source for energy, and assuming any of the samples you tested
were viable candidates, which one would you choose? Justify your answer using your experiment results.
8. What are the potential advantages and disadvantages of extracting energy from biomass materials
through combustion?
ORLA
Biology
7. Sam Snackalday wanted to calculate the energy per gram of food from some of his favorite snack foods.
He recorded the data below. Follow the same steps as you did for your own data (#1-5 above) and
calculate the energy content per gram of Sam’s snack food, then rank the food samples from greatest (1)
to least (3) in terms of energy per gram of food.
energy
per g
ranking
Food Sample
Initial Mass
(food and holder)
g
Final Mass
(food and holder)
g
Initial Temp. of
Water
0
C
Final Temperature
of Water
0
C
Cheese puff
4.18 g
4.08 g
21.8 °C
27.1°C
Marshmallow
6.08 g
6.00 g
22.0 °C
23.6 °C
Onion ring
4.87 g
4.74 g
23.0 °C
30.1 °C