Energy in Chemical Reactions Lab
by Jeff Bradbury and Patricia Buchanan
Question: Food provides us with energy to live, but how much of this energy can actually be found in a single peanut?
Purpose: To determine the heat of a chemical reaction.
Part 1 Introduction
1. What is a calorie?
A Calorie is a unit of heat. It is the amount of heat needed to raise the temperature of 1 gram of water 1 degree Celsius. You will actually measure the calories of a food product and compare this to the calories on the container. Food Calories usually have an upper case C. 1 Calorie = 1000 calories. Today you will measure calories and then convert them to Calories.
2. How are heat and temperature different?
Temperature is the average amount of kinetic energy contained in the molecules of a substance. It is measured with a thermometer and the units are degrees Celsius. Heat is the total amount of energy in a sample of substance. It is measured indirectly and the units are calories.
3. How is heat measured?
To measure calories in food, for example, the food is burned in a combustion chamber. The heat from the combustion reaction of the food is used to raise the temperature of a sample of water. Knowing the mass of the water and the temperature change of the water the heat gained by the water can be calculated using the following equation:
M X C X ΔT = Heat change in the water (q)
M is the mass of the water. Δ T is the final temperature of the water—the initial temperature of the water (Δ T means change in temperature). C is a constant called specific heat. It tells how a particular substance absorbs heat. All substances absorb heat differently. It takes one calorie of heat to raise the temperature of one gram of water one degree Celsius. C for water is 1 cal/g oC.
125 grams of water are heated by burning a sample of sugar. The temperature of the water goes from 21 oC to 76 oC. How much heat did the water absorb? How much heat did the sugar release?
Answer Absorbed:____________________ Released: ____________________
Safety goggles must be worn at all times. Be careful when lighting a burner.
Part 2 Procedure
Procedure, Observations, and Data:
In this lab you will be working in groups of two.
1. Measure the mass of the apparatus, which is a wire that is attached to a cork
2. Place 1/2 of a peanut on the apparatus and find the mass.
3. Put exactly 25 ml of water in a 100 ml beaker. Measure and record the temperature of the water.
4. Light the peanut on fire with a Bunsen burner, and once the peanut is lit, quickly hold the beaker of water over the peanut. The goal is to get as much heat into the water as possible. (Is it possible to get all of the heat into the water?)
5. Do not let the water boil! Blow out the flame before this happens.
6. After the peanut has burned, make sure the water is mixed so that the hot water is evenly dispersed in the beaker, and measure the temperature of the water and record.
7. Record the mass of the apparatus and peanut after it was burned. Be sure to pick up any crumbs that fell off of the wire.
8. Repeat this experiment until you have burned two peanuts.
Table 1: Mass and Temperature Changes in a Chemical Reaction
|Mass of apparatus||Mass of apparatus and peanut (initial)||Mass of apparatus and peanut (final)||Temperature of water (initial)||Temperature of water (final)||Mass of water used|
Part 3 Calculations (Do this for each peanut)
Show all of the calculations for one nut in your lab book but show the results of all calculations in a table in your book
1. What is the initial mass of the peanut?
2. What is the final mass of the peanut?
3. What is the change in mass of the peanut?
4. What is the change in temperature of the water?
5. What is the heat gain of the water in calories?
6. What is the heat gain of the water in Calories?
7. What is the experimental heat loss of the peanut in Calories?
8. What is the heat loss per gram of the peanut?
9. What is the average heat loss per gram of the peanut?
10. What is the theoretical heat loss per gram of the peanut in Calories? (from the average)
11. What is the efficiency of this experiment? (from the average)
Table 2: Calculating Heat Changes in a Chemical Reaction
|Initial mass of peanut||Final mass of peanut||Change in mass of peanut||Change in temp. of water||Heat gain of water cal.||Heat gain of water Cal.||Experimental heat loss of peanut in Cal.||Experimental heat loss per gram of peanut in Cal.||Ave. heat loss of peanut||Theo. heat loss of peanut||% Eff.|
1. How could you make it so that more of the heat from the burning peanut goes into the water
2. The mass of the peanut went down and the temperature of the water went up. Did you change matter into energy? Make sure you explain your answer with evidence.
3. What happened to the matter of the peanut that was burned?
4. How did the energy get into the peanut in the first place?
Jeff Bradbury is a Professor of Chemistry at Cerritos College in Norwalk; Patricia Buchanan is the Cal Grip Grant Project Assistant at Cerritos College. The original idea for this activity came from the Los Angeles County Office of Education 15 years ago, which the authors modified.
One of the benefits of being a CSTA member is the opportunity to be recommended by CSTA to serve on important state-level committees. One such opportunity is now available. CSTA is seeking science teachers to recommend for service on the Instructional Quality Commission (IQC), formerly the Curriculum Commission. This committee is charged with writing the curriculum frameworks for the Common Core ELA and math standards and will be tasked with developing the framework for the new science standards (once adopted). Members of the Commission serve without compensation, except that they receive their actual and necessary travel expenses in attending Commission meetings and participating in other Commission activities (airfare, lodging, meals, shuttle service, mileage, parking). No funding is provided for substitute teaching or administrative personnel; each applicant employed by a local education agency must obtain the agency’s acknowledgement of the application and the agency’s agreement to absorb any costs for substitute personnel.
CSTA is seeking a member science educator with experience with integrating literacy and math skills into science instruction. A familiarity with the Common Core and Next Generation Science Standards is preferred. If you meet these qualifications and would like to have your name considered, please contact CSTA at email@example.com or 916-979-7004. Please include a copy of your resume and/or a description of your qualifications.
The California State Library invites you to view our online June calendar that highlights four women who have achieved success in STEM-related fields in California. These women and their accomplishments have helped pave the way for future generations.
One such woman is Hattie Scott Peterson, an African American civil engineer who became the first female engineer for the Sacramento district of the Army Corps of Engineers in 1954. She started with the Corps at a time when cultural diversity in the workplace was not common. Her work ethic and personal integrity helped her to overcome the challenges she faced. In the late 1940s she was reputed to be the only female African American civil engineer in the United States.
This monthly calendar is a joint effort of the State Library, California Commission on the Status of Women and Girls, and the California Department of Education.
View the calendar here: http://www.library.ca.gov/calhist/calendar6-1.html?utm_source=csl0613
You Are Invited to Participate in an Online Survey Regarding Possible Changes to the High School Academic Performance Index:
In response to state legislation, the California Department Education (CDE) currently is developing new indicators to include in the high school Academic Performance Index (API).
To help with this important task, the CDE invites administrators, teachers, parents or guardians, students, school board members, educational organizations, community members, and business leaders to take an online survey located on the CDE API Web page at http://www.cde.ca.gov/ta/ac/ap/.
CSTA encourages you to take about 20 minutes to complete the survey and let CDE know the vital role that science takes in preparing students for college and career and how achievement in science should be given a high value in the proposed College and Career Readiness Indicator. The survey closes June 20, 2013 – please act today. Please encourage your colleagues, students, parents of students, and administrators to complete the survey as well.
For more information about revisions to the API, including the proposed College and Career Readiness Indicator, please view the video that was prepared by CDE staff as background material for the survey.
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