Food Combustion Lab

Introduction

How Much Heat is Released Upon Fuel Combustion?

The purpose of this lab is to measure the amount of heat released during combustion of some common liquid fuels and food items. You will learn and have to calculated the heat of combustion (Delta H of Combustion) for each fuel. You need to use good experimental measurmentes and look at your ability to reproduce you experimental results.

Instructions

General Procedure

Step 1.

 Assemble a calorimeter as demonstrated in the pre-lab introduction. Include a diagram of the apparatus in your lab notebook.

Step 2.

 Working in pairs, you will use a small burner to combust the fuels; practice lighting and extinguishing the burner.

Step 3.

 For each combustion experiment, three experimental parameters required: 
 

 a) the mass of fuel combusted, 

 b) the mass of water heated as a result of combustion, and 

 c) the change in temperature of the water. 

(All masses are to be measured and recorded to ± 0.01 g; initial and final temperatures are to be measured and recorded to ± 0.1C. The following are some suggestions to obtain the experimental parameters.)

Mass of fuel: It is suggested that the burner be massed (weighed) with the cap on at the beginning of an experiment and then again at the end of the experiment.

Mass of the water: The mass of the water used during the experiment is best determined by first measuring the volume in a graduated cylinder (~50 mL) and then determining the exact mass by taring the “soda can” on the balance and then adding the water.

Temperature change: We will use the Vernier stainless steel temperature probes to measure an initial temperature (Ti) and a final temperature (Tf), then do the math. We suggest holding the thermometer at all times for three reasons: a) if you sit the thermometer on the very bottom of the can, it may be much hotter than the water itself, b) by holding the thermometer, you can gently agitate the water to allow the heat to dissipate throughout the entire water sample, and c) you are much less likely to “tip over” the apparatus.

Step 4.

 To initiate the experiment, obtain the mass of the burner with cap, and then do the following quickly: a) remove the burner cap, b) light the burner, c) place the water-filled soda can/temperature shield on top of the burner. Monitor the temperature while the fuel combusts, extinguishing the flame once the temperature has risen ~ 20 C. Measure and record the final temperature of the water.