Fermentation Lab
Purpose: To observe the process of fermentation in a living organism, yeast (Saccharomyces).
Materials (per student):
125 ml Erlenmeyer Flask (4) Yeast (Saccharomyces) Hot Plate or Microwave
12 inch Balloon (4) Balance Piece of String
Apple Juice Sugar Ruler
Calculator Funnel Pencil/Pen/or Marker
Procedure:
Day 1
1) Gather the needed materials. Label the 125ml Erlenmeyer flasks 1, 2, 3, and 4. Put your groups name on each to identify your own flasks.
2) Pre-stretch the balloons. Do this by stretching them and blowing them up and letting out the air.
3) Set up the following flasks using the procedure for each flask. Make sure to be accurate in your measurements.
Flask #1: 75 ml of warm water
6.5 grams of sugar
Put the pre-stretched balloon immediately over the top of the flask
Flask #2: 75 ml of warm water
1 gram of yeast
Put the pre-stretched balloon immediately over the top of the flask
Flask #3: 75 ml of warm water
6.5 grams of sugar
1 gram of yeast
Put the pre-stretched balloon immediately over the top of the flask
Flask #4: 75 ml of apple juice
1 gram of yeast
Put the pre-stretched balloon immediately over the top of the flask
4) Gently stir the flask to mix the materials in each flask. Allow the flasks to sit for 24 hours.
Day 2
5) Use a piece of string to measure the circumference of each balloon. If the balloon does not look noticeably different from the start of the experiment, calculate the circumference of the balloon as zero.
Fill out the data table.
6) Use the circumference of the balloon and the following equations to calculate the diameter of the balloon. Fill out the data table C = 2pr d = 2r
7) Calculate the volume of gas produced using the following equation. Fill out the data table.
Volume of Gas Produced = 4.187 x (diameter of balloon in cm / 2)3
8) Clean up your lab supplies. Make sure to clean out all flasks thoroughly.
Data/Results:
Flask # / Contents / Circumference of Balloon (cm) / Diameter of Balloon (cm) / Volume of Gas Produced (cm3)** round all answers to 2 decimal places
Discussion:
1) What process was observed in this lab?
2) What gas was produced in this process? What observation was seen to show this production?
3) What is the overall equation of cellular respiration? Circle the reactants, Place a box around the products.
4) Which flask or flasks had no observable gas production? Why is this so?
5) Which flask produced the largest volume of gas? Why might this be so?
6) What are some observable indicators that a chemical reaction was taking place inside some of the flasks? (Name two)
7) How are photosynthesis and cellular respiration connected in a biochemical pathway?