Lab Report: Effect of Ethanol Concentration on Oxygen Gas Production

Categories: Chemistry


The objective of this experiment was to investigate the impact of varying concentrations of ethanol on the production of oxygen gas in a reaction involving hydrogen peroxide and catalase. The results indicated a negative correlation, where decreasing the concentration of the 95% ethanol solution led to a reduction in the volume of oxygen gas collected. Various factors, including substrate concentration, temperature, and enzyme concentration, were controlled to ensure the accuracy of the experiment. The findings highlight the importance of substrate concentration in enzyme-catalyzed reactions.


This laboratory experiment aimed to explore the influence of different substrates, specifically ethanol, on reactions mediated by the enzyme catalase. Enzymes, composed of proteins, act as catalysts in biological systems, facilitating chemical reactions by lowering the activation energy required for these reactions to occur.

Enzymes are highly specific to their substrates, meaning they interact with particular reactants to convert them into products. Moreover, enzymes exhibit specific optimal conditions, such as temperature and pH levels, under which they function most effectively.

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Catalase, a common enzyme found in various organisms exposed to oxygen, serves as a catalyst in the decomposition of hydrogen peroxide (H2O2) into water (H2O) and oxygen gas (O2). This reaction occurs as follows:

2H2O2 → 2H2O + O2

Catalase demonstrates exceptional efficiency in this process, with a single molecule of catalase capable of converting 40 million molecules of hydrogen peroxide into water and oxygen gas each second.

Ethanol, an alcohol, has been shown to have detrimental effects on functional liver tissue. Excessive consumption of ethanol can lead to liver damage, including inflammation and scarring, due to the production of toxins and reactive oxygen species (ROS).

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However, it is important to note that the chicken liver used in this experiment is non-functional and cannot metabolize ethanol. Ethanol metabolism involves multiple enzymatic processes within liver cells, which require a living organism to activate these enzymes. Since the chicken liver is not viable, it lacks the enzymatic activity necessary for ethanol metabolism, making it non-functional in this context.

Materials and Methods

The following materials and equipment were used in the experiment:

  • 6g of chicken liver
  • 6mL of distilled water
  • 50mL gas collection tube
  • Retort stand with a burette clamp
  • Rubber tube
  • Test tube with a side arm
  • J-tube
  • 5mL of 95% ethanol
  • 3mL of 3% hydrogen peroxide
  • Weighing scale
  • Syringe

The experimental procedure was as follows:

  1. Crush 6g of chicken liver in a mortar and pestle and mix it with 6mL of distilled water.
  2. Clamp a 50mL gas collection tube onto a retort stand using a burette clamp, positioning it over a 1000mL beaker filled with water.
  3. Attach a rubber tube to a test tube with a side arm, with a J-tube pointing into the gas collection tube.
  4. Measure 5mL of 95% ethanol using a syringe and pour it into the test tube with a side arm.
  5. Weigh 1g of the crushed chicken liver and add it to the test tube with ethanol.
  6. Pour 3mL of 3% hydrogen peroxide into the test tube with a side arm and immediately cap it with a rubber stopper.
  7. Observe and record the volume of oxygen gas produced.
  8. Repeat the above steps while diluting the 5mL of 95% ethanol solution with 10mL of distilled water to create a new concentration of 32% ethanol.

The ethanol dilution was calculated using the formula C1V1 = C2V2, where C1 is the initial ethanol concentration (95%), V1 is the initial volume (5mL), C2 is the new ethanol concentration, and V2 is the total volume (5mL + 10mL = 15mL).

Using this formula, the new concentration was determined to be 31.67% ethanol.


After conducting six trials, the results consistently demonstrated a negative correlation. As the concentration of ethanol in the solution decreased due to dilution with distilled water, the volume of oxygen gas collected also decreased. This relationship is depicted in Figure 1 below.

Ethanol Concentration (%) Volume of Oxygen Gas (mL)
95% 10 mL
32% 8 mL
21% 6 mL
16% 4 mL
13% 3 mL
10% 2 mL


Several factors influenced the outcome of this experiment, with substrate concentration being a key variable. Substrate concentration refers to the number of substrate molecules in a solution, while enzyme concentration represents the number of enzymes available. In enzyme-substrate reactions, one enzyme can only interact with one substrate molecule at a time, leading to a direct relationship between enzyme and substrate concentration. An increase in either enzyme or substrate concentration results in a higher frequency of collisions between molecules, enhancing reaction rates.

Control groups were implemented in the experiment to maintain consistent conditions. Temperature control was crucial, as temperature influences the movement of molecules within a solution. Higher temperatures lead to increased molecular motion and collision rates, but excessive heat can denature enzymes, rendering them non-functional. Therefore, maintaining a constant temperature was essential to ensure reliable results.

Another control variable was the mass of chicken liver used in each trial. The chicken liver contains catalase, and altering its mass could impact the enzyme concentration in the reaction. A higher mass of chicken liver would result in increased enzyme concentration, potentially leading to more reactions.

Several challenges were encountered during the experiment, including the rapid addition of hydrogen peroxide into the test tube and difficulties in sealing the test tube promptly. These issues led to the escape of some oxygen gas instead of channeling it through the rubber tube into the gas collection tube. Additionally, when measuring 1g of chicken liver on a scale and transferring it to the test tube, some chicken liver particles adhered to the plastic container or the test tube's sides. This hindered complete interaction between the chicken liver and catalase enzyme, potentially affecting the results.

Notably, the presence of ethanol in the experiment played a crucial role. Ethanol is an alcohol that must be metabolized by the liver, and its breakdown generates toxic by-products, such as acetaldehyde, which can harm the liver. However, the chicken liver used in this experiment was non-functional, lacking the necessary enzymatic activity to metabolize ethanol. Consequently, ethanol's dilution with distilled water primarily affected the concentration of hydrogen peroxide in the reaction, leading to a decrease in its concentration.

Furthermore, the experiment considered the influence of temperature on enzyme activity. Ectothermic organisms, which cannot regulate their body temperature, experience variations in enzyme activity with changing environmental temperatures. For instance, reptiles rely on external sources of heat, such as sunlight, to maintain their body temperature within a specific range. This adaptation ensures that enzymes function optimally within the temperature range experienced by the organism, preventing denaturation due to extreme temperature shifts.


The experiment aimed to investigate the impact of decreasing the concentration of a 95% ethanol solution on the production of oxygen gas in a reaction involving hydrogen peroxide and catalase. The results consistently demonstrated a negative correlation, indicating that as the ethanol concentration decreased, the volume of oxygen gas collected also decreased. This finding aligns with the hypothesis that a reduction in ethanol concentration would lead to reduced oxygen gas production.

It is important to acknowledge that the non-functional chicken liver used in the experiment limited the effects of ethanol to its dilution of hydrogen peroxide, as the liver lacked the enzymatic activity required for ethanol metabolism. Despite the experimental challenges, the results underscore the significance of substrate concentration in enzyme-catalyzed reactions.


Based on the observations and outcomes of this experiment, the following recommendations are proposed for future research:

  1. Improved Sealing Techniques: Enhance the sealing of the test tube to prevent the escape of oxygen gas during the reaction.
  2. Minimize Particle Adherence: Take measures to minimize the adhesion of chicken liver particles to containers and test tube surfaces to ensure complete reaction.
  3. Consider Live Liver Samples: Future experiments could explore the use of live liver samples to examine the full impact of ethanol on liver function and enzyme activity.
  4. Explore Other Substrates: Investigate the effects of various substrates on enzyme-catalyzed reactions to gain a comprehensive understanding of substrate specificity.

Implementing these recommendations can enhance the accuracy and reliability of future experiments examining the interactions between enzymes, substrates, and environmental factors.

Updated: Dec 29, 2023
Cite this page

Lab Report: Effect of Ethanol Concentration on Oxygen Gas Production. (2016, May 23). Retrieved from

Lab Report: Effect of Ethanol Concentration on Oxygen Gas Production essay
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