Fruit cell emf varying with temperature

In summary, the experiment aimed to investigate the relationship between the temperature and voltage of a fruit cell. The initial voltage of the orange juice was around 0.2mV and decreased as the juice was heated. However, fluctuations in voltage were observed when bubbles formed around the copper electrodes. The possible theories for this behavior include the increase in resistance due to higher temperature and the potential electrochemical reactions or changes in conductivity. The exact cause of the voltage fluctuations is still unclear.
  • #1
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Homework Statement


Hi all,
In school, I tried to investigate how the emf (voltage) of a fruit cell varies with temperature. I took ~200ml of freshly squeezed orange juice, 2 copper electrodes, a voltmeter, heater and thermometer.

I set up everything, and got an initial voltage of somewhere around ~0.2mV or so IIRC.
I started heating the orange juice, and the voltage went down. It seemed to be going down and down, until some bubbles around the copper electrode started to rise to the surface, when fluctuations in the voltage were noticed, sometimes up to 30mV.


Homework Equations


What is the relationship between the temperature and the voltage of a cell? I was thinking that the voltage (or perhaps current?) should rise, since the molecules are moving faster. On the other hand, the higher the temperature, the higher the resistance, and so in turn there should be a lower current?

All in all, should the voltage be affected by the change in temperature at all?


The Attempt at a Solution


I am lost. As proposed above, I have found 2 possible theories, but I cannot make sense of why the voltage would jump about.

Thanks in advance.
 
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  • #2
Increasing the temperature would increase the resistance in the copper electrodes.

A sudden onset of an increase in voltage could indicate the initiation of some electrochemical reaction, the sudden increase in conductivity of the solution, or the breakdown of any protective oxide on the electrode.
 
  • #3


Dear student,

Thank you for sharing your findings on the relationship between temperature and voltage in fruit cells. This is an interesting topic and it is great that you are exploring it.

From your experiment, it seems that the voltage of the fruit cell decreases as the temperature increases, until it reaches a certain point where it starts fluctuating. This is a common phenomenon in electrochemical reactions, where the rate of the reaction increases with temperature, leading to a decrease in voltage.

The reason for the fluctuations in voltage could be due to the release of gases such as oxygen and carbon dioxide during the reaction. These gases can create a barrier between the electrodes and the fruit juice, leading to a decrease in conductivity and therefore a decrease in voltage. However, as the gases are released and the barrier is removed, the voltage can increase again, leading to the observed fluctuations.

In general, the voltage of a cell is affected by both temperature and resistance. As you correctly pointed out, with an increase in temperature, the molecules in the fruit juice will move faster, leading to an increase in conductivity and therefore an increase in voltage. However, as the temperature increases, the resistance of the solution also increases, leading to a decrease in voltage. The net effect of these two factors will determine the overall change in voltage with temperature.

I would suggest conducting more experiments with different temperatures and different types of fruit cells to further explore this relationship. It would also be helpful to measure the resistance of the solution at different temperatures to better understand the fluctuations in voltage.

Keep up the great work in your scientific investigations!

Best regards,
 

What is a fruit cell EMF?

A fruit cell EMF (electromotive force) is the measure of the electrical potential difference between the inside and outside of a fruit cell. It is a result of the concentration of charged ions inside the cell membrane and can be affected by various factors, including temperature.

How does temperature affect fruit cell EMF?

Temperature can impact the movement of charged ions within a fruit cell, which can affect the overall EMF. Higher temperatures can increase the movement of ions and therefore increase the EMF, while lower temperatures can decrease the movement of ions and decrease the EMF.

What is the relationship between temperature and fruit cell EMF?

The relationship between temperature and fruit cell EMF is directly proportional. This means that as temperature increases, so does the EMF, and as temperature decreases, the EMF also decreases.

Why is it important to study the variation of fruit cell EMF with temperature?

The variation of fruit cell EMF with temperature can give insight into the overall health and functioning of fruit cells. It can also help scientists understand the mechanisms of ion movement within cells and how temperature can affect cellular processes.

What are some potential applications of studying fruit cell EMF variation with temperature?

Studying fruit cell EMF variation with temperature can have various applications, including understanding the ripening process of fruits and vegetables, improving storage and transportation methods for produce, and developing new technologies for monitoring and controlling cellular processes.

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