• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

An experiment to investigate the change in cell potential with concentration.

Extracts from this document...


8/1/04 Emma Duckworth 7E An experiment to investigate the change in cell potential with concentration. Aim: The purpose of this experiment was to investigate how changing the silver ion concentration in a silver half cell affects the potential of the silver electrode. Apparatus: ==> Chemicals/ substances: * Copper (II) sulphate solution * Copper foil * Silver nitrate solution (make up to 6 different concentrations) * Silver wire * Distilled water * Saturated potassium nitrate solution ==> Additional apparatus: * Safety goggles * 7 beakers * 6 pieces of filter paper * High resistance voltmeter * 2 connecting leads with crocodile clips Diagram: Method: ==> Set up the following cell, using 1 M copper (II) sulphate solution and 0.1 M silver nitrate solution, including a voltmeter and a salt bridge: Cu(s) Cu 2+ ((aq), 1M) Ag+ ((aq), x M) Ag(s) ==> Measure the potential difference of the cell with the voltmeter and note its polarity. Remove the salt bridge as soon as possible. ==> Dilute the 0.1 M silver nitrate solution to 0.01 M silver nitrate solution, renew the salt bridge and then measure the potential difference of the cell with this concentration (0.01 M) of silver nitrate solution in the silver half cell. ==> Repeat this for each of the listed concentrations (0.1 M, 0.01 M, 0.001M, 0.0001 M, 0.003 M, 0.00033 M) ...read more.


(2) The slope on my graph corresponds to the gradient of my line (I drew a line of best fit). Gradient is ?y / ?x = 0.62 -0.52 / -1 - (-3) = 0.09 / 2 = 0. 045 V. In the Nernst equation, the equation that shows the relationship between the potential, E, of a half cell and the standard electrode potential: E = E? + 0.059 V/ z log (Ag+), this gradient corresponds to 0.059 V / z as the Nernst equation fits the general equation for a line y = mx + c. Here, y = E?, x = log (Ag+) and so the gradient must be 0.059 V/ z. ????! Conclusion: From my results and graph the following conclusions can be drawn: ==> When the electrode potential of a cell is not measured under standard conditions and the concentration of the ions in a half cell is not the standard 0.1 M, the electrode potential of the half cell and the potential difference of the whole cell is altered. ==> As ions in a half cell become more concentrated the electrode potential of that half cell and the cell potential both become more positive. ==> When the electrode potential of a half cell is graphed against the log of the concentration of ions in that half cell an increasing straight line is produced showing that the ...read more.


The slope of this graph corresponds to part of the Nernst equation, an equation that links together the cell potential, electrode potential and concentration of ions and so allows for the fact that concentration of ions effects the electrode potential and cell potential.. The equation is: E = E? + 0.059 V/ z log (conc. oxidised/ conc. reduced) (z is the number of electrons transferred when the oxidised species changes into the reduced species - in our case the value is 2 as 2 electrons are transferred.) This means that the electrode potential increases as the concentration of the ions increased by a certain relationship. My results seem to form a sensible pattern so I would assume they are reasonably accurate, but if I were to do this experiment again I would perhaps change the voltmeter and, to investigate the Nernst equation further I could perhaps measure the silver standard electrode potential using a standard hydrogen electrode. (although this may not make any difference) or investigate the effect of pH by changing the pH of solutions in a electrochemical cell that involve hydrogen or hydroxide ions (such as potassium permanganate) . It was very important in this experiment that we kept it a fair test by only changing the concentration of one of the solutions in the cell so that we had the copper cell as a reference point that we could use to calculate the silver electrode potential. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Cell Biology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related University Degree Cell Biology essays

  1. The purpose of this investigation is to discover whether different respiratory substrates will affect ...

    I will place the delivery tube into the opening of the burette, which will be connected to the conical flask. 6. In my plan I was originally going to use a boiling tube for the yeast/substrate reaction. However I have found out that this reduces the surface area of the

  2. An experiment measuring the potential difference generated by various simple electrochemical cells.

    (See diagram). Make sure the 2 electrodes are connected to the correct terminal of the voltmeter - the more reactive/ better reducing agent at the negative terminal (on the left) and the less reactive/ better oxidising agent at the positive terminal (on the right).

  1. IMMUNOLOGY PRACTICAL: Differential Blood Cell Counts

    Neutrophils increase in response to bacterial infection. They destroy bacteria by enveloping and digesting them, a process called phagocytosis. When many neutrophils are needed, they are released from the bone marrow as immature cells, called bands or stab cells. On a stained blood smear, the cytoplasm of neutrophils has numerous

  2. Investigation to determine the water potential of potato cells.

    be 0.8 and 1 Mole respectively and preliminary experiments show that this far exceeds the isotonic point for potatoes. Predicted Graph Explanation of prediction. Osmosis is the net movement of water molecules from an area of high water potential to a region of lower water potential across a partially permeable membrane.

  1. Investigation into the integrity of cell membranes under different conditions

    the membrane to become more rigid allowing less movement, in relation to the beet root this allowed less molecules to pass through.

  2. Discuss the role of CaMKII (calcium/calmodulin-dependent kinase II) autophosphorylation in learning and memory

    NMDA receptor subunits contain 3 membrane spanning regions and a C-terminal tail of various lengths, which produces the intracellular portion of the receptor (Strack et al, 1998). NMDA receptors are heteromeric complexes consisting of NR1, NR2 subunits and less commonly NR3 subunits.

  1. This experiment was carried out to characterize an enzyme, -amylase by extracting it from ...

    �g Blank 0.000 0.000 0.000 0.00 standard BSA 0.277 0.280 0.279 150.00 ?-amylase extract 0.044 0.044 0.044 231.60 Figure 1: The graph of absorbance at 560nm against the mass of protein in solutions, �g Table 2: The absorbance and mass of protein in standard BSA and ?-amylase after 1st dialysis

  2. POMC cell function

    The skin expression of the CRH or POMC systems is stimulated by ultraviolet radiation (UVR). It also stimulates the expression of the corresponding receptors (Slominski, Wortsman, Luger, Paus, & Solomon, July 2000, PP. 979-1020 ). The POMC gene engenders the encoding of a polypeptide hormone precursor.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work