Soaked Paper Essay, Research Paper
This
experiment aims to investigate the resistance of brine soaked paper when an
electrical current is passed through it. Planning: ?Previous experiments have taught me that the
electrical resistance will rely on several key variables.? These include the length of paper, its
thickness but most importantly the number of sodium and chlorine ions carrying
the charge.? Knowing this, I have
decided to investigate the concentration of brine in this experiment.? To provide an accurate prediction, I must
research into the scientific details in this experiment and recall information
from previous investigations.? This will
give me a greater understanding of the experiment?s implications and likely
results.Ionic
compounds do not have a molecular structure, but form a three-dimensional array
of ions called a crystal lattice.? In a
crystal of sodium chloride, the ions are arranged so that each Na+ ion is
surrounded by six Cl- ions and
vice versa.? Because the ions are held
rigidly in place by the electrostatic attractions between any one ion and the
oppositely charged ion surrounding it, these compounds tend to be very
brittle.? They do not conduct electricity
when in a solid state, since the ions are not mobile.? However, when in solution or in the molten state, ionic compounds
will conduct electricity by the movement of ions.In this
investigation, two electrodes will be placed on paper soaked in brine and an
electrical current will be applied.? The
sodium chloride is in a solution with water so that the ions are free to
disassociate.? The sodium ions should
migrate to the negative electrode and the chloride ions migrate to the positive
electrode, causing an electrical current to flow.? Having singled
out the most influential factor, and researched into the formation and
qualities of the sodium chloride compound, I have formed a prediction.? I predict that the higher the concentration
of sodium chloride in the brine solution, the lower the resistance.? This prediction is based upon the fact that
at a higher concentration, there will be more sodium chloride ions creating
lower resistance.Method: 1.?????? Connect the circuit,
ensuring that the voltmeter is in parallel with the brine soaked paper.To investigate
the resistance of brine soaked paper; I will set up an electronic circuit. I
will utilise a battery, variable resistor, wire, voltmeter and a milli-ammeter.
I am using a
milli-ammeter because the difference in current is likely to be minute and this
will give me a more accurate reading.? I
am using a variable resistor so that I can take several readings (repeating my
results) to form an accurate investigation. 2.?????? Measure out 10 ml of
solution in six test tubes.The salinity
will be varied by diluting a 1M solution of brine to different ratios of salt
to water. To obtain
accurate readings, the same amount of brine will be used for each result
(10ml).? This will be measured using a
measuring cylinder.? 3.?????? The paper will be placed
in a test tube of brine for the specific time of five seconds ensuring that the
paper is completely coated in brine.?
The paper will only be soaked for a specific time because over a longer
period paper will absorb a greater amount of liquid.? By controlling the time, I can create a fairer experiment.The amount and
type of paper will be identical for each reading.? I will use a 6×2 cm rectangular sized piece of paper.? If I used differing sizes of paper then my
results would be inaccurate as more brine could be absorbed or the greater
amount of paper would create a higher resistance.? 4.?????? The brine soaked paper
will be connected into the circuit using crocodile clips.? To prevent contamination or loss of brine,
forceps will be used to transfer the paper from the test tube into the circuit.5.?????? To discover the
resistance of the brine soaked paper; I will record the voltage and current at
each concentration repeating each reading three times and then formulate the
resistance using the formula:Resistance = Voltage ?????????????????? ?? CurrentI will then
take the average of my readings to ensure accurate results and reduce the
effect of any inaccuracies.Obtaining Evidence/Analysing Evidence ?And Drawing Conclusions: I have
tabulated the results of the experiment so that any patterns will become more
apparent and I can distinguish whether my hypothesis was correct.? The concentration column in the table states
the percentage of brine as opposed to water used to test each reading.? 1. Concentration Current Voltage Resistance 2. Concentration Current Voltage Resistance After taking
these readings, I realised that although both tables 1 and 2 show a similar
trend, the actual figures are very different.?
They vary from a resistance of 468 ohms at one reading to 235 ohms at
the same concentration.? Although I had
been careful to keep the same brine for each reading and controlled the other
key variables, the readings had been taken on separate days.? The milli-ammeters I used were different
causing the recorded current to also be different.? I decided to repeat the entire experiment again repeating
readings on the same day (See Table 3).I have
formulated the readings into a graph to help illustrate any patterns in the
data, find the anomalous results caused by mistakes in the investigation and
try to determine the validity of my original prediction (See ?Graph 1?).? The graph
illustrates a very distinct relationship between the concentration of salt and
the resistance of the brine soaked paper.?
It depicts that brine is inversely proportional to resistance. The
greater amount of brine, the lower the resistance.When the paper
was soaked in water only (concentration 0%), there was a very high resistance
yet some current passed.? This may have
happened because tap water was used and it may have contained traces of metal,
which could carry current.? At a concentration
of 20%, the resistance dramatically reduced decreasing from 390 ohms to 48
ohms.? It then steadily reduced as the
concentration increased producing the curve on the graph.These results
appear to prove my original hypothesis ?The higher the concentration of sodium
chloride in the brine solution, the lower the resistance?, as all of my
readings reflect this prediction. However, to be certain of this, I would need
to form a more detailed investigation, correct any anomalous results and create
an even more accurate and fair test. Evaluating: My results
seem reliable as the data produced a graph with a clear line of best fit.? However, discrepancies could have caused
slight inaccuracies in this investigation.?
As I mentioned earlier, I used tap water to dilute the brine to gain
different concentrations.? This meant
that with no salt, some current was able to pass due to the impurities in the
water.?? To create a fairer test, I
should have used distilled water.In this
experiment, I took readings at six different concentrations repeating each
three times.?? If I were to repeat the
entire experiment, I would be sure to record at least ten readings repeating at
each concentration five times.? To
enable readings that are more accurate a more advanced ammeter could be used
because the difference in current is small.?
The readings taken from the ammeter I used, were only for three
significant figures and so inaccuracies occurred.When I
repeated results, the readings were similar however, as I was working with
milli-amps, slight differences increased after the resistance was formulated.By observing
the graph, you can see that in this investigation there were no obvious
anomalies.? As I repeated and averaged
my results, any minor inaccuracies were cancelled out.? I feel that
overall this investigation was accurate and it opens up further possibilities
for future experiments.? These include
investigating whether the thickness of the paper or length of paper would
greatly influence the resistance.