The rate of a chemical reaction Essay Example for Free

The rate of a chemical reaction EssayThe equation for safeguard using resistivity is enemy = resistivity x continuance / body politic of cross section of the electrify The resistivity of Nichrome at 250C is 100 x 10-8 ohm-m. The radius of the conducting cable isResistance = resistivity x length / ara of cross section of the telegraph Resistance = 100 x 10-8 x 0. 4m / 6. 16m2 x 10 -8 Resistance = 6. 49 ? rounded 2 d. p.TPlan Aim I aim to find out if the length of a Nichrome wire affects the unsusceptibility. Safety To ensure this experiment is safe I entrustEnsure that the power postulate does non exceed 2 volts in case the wires overheat. I impart also only set out the power pack on for short amounts of time so the wire does not overheat. I provide not perform the experiment in a wet area because water is a precise good conductor of electricity and so this would be very dangerous. I will not come to the wire once the power pack is switched on because the curre nt will heat up the wire. Factors to go out The independent vari fit will be 1 The amount of unsusceptibility in different lengths of wire. The unsettleds that I will support the same will be2 Width of wire- I must living the wire a thickness of 32SWG. If I convince the width of the wire the resistance will change because at that place is to a greater extent resistance in a thicker wire because on that point are more decided ions so there are more collisions in the wire and more successful collisions means the resistance will increase 3 Material of wire- different materials will affect the amount of free electrons that are able to buy the farm through the wire. If there are more or larger atoms because there will be more collisions. This causes the potentiality of the wire to increase causing a higher resistance. as well if the atoms in the material are more closely packed then the electrons will boast more frequent collisions and the resistance will increase. I will u se Nichrome only. 4 Density of wire- In a higher density wire there will be a higher resistance because there will be more fixed ions and more collisions. 5 Temperature of wire- If the wire is heated up the atoms in the wire will start to vibrate because of their increase in susceptibility. This causes more collisions between the electrons and the atoms as the atoms are moving into the path of the electrons. This increase in collisions means that there will be an increase in resistance.6 Shape of wire- the wire will be straight and taped to a meter rule, the pulp of the wire may increase the resistance. 7 Voltage of 2 volts- I will sustain to keep a constant potentiality because if the voltage changes then the resistance will change. The equation for resistance = voltage / current. If voltage increases, resistance increases. Apparatus The apparatus I will need to perform this experiment will be 1 Power pack (2volts) 2 Ammeter 3 Voltmeter 4 6 wires 5 2 crocodile clips 6 Meter rul e 7 Masking tape 8 Board marker perimeter diagram Method I have chosen to take a range of 10 lengths.I have chosen a range of 10 as to plot an accurate interpret I will need at least 10 points to mark on the graph. The lengths that I have chosen are as follows 10cm, 20cm, 30cm, 40 cm, 50cm, 60cm, 70cm, 80cm, 90cm and 100cm. I have chosen these lengths because the meter ruler undersurface slowly measure them and enough results to come across a firm conclusion. To change the length of the Nichrome wire during the experiment I will tape down 1 meter of Nichrome 32 swg wire to a meter rule. I will then connect the 2 crocodile clips different distances apart using the measurements on the meter rule.The wire will be attached at X in the circuit. In my experiment I will find the current in the circuit using an ammeter and I will find the voltage in the wire using a voltmeter. I will take these two readings so I can then calculate the resistance using the equation resistance = voltage / current. I want to make my experiment as accurate as possible so I want to levy extract readings so that I can find an average resistance. I will be using a variable immunity in my experiment to produce these iterate readings. I will draw 4 equ whollyy spaced points on the variable resistor with a board marker.To get my repeat readings I will move the variable resistor to these 4 points and get four readings for each length. After I have found the average resistance for each length of wire I will produce a graph showing the average resistance against the length of the wire. I will draw on my graph a line of best fit and then from this I will be able to see if my prediction was correct and if the resistance does increase when the length of wire increases. 1. Set up a circuit as shown above. Set the power pack at a constant voltage of 2 volts. 2. At X in the circuit the wire will be placed.I will scratch connect the crocodile clips 100cm apart. Then eddy the voltmeter and am meter on and ensure the variable resistor is set at the first point. 3. straight off turn on the power pack and evidence the first results shown on the ammeter and voltmeter. I must take the first results because the results may change due to overheating if the power pack is left on. Now turn off the power pack. 4. To take my repeat reading of 100cm I will then move the slider on the variable resistor to the second marked point. I will now turn on the power pack and record the first result shown on the ammeter and voltmeter. 5.I will go along taking my repeat readings and moving the variable resistor along and recording the results for 100cm. 6. I will then change the length of wire to 90cm by moving the crocodile clips and i will set the variable resistor at the first point. Then I will turn on the power pack and record the first set of results. I will take 4 repeat readings for each length of Nichrome wire. 7. I will record 4 repeat readings for each length of Nichrome wire unt il I have results for all 10 lengths.Results table Length (cm) Repeat number Voltage (volts) Current (amps) Resistance (? ) Average 17. 82 I have put in bold any mistaken results. Analysing and considering evidence Conclusion From my graph I can tell that my prediction was correct. As the length increases the resistance increases, a member of 20cm wire has a resistance of 3.8 ? and a piece of 30cm wire has a resistance of 5. 6 ?. This is because a longitudinal piece of wire has a higher resistance because in a longer piece of wire there are more collisions between the electrons and the metal ions.In every successful collision energy is lost from the electron to the wire ions. The result is that the voltage of the wire increases. Because the equation for resistance is resistance = voltage / current, the resistance then increases. From my line of best I can also tell that as the length two-folds the resistance always some doubles in any case.A piece of 20cm wire has a resistance of 3.8 ? and a piece of 40cm wire has a resistance of 7. 4 ?. Double 3. 8 ? is 7. 6 ? this is intimately double only if not rather belike because my experiment was not quite accurate. A piece of wire 30cm long had a resistance of 5. 6 ? and a piece of wire 60cm long has a resistance of 11. 1 ?. This is also almost double, double 5. 6 ? is 11. 2 ?. The resistance doubles as the length doubles because there can be double the amount of successful collisions so double the amount of energy is lost causing the voltage to double and so the resistance doubles. Key negatron Metal ion Predicted results Length (cm)Predicted resistance ( ? ) Actual resistance ( ? ) Difference (ll of my results were quite close to my predicted results but as the length increases my predicted resistances become less accurate. This could have been for several reasons that are mentioned in my evaluation but probably as my experiment went on the wire overheated so my results became less accurate.Evaluating My method of collecting my results worked quite well. I gained the results I expected from my experiment. The quality of my evidence was good. My line of best fit went through almost all of my points on my graph and was quite similar to my predicted line of best. I did have some paradoxical results. When I experimented with 10cm of Nichrome wire my fourth repeat readings was quite different to the other readings. It had a resistance 0. 87 ? that was the lowest repeat readings for 10cm. The second lowest was 1. 80 ? , this is quite a lot more than the anomalous result.When investigating which 30cm of Nichrome wire I had another anomalous result that was 6. 48 ? , the third repeat reading. This was the biggest repeat reading. The second largest was only 5. 89 ?. This could have been because I left the power pack on too long. This causes the wire to overheat. When I was measuring the lengths of the Nichrome wire my measurements might have been slightly inaccurate. The rulers used might n ot have been exact and it was difficult to get an accurate reading of length by eye as the wire was not completely straight.Also the ruler may have been of different thicknesses throughout the length. This would have contributed as a slight error in my results. The ammeter and voltmeter could have been slightly faulty and not given(p) me correct, accurate readings. I connected the wire into the circuit using crocodile clips. These were quite loose and so this could have made my results less accurate. If I improved my method I could either attach the wires with tape but this may affect my results so preferably I could solder the Nichrome wire into my circuit.It was difficult to adjust the variable resistor slider accurately only by eye. If I did the investigation again I could pronounce to and adjust the variable resistor accurately I will use an advanced digital variable resistor. I also found it difficult to measure exact lengths against the meter rule because the crocodile clip s didnt clip on to the wire very securely. If I did the investigation again I could pre cut all the lengths of wire originally the experiment instead of just connecting the crocodile clips at different distances apart on the meter rule.To further my investigation I could use the same method but increase the range of lengths. I could use lengths of up to 3 meters. I could take readings from lengths at smaller intervals I could take reading every 5cm instead of every 10cm as I did. I could also take more repeat readings to get a even more accurate average. Show preview only The above preview is unformatted text This assimilator written piece of work is one of many that can be found in our GCSE electricity and Magnetism section.