The equipment that I use will be accurate and reliable. The measuring cylinders have very precise markings of the volume in ml³. All the measuring cylinders will have the same volume and they will also have the same height of 25 cm to make the test fair because I am measuring the time taken for an object to fall through different concentrations of liquids. I plan to use different cylinders for measuring the wallpaper paste and water for each experiment instead of rinsing out and drying because if even a little bit of water is left in the cylinder the results will become inaccurate.
I will use another person to start the stopwatch, as I release the ball, because otherwise I might take longer to start the stopwatch and so the results would become less accurate. I will also measure out the solutions on a flat surface, making sure the meniscus lies on the measuring line because a little bit of inaccuracy of measuring the solutions will lead to unreliable results.
Factors:
- I am going to keep the temperature constant at the normal room temperature, as temperature can change the viscosity of substances.
- I am going to keep the amount of all the solutions the same so that they all measure 100ml. However I am going to change the concentrations.
- All the cylinders will measure the same volume and have the same height of 25 cm. This is because I am measuring the time it takes for an object to drop through different concentrations of liquids, however if the height is different for any of the experiments, it will be an unfair test. Therefore making my results inaccurate and not valid.
- I am also going to mix the wallpaper paste and water in a beaker for two minutes each, so that the substances are mixed evenly.
Method:
- Collect the measuring cylinders, and measure the correct amount of wallpaper paste and in the cylinders that are going to be used to measure water, measure the correct amount of water. Then for the solutions that have a mixture of wallpaper paste and water, pour the solutions into the beakers and mix for 2minutes each using a glass rod. After they are mixed pour into the cylinders.
- Collect and label 5 cylinders with the different concentrations of solution on each cylinder. The solutions will be labelled, 100% Wallpaper paste, 80% Wallpaper paste, 60% Wallpaper paste, 40% Wallpaper paste, 20% Wallpaper paste and 0% Wallpaper paste. Place a piece of card over each cylinder and on top place the blue-tack ball.
- Make sure the stopwatch is ready.
- Pull the card from over the cylinder; this will release the blue-tack ball into the solution. At the same time, however, start the stopwatch.
- Stop the stopwatch once the ball reaches the surface of the cylinder.
- Carry out this procedure until the results have been taken down for all 5 of the solutions.
- Repeat the experiment 3 times so that any anomalies will stand out.
Prediction:
I predict that the solutions that are more viscous for example the solutions that are 100%, 80% and 60% wallpaper paste will take more time to reach the surface of the cylinder. The reason being viscosity is the resistance of a fluid to flow. Diluting or heating the solution can alter the viscosity of a fluid. In this experiment the solutions have been diluted and so therefore the more diluted solutions such as the solutions, which are 40%, 20% and 0% wallpaper paste will reach the surface of the measuring cylinder much faster then the more concentrated viscous solutions.
Obtaining Evidence
Results Table
Analysing and considering Evidence
After looking at the results, I have found out that the less the concentration of the Wallpaper Paste the less time it takes for the object to flow through the liquid.
I have produced two graphs, one showing all three of the experiments and the other showing the averages of the experiments. The graphs I have produced are curves with positive gradients. They have been plotted against the percentage concentration of wallpaper paste. The trend they follow also shows that, as the percentage concentration of wallpaper increases the more time it takes for the ball to drop through the liquid
The gradients of the graphs are positive because it shows that as the concentration of wallpaper paste increases, the liquid is relatively thicker then when the concentration of the wallpaper paste is diluted. Therefore it shows that for an object to fall through a more viscous substance will take a longer time then when the liquid is more diluted. So because the graph starts with a low percentage concentration of the Wallpaper Paste, the rate of the fall of the blue-tack ball is quick and as the percentage of the Wallpaper paste increases, the rate of the drop of the blue-tack ball is slower, taking longer to reach the surface of the cylinder.
The results that I have produces in the form of the table and graphs support my prediction as they show that the more viscous the liquid the less easily an object falls through, therefore taking a longer time to reach the surface. In my prediction I has expected the solution which were more viscous e.g. the solutions that were 100%, 80% and 60% wallpaper paste will take longer for the blue-tack ball to fall through the liquid then the solutions which were 40%, 20% and 0% concentrated. So I had predicted that the more viscous the solution the longer time it takes for the object to fall through, my results illustrate the same trend.
Evaluating
My experiment was successful because I took great precautions when undertaking the experiment. I used accurate equipment, and observed the reaction throughout under the conditions of each experiment.
My results were accurate because I produced a set of fairly reliable results with no anomalies. Also because I repeated the experiment thrice and plotted an average results graph, it meant that if there were any anomalies then they would stand out more. As mentioned earlier, I used accurate equipment. I used the same type of measuring cylinders; they held the same volume and had the same height so that the experiment would be fair. I used an accurate stopwatch to time the experiment. Therefore my results were as accurate as I could have made them, using the equipment and time available.
The method I used was suitable as it goes through the experiment systematically. Nevertheless, there is always room for improvements; such as I could have used a digital stopwatch to time the reaction as a digital stopwatch measures the time in seconds up to two digital places (0.00 seconds) This would automatically improve the accuracy of the results. Also I could have used the same measuring cylinder for each experiment, only that I would have to rinse and make sure it is dry thoroughly before carrying out the experiment.
Although there is room for minor adjustments, the results seem accurate and reliable because they follow the same pattern. Thus I believe they support my prediction and collusion as both show that the more viscous the substance the less easily an object will fall through it. Also they both show that the wallpaper paste is more viscous than water, because when the solution was 100% wallpaper paste, the average time it took for the blue-tack ball to fall through was 63.3 seconds, however with 100% water the average result was 0.4 seconds. Therefore the wallpaper paste was much more viscous than water.
To further prove my conclusions, I could conduct the experiment, investigating the concentration, however keeping the concentration the same, but changing the temperature of the wallpaper paste solution, to show that by y increasing the temperature, viscosity of the liquid decreases. This would reduce human error, as observing the rate at which the blue-tack ball falls and reaches the surface depends upon the observer.
