larkinwilson wrote:We do not understand the final Table 2 "Average Ratio of Water to Oil question." For example, if we do 3 trials of a sorbant such as fur and our starting total water to oil level is 4 cups (3 c water, 1 c oil) and we get the following results:
Trial 1:
Total water and Oil Level (A) 3.5 cups
Remaining Water Level After Removing Sorbant (B) 3 cups
Remaining Oil Level after removing sorbant (A-B) 0.5 cups
What is the ratio of remaining water divided by remaining oil (B/(A-B)) and what does that tell us?
The ratio is B / (A-B) = 3 / (0.5) = 6.
Because your ideal sorbant will remove oil without removing water, it's nice to have a single number that reflects both of these results. A high ratio of remaining water to oil means that there is plenty of water left and little oil, while a low ratio means not much water but lots of oil remains. Your starting ratio (no sorbant) is 3 / 1 = 3. Thus, a ratio higher than 3 means a sorbant did what you hoped and removed oil, while a ratio lower than 3 means it removed more water than oil.
larkinwilson wrote:And finally if in the 3rd trial:
Total water and Oil Level (A) 2.5 cups (2 cups 4 oz)
Remaining Water Level After Removing Sorbant (B) 2 cups 3.5 oz
Remaining Oil Level after removing sorbant (A-B) 0.5 oz
What is the final ratio of remaining water divided by remaining oil (B/(A-B))?
THANK YOU FOR YOUR HELP
Here you must convert 2.5 cups (or 2 cups and 4 oz) to ounces before you can divide by the remaining oil volume (0.5 oz) because the units must be the same when you divide.
2.5 cups = 20 oz.
B / (A-B) = 20 / (0.5) = 40.
However, you should not have a different starting volume in the third trial- you should rinse out the measuring cup and set up the experiment fresh for each test. Each individual "trial" is supposed to serve as a replicate- you try the experiment three times, doing your best to keep everything exactly the same. That way, any differences that you see must come from some random chance that cannot be controlled. Sometimes you'll see a weird fluke result, so it's important to try multiple times to make sure you're right. Seeing how much variability there is between trials gives you a sense of how much error naturally comes from just doing the experiment. Taking the average measurement of the three trials should give you a more accurate sense of your result than if you'd just tried it once. Thus, each trial should start with the same amount of liquid in the cup.
Say you do three trials for fur and get ratios of 2.8, 3.4, and 6 (totally made up numbers). Take the average of these (2.8 + 3.4 + 6 = 12.2 / 3 ≈ 4.1) and report this value as the final ratio for fur. Having just one number per sorbant tested makes it easy to compare the effectiveness of the different materials, lets you graph your results, etc.
Hope that makes sense! Let me know if you have more questions.
Megan