Lab 7 Biodiesel Analysis As you are figuring out your lab s question that you will be research one of the obvious question will be what tools do we have to answer the question It comes down to a need to analyze the product that you obtain in some fashion There are a number of different methods that you can use in the lab I will attempt to give a brief description of what each method can do and a brief synopsis of how it can be done Your LAs will be able to help provide deeper descriptions for any that you wish to pursue They may be able to do this immediately or may need to further consult with the faculty Also keep in mind that there are other processes that you might be interested in pursuing The following list should not be viewed at a complete or exclusive list Simply some items that you may contemplate Possible analysis techniques include yield Calorimetry Thin layer chromatography Viscometry Single temp or as a function of temperature Freezing point FTIR Volatility analysis GC Yield product yield This analysis technique is a quantitative analysis that can be extremely helpful in situations where your section is trying to optimize the reaction looking perhaps at effect of the addition of different amounts of catalyst or different temperatures of reaction The challenge in using yield is that the theoretical yield may be very challenging to determine Instead you may simply need to consider product yield how many grams is produced gram of starting material Keep in mind that this requires the assumption that all products produced are of equal purity Calorimetry This process will involve combusting a known amount of your product and determining the amount of energy given off We will be discussing this process following the 3rd exam in lecture Check out chapter 6 in your book especially 6 2 This process can be done by burning a known amount of biodiesel or oil in a crucible and using the released energy to heat a known amount of water to determine the amount of energy released This method would be really good for comparing different kinds of biodiesel formed from different oils or using different alcohols perhaps Thin Layer Chromatography TLC TLC is a very common method for trying to determine how many different compounds are present in a sample often used in organic chemistry and biology This test provides qualitative information about how many different compounds are present in a mixture It also allows you to determine if two different samples contain different materials For this analysis technique very small quantities of the samples will be placed on the special TLC plates The plate is put in a container with a solvent or solvent mixture The solvent runs up the plate and will separate the different kinds of molecules based on polarity differences and size differences Viscometry Viscometry is the process of testing the viscosity of a substance Vegetable based oils tend to be fairly viscous and don t flow too easily which is bad for a fuel Biodiesel containing smaller molecules tends to flow relatively easily Using viscometry you can compare the viscosity of different oils with the biodiesel they produce to ensure that a reaction did indeed occur and also to compare biodiesels from different oils Since viscosity varies with temperature you can test this at different temperatures to see how the different biodiesels act is there one not suitable for Michigan winters We have a few calibrated viscometers but you can also use a burette to get highly accurate comparative measures A viscometer simply measures the length of time it takes a certain amount of fluid to get through a small tube For the burette you can test the length of time that it takes a solution to drain through the burette from 10 to 5 mL or whatever specific marks you decide to use The quicker the time the lower the viscosity Freezing Point determination You can determine the freezing point of sample of your biodiesels You can first attempt to use a salt ice bath temp of about 10 C to see if your biodiesel will solidify If it doesn t you may have to switch to use a dry ice methanol bath These get much colder and should be able to freeze your sample Once your sample solidifies should only need a few mL to do this you can then let it warm up to find the temperature at which it begins to melt Remember that it should maintain this temperature until all the biodiesel melts if it has a very precise melting point which it might not Different biodiesels should have different melting points FTIR Hey you should know what this does You can use this to compare differences between samples It should also allow you to determine if you have any excess alcohol still present or if you have carboxylic acids present I suspect that you should also see a shift in the carbonyl stretch between the triglyceride and the methyl esters You know what is necessary to do this test Volatility analysis This is simply a quick test to see if you have volatile compounds still present after you isolate your biodiesel One of the possible impurities that could be present in your biodiesel is excess alcohol In theory you should be able to simply evaporate this off by heating it If you heat a precisely know weight of your biodiesel to a temperature above the boiling point of your alcohol you should be able to remove it Careful weighing afterward will allow you to determine if there was a mass change If there was that MAY indicate that you still have some alcohol left in your biodiesel FTIR may help you determine this Gas Chromatography GC This is a technique that allows for separation of mixtures based on their boiling point This tends to be far more effective than TLC but require significantly more equipment We are not sure if we will be able to have this functional in lab prior to your analysis week Other techniques Keep in mind that this is not a full list You may find other techniques recommended that you think would be interesting to attempt For example if you are willing to try this stuff in your diesel car woohoo Free gas you are welcome to try it please talk to the prof first just so we can warn you of the potential problems There certainly are many others Also keep in mind that you can make quite of few observational comparisons These can be based on things such as color opacity observations during heating appearances of solid soap etc Do not discount such information as it can be very valuable in comparing different synthetic processes