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1.4: THE NOTEBOOK – MAKING SURE THE NUMBERS ADD UP

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    135938
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    At PSU, it is required to use and keep a notebook. This notebook will be used both in the preparation of the experiment, and during the experiment itself. We will focus on how to use the notebook in the prepara- tion phase of an experiment. In chapter 4.4 we will discuss the use of the notebook during the experiment.

    When stepping into the lab, your notebook should contain the following:

    1. A title and a balanced reaction scheme, if a synthesis is planned. If not, the relevant chemical structures of the compounds of interest should be shown.
    2. A flow-diagram that outlines the experiment, where you have included the most relevant information.
    3. A table or overview that shows all chemicals handled, and their risk and hazard statements.
    4. A synthesis table that shows the quantities of the reagents/reactants that you plan to use, with room to fill in the quantities you actually used.
    5. A table that shows the properties of the reagents/reactants and reaction solvents used in the procedure.

    The synthesis table should contain the most important physical properties of the reactant(s), reagent(s) and product(s). This table should contain the quantities you should measure, A reaction scheme of benzaldehyde as the reactant turning into benzyl alcohol with NaBH4 as the reagent and methanol as the solvent.with room to add your actual measurements. This format allows you to order all the necessary measurements in the same place. An example is shown in table 2. There are many exam- ples where this information is important in lab. If you for example measure 0.4 mL of benzaldehyde, instead of the 0.3 mL the procedure called for, you need to scale the procedure up. That means that the amount of NaBH4 also must be changed. For this process, you need the density of benzaldehyde, the molecular weight of benzaldehyde to find the moles, and the molecular weight of NaBH4.

    Table 2. Example of a synthesis table for reagent(s), reactant(s) and product(s)

    Compound Mw [g/mol] d [g/mL] V [mL] m [g] moles [mmol] Y ield [%]

    Benzaldehyde

    NaBH4

    Benzyl alcohol

    106.7

    37.8

    108.1

    1.044

    -

    1.044

    0.30 _____

    -

    -

    0.31 _____

    0.15 _____

    0.21* _____

    2.9 _____

    3.9 _____

    1.9*_____

    -

    -

    65.6*_____

    * The values for benzyl alcohol is based on the procedure, that states that a yield of 65.6% is expected.

    The table for physical properties is used not only for the reagent(s), reactant(s) and product(s), but also reaction solvent, work-up chemicals and others. This table is very handy in the lab, as the physical properties of the chemicals play a large part in the work-up of any reaction.

    Table 3. Example of a table for physical data

    Compound State Boiling point [°C] d [g/mL] Solubility in water [g/100 mL] Solubility in diethyl ether

    Benzaldehyde

    NaBH4

    Benzyl alcohol

    Diethyl ether

    Methanol

    Liquid

    Solid

    Liquid

    Liquid

    Liquid

    178

    -

    205

    36

    65

    1.044

    Not relevant

    1.044

    0.71

    0.79

    0.3

    Decomposes

    3.50

    6.05

    Soluble

    Soluble

    Non soluble

    Soluble

    -

    Soluble


    This page titled 1.4: THE NOTEBOOK – MAKING SURE THE NUMBERS ADD UP is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Alexander Sandtorv (PDX Open publishing initiative) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.