Question

Tools Window Help OMX 75% Esterification Experiment Lab Data.pdf (page 1 of 3) Search Product Ester IR of starting alcohol (1-pentanol) 1-Pentanol M. AM 19ra aromo 14, 2017 m. 1% 1075 20 . 2030 26.1.60.39 10 4000 3500 . 1000 3000 INT 650 2500 cm-1 2000 1500

Answer 1

Solution:

18) Ester: A band at 1740 is a characteristic peak of ester due to -C=O stretch

Ketone: A band at 1680-1720 would be characteristic peak of ketone due to -C=O stretch

water: A broad band at 3700-3100 cm-1 would be a characteristic peak of water molecule due to -O-H stretching.

Alkene: A band at 1620-1680 cm-1 would be a characteristic peak of -C=C- and a band above 3000 would be for -C-H stretching of alkene.

[By observing FTIR spectra of ester provided above do no show presence of ketone, water or alkene]

19)  Hydrogen bonding is not a covalent bond it is formed due to dipole-dipole attraction between molecules. It is bond between a hydrogen atom [which is covalently bonded to a very electronegative atom such as a N, O, atom] and electronegative atom such as N, O of another molecule. It is relatively weaker bond than co-valaent bon.

Covalent bond : It formed due to sharing pair of electron between to atoms which are going to form a bond. This type of bonds are relatively strong.

Covalent bond Hydrogen bonding Covalent bond

20) There are only two functional group are observed above 1500 cm-1 frequency. those are ester and -CH3 or -CH2 groups. Their details are provided in table below.

Pure ester peak %T Functional group Pure ester peak cm-1 1740 specific bond vibration -C=0 stretching 52 2810 -3000 75 -CH3 or – CH2 Aliphatic -C-H symmetric stretching

21)

22) If there would be an unreacted alcohol in ester then in FTIR spectrum of ester there would have broad band at 3319 cm-1 which is characteristic peak of alcohol.

alcohol peak cm-1 alcohol peak %T Functional group specific bond vibration -O-H stretching | 3319 85 -OH alcohol 2863 -2954 -CH3 or – CH2 Aliphatic -C-H symmetric stretching

23) Thermal energy = mass of reactant × specific heat capacity of reactant × change in temperature

change in temperature:

For heating its difference betwen room temperature and higher specific temperature.

For cooling its difference between higher temperature and room temperature.

24.The ethanol has a much higher boiling point than dimethylether, because of hydrogen bonding in ethanol molecules, it is relatively harder to separate them from each other. In case of dimethyl ether no hydrogen bonding observed.

25. In case of dibutyl ether is high molecular weighed compound and in its structure a long chain of carbon is present which indues the London dispersion forces that make this compound high boiling. Even though ethanol is having hydrogen bong but due less carbon numbers it will have low boiling point than dibutyl ether.

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