Chemistry, 15.07.2019 14:30, unknown6669

Choose the substance with the lowest viscosity. choose the substance with the lowest viscosity. f2chchf2 f2chch2f fch2ch2f f3cchf2 f3ccf3

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answered: Boris1002

Answer : $FCH_{2}CH_{2}F$

Explanation : In the molecule of $FCH_{2}CH_{2}F$ the hydrogen bonding forces tend to resist any phase transition form liquid state to gaseous phase, and these hydrogen bonding forces are greater usually when the hydrogen is bound to an electronegative atom like chlorine, fluorine,oxygen,etc. This then lowers the viscosity of the compound.

answered: bmartinez26

The substance with lowest viscosity is $\boxed{{\text{FC}}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{F}}}$ .

Further explanation:

Viscosity is defined as the resistance of any liquid to flow. Stronger the intermolecular forces of attraction within the liquid, larger will be its viscosity.

Intermolecular forces:

The forces that exist between the molecules are known as intermolecular forces (IMF). They are electrostatic in nature and determine the bulk properties of the substances like melting and boiling points. Molecules are held in any substance due to these forces.

The various types of intermolecular forces are as follows:

1. Hydrogen bonding.

2. Ion-dipole forces.

3. Ion-induced dipole forces.

4. Dispersion forces

Hydrogen bonding:

It is an attractive force that exists between hydrogen and more electronegative elements like N, O, F. It can either be intermolecular or intramolecular. Intermolecular hydrogen bonding is the one that occurs between different molecules. For example, the bond between HF and ${{\text{H}}_{\text{2}}}{\text{O}}$ is an intermolecular hydrogen bond. Intramolecular hydrogen bonding occurs between various parts of the same molecule. Ortho-nitro phenol and salicylaldehyde show this type of bonding.

With an increase in the number of fluorine atoms in the compound, the polarity of the compound increases. Due to increase in polarity of compound, the tendency to form hydrogen bonds with water molecules also increases and that is the reason for increase in viscosity or the compound.

${{\text{F}}_{\text{3}}}{\text{CHCH}}{{\text{F}}_{\text{3}}}$ has the highest number of fluorine atoms among all the compounds, so it has highest tendency to form hydrogen bonding that attributes to its highest viscosity.

${\text{FC}}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{F}}$ has lowest number of fluorine atoms among all the compounds, so it has lowest tendency to form hydrogen bonding that attributes to its lowest viscosity.