Intermolecular bonding in liquids

[chem410]

I have done an experiment in which I measured the time and depth of the vortex of water, paint thinner (varsol), and vegetable oil. Water had the deepest and longest lasting vortex, paint thinner was a little less, then oil had a very minimal vortex that was gone right away.

Now I'm trying to answer the following questions, but am not sure if I am on the right track...I know some other posts have somewhat addressed this, but I would like a better explanation.

1. Name the types of intermolecular bonding present in each of the liquids.
2. In terms of intermolecular bonding, explain the relative differences in time taken for the vortex to disappear in each liquid.
3. Why is water so much different from the other 2 in time and depth of vortex?
4. Why would sugar dissolve in water faster than salt (w/ same agitation and temp.)?

This is what I have:

1. The types of intermolecular bonding present in each of the liquids are:
o van der waals forces – paint thinner
o hydrogen bonding – water
o dipole-dipole bonding – vegetable oil

2. ?

3. Water is so much different in terms of time and depth of vortex, because it is a smaller molecule. Since it is a smaller molecule, you can tranfer kinetic energy to it more easily. The water is able to gain more momentum, and thus the depth of the vortex is greater and takes longer to disappear. Oil contains oleic acid, which is a larger molecule, making it more difficult to transfer kinetic energy to. Paint thinner contains small molecules like toluene (which is still bigger than a water molecule), which is why it is between water and oil in terms of time and depth of vortex.

4. With the same type of agitation and at the same temperature, sugar dissolves faster in water than salt because sugar is covalently bonded while salt is contains ionic bonds. The covalent bonds in sugar make sugar molecules weaker, and the ionic bonds in salt make them stronger and harder to separate. A greater number of bonds are able to form between sugar and water compared to salt. This is because the salt ions are smaller compared to the size of the sugar molecules. Sugar has a greater solubility than salt.

 

[nate808]

2. In terms of intermolecular bonding, the relative differences in time taken for the vortex to disappear in each liquid can be explained by the strength of the intermolecular forces present. Water has strong hydrogen bonding between its molecules, which allows for a strong cohesive force to form the vortex and maintain it for a longer period of time. Paint thinner, on the other hand, has weaker van der Waals forces between its molecules, resulting in a less stable vortex that disappears quicker. Vegetable oil has dipole-dipole bonding, which is weaker than hydrogen bonding, resulting in an even shorter-lived vortex.

3. Water is so different in terms of time and depth of vortex because of its unique hydrogen bonding. Hydrogen bonding is a strong intermolecular force that allows for a high degree of cohesion between water molecules. This cohesion results in a strong and stable vortex that takes longer to disappear compared to the other liquids. Additionally, water molecules are small and can easily transfer kinetic energy, allowing for a deeper and longer lasting vortex.

4. Sugar dissolves faster in water than salt because of the difference in the strength of their intermolecular forces. Sugar has covalent bonds between its molecules, which are weaker than the ionic bonds present in salt. This allows for a greater number of bonds to form between sugar and water, resulting in a faster dissolution. Additionally, the size of salt ions is smaller compared to the size of sugar molecules, making it harder for them to interact with water molecules. This results in a lower solubility for salt compared to sugar.

 

[Blueshift5]

A more precise answer would be:

1. The types of intermolecular bonding present in each of the liquids are:
o van der Waals forces – paint thinner (varsol)
o hydrogen bonding – water
o dipole-dipole interactions – vegetable oil

2. The relative differences in time taken for the vortex to disappear in each liquid can be explained by the strength of the intermolecular bonds. Water has strong hydrogen bonds between its molecules, which make it more cohesive and resistant to external forces. This results in a longer lasting vortex. Paint thinner has weaker van der Waals forces, making it less cohesive and easier to disrupt, resulting in a shorter lasting vortex. Vegetable oil has even weaker dipole-dipole interactions, making it the least cohesive and easiest to disrupt, resulting in a minimal vortex that disappears quickly.

3. Water is significantly different from the other two liquids because of its unique hydrogen bonding. Hydrogen bonding is a strong intermolecular force that occurs between the slightly positive hydrogen atom of one molecule and the slightly negative oxygen atom of another molecule. This creates a network of hydrogen bonds, giving water a high surface tension, high boiling point, and high viscosity compared to other liquids. These properties make it more resistant to external forces, resulting in a deeper and longer lasting vortex.

4. Sugar dissolves faster in water than salt because of the difference in the strength of the intermolecular bonds between the solute and solvent. Sugar molecules are covalently bonded, meaning they have strong bonds within the molecule but weaker bonds between molecules. In contrast, salt contains ionic bonds, which are much stronger than covalent bonds. When placed in water, the water molecules are able to break the weaker bonds between sugar molecules more easily than the stronger ionic bonds in salt. This results in a greater number of sugar molecules being able to dissolve in water compared to salt. Additionally, the size of the sugar molecules allows for more efficient packing and interaction with water molecules, further increasing its solubility.