Unit 1- Viscosity of liquid Post Lab quiz

What is the viscosity if a 20.39 g marble takes 25.33 seconds to drop through 54.93 cm of a liquid?

0.0015

How long (in seconds) would it take for a marble that has a mass of 21.63 g to drop through a liquid with a viscosity of 0.60 Pa· s and is 57.99 cm high?

0.0622

Which of the following is NOT an intermolecular attraction? Hydrogen bonding Dipole-Dipole Covalent bonding Dispersion forces

Covalent bonding

Which of the following would have the highest viscosity? N2 CH4 HOCH2CH2CH2OH HOCH2CH2CH2CH3

HOCH2CH2CH2OH

Why were three runs performed for each liquid? It allows for an average to be calculated which is better than using just one run. So that the lab would take longer. It is easier to understand something when you do it three times. Three is a magic number.

It allows for an average to be calculated which is better than using just one run.

What are the S.I. units of Dynamic Viscosity? Pa s Pa/s cSt mm2/s

Pa s

Why was it necessary to have the same liquid height when repeating the runs? To ensure the same displacement by the marble because the times were being averaged. Since the times for the three runs were being averaged the height needed to be the same. It wasn't. The lab author was just being picky.

Since the times for the three runs were being averaged the height needed to be the same.

When a liquid has a high viscosity what does that indicate about its intermolecular attractions? It does not have intermolecular attractions. The intermolecular attractions are strong. The intermolecular attractions are weak. The intermolecular attractions are the same for all liquids.

The intermolecular attractions are strong.

What happens to the viscosity of a liquid when the liquid is heated? The viscosity does not change. The viscosity decreases The viscosity increases.

The viscosity decreases

Why does the viscosity of a liquid change when the temperature is changed? The viscosity does not change with a change in temperature. When the temperature is increased the molecules have more energy to overcome the intermolecular attractions. The intermolecular attractions are weaker at higher temperatures. The higher temperature makes the marble heavier, so that it drops quicker.

When the temperature is increased the molecules have more energy to overcome the intermolecular attractions.