Viscosity lab. Research question:- How is the viscosity of water affected by changing temperature?

Raw Data:-

The following data was constructed for both hot water and cold water.

Cold water results:-

Hot water results:-

Note: All data are to 3.s.f while all uncertainties are to 1.s.f.

Uncertainty of the volume was written on the graduated cylinder (± 1ml)

Uncertainty of time for each row was calculated using the following:-

Processed Data:-

Below are the processed data tables for cold water and hot water respectively:-

Cold water results:-

Hot water results:-

Note: All data are to 3.s.f while all uncertainties are to 1.s.f.

-Uncertainty of time was calculated by taking the average of uncertainties for cold and hot water respectively.

-“Time elapsed” was calculated by taking the average of trials for each row for both cold and hot water.

-Some data had to be rounded to three significant figures.

Data presentation:-

Rate of viscosity (since it is measured relative to time) equals:-

Re writing:-

Hence a graph between Volume (on x-axis) and Time (on y-axis) should yield a slope of , from which the rate of viscosity can be calculated.

Cold water graph:-

Hot water graph:-

Conclusion:-

As explained before, the inverse of the slope of the graph represents the rate of viscosity, so:-

Analysis for cold water:-

Hence:-

Analysis for Hot water:-

Hence:-

Data is now sufficient to draw the conclusion that:-

This experiment showed that the rate of viscosity of hot water is greater than cold water, even within the range of uncertainties the conclusion is still valid.

This can happen because the hot water that interacted with the opening of the burette made it hotter, thus giving its particles energy to draw away from each other, resulting in a small increase of the radius of the opening of the burette, thus making water run down the burette faster.

Moreover, when water is heated near its boiling degree, its particles will have a lot of energy so that they start colliding with each other more quickly, so when the burette stopcock is opened, the molecules keep colliding and rush down the burette’s opening more quickly than cold water.

Evaluation:-

This experiment had some sources of weaknesses and limitations which yielded uncertainties, that being noticed that the graph doesn’t start from the center from the two axes, it is a little bit deviated, this can happen because of :-

Weaknesses:-

-Although the stopcock was opened at full 90 degrees, during some trials the stopcock might have been opened faster than others, resulting in time uncertainties.

- After all, the volume of falling water was read off the graduated cylinder using the naked eye, which have yielded some volume uncertainties.

- The stopwatch was might have been triggered at wrong intervals as humans are subject to errors, yielding time uncertainties.

Limitations:-

• The used stopwatch gave numbers rounded to three significant figures, using a stopwatch with a larger number of significant figures could have gave more accurate values,
• The used graduated cylinder had a relatively high uncertainty (± 1ml) using a cylinder with less uncertainty might have yielded more accurate results.

Improving the investigation:-

• Developing a better method for maintaining the heat of water (weather hot or cold) inside the glass burette. (maybe using material with a higher specific heat capacity would help).
• Using a stopwatch with a higher number of significant figures.
• Using a graduated cylinder with a smaller uncertainty value.
• Developing a better method for opening the stopcock at the same speed for all trials to guarantee an equal speed for the flow of water.