Chemistry 534

Lab : The Rate of Water Flow

Purpose:          To study the rate of water-flow from a buret

Procedure:

1.         Fill a buret with water until the meniscus is above the 0.00 mL mark.

2.         Make sure there is no air bubble at the tip of the buret. If there is, open the stopcock to let the air out, and repeat step (1).

3.         Be prepared to time this carefully with a stopwatch or digital watch. You'll be measuring the volume of water at 10- second intervals. Turn the stopcock about 3/4 of the way to slowly let water drip out. You should not see a stream of water but individual drops falling, and you should not have the time to shave in between drops. (No offense, ladies.) Your first reading will be 0.00 mL at 0.0 seconds.

Closed Position

3/4 position

Fully opened position

One person should constantly watch the buret and call out the volume when prompted, while the other person should take note of the 10 s intervals and record the volumes.

Record the results in the data table in INK.

Data:

 Time (seconds) Volume of H2O(mL) (1 decimal place)

Analysis of Data.

1.         Find the average rate of water flow in mL/s from t = 0 to t = 30 s. (2marks)

2.         Find the average rate of water flow in mL/s from t = 180 to t = 250 s. (2marks)

3.         Find the average rate of water flow in mL/s for your last 30 seconds. (2marks)

4.         Does the rate change? Why or why not? What is physically responsible for this? (2marks)

5.         Use the graph paper provided to plot all your data.        (4 marks)

6.         a. Calculate the instantaneous rate of water flow at t = 190 s. to do this draw a tangent line at t = 190s. Then find the slope of this line. Show work.

b. How does this instantaneous rate compare to the average rate from #(2)? Why is it or isn't it the same value?