Experiment 6 - Atomic Spectrum of Hydrogen

Time was an issue for the majority of the students today. It helps to split your section in half, and to set up the yardsticks for them, writing the length of the tape on the tape. One half starts with Part I and the other half can choose either II or III. After an hour, make the groups switch. Give several announcements of time remaining to keep them on task.

Goggles are not required for this lab, except for Part III using the hydrogen discharge tubes. There are no makeup labs allowed except for students making up this week's experiment.

Part I:
Tape the LED to the 9V battery so that it stands up easier. When taking a measurement, they should cover the LEDs not being measured to make it easier to identify which spot they are looking for.

To connect the voltage clips to the computer they need both the gray Go!Link Adapter and the black USB Adapter. When they detect the voltage, make sure that they attach the clips to the metal rather than to the plastic.

Graphing:
Once they have a trendline equation, they must change the formatting such that their slope has 3 sig figs. To do this, right click on the equation, click on "format trendline label", and click on "scientific" to display 2 decimals. Even though it says to do this in their manual, and I discuss it in prelab, several groups still omit this step and have slopes of "2E-06". Have your students login to the network to print.

Part II:
There is a typo on Page 6-11 under #6 on the 2nd line - it should direct them towards Table 6-2, not 6-1.

Some students get confused with typing in the equations in excel, particularly the cell references. Show them to click on the cell they want in the equation rather than typing in the corresponding letter and number of the cell - this way they understand better which numbers they are subtracting and how they relate to the equation.

Even with the example of the electron transition diagram for Q7, some students still get confused. They do not understand how to change their axis to match the scale in the manual. Have them divide their values by 10^-18 to get the same scale.

Part III:
The spectroscopes must be rotated to the correct angle for the lines in the spectrum to be visible. Check it out before the students come in because they will surely ask you for help. It helps to turn off the lights in that area of the lab. Your students must wear goggles for this portion.

Q10 was difficult for some students. Guide them to the same calculation they used for prelab Q2c and the example on p6-9. Even with this hint, some of them don't know that 1/∞=0

About this Entry

This page contains a single entry by amaxwell published on March 7, 2011 4:55 PM.

Experiment 5 - Chemical Calorimetry was the previous entry in this blog.

Experiment 7 Part I - Food Dye Spectroscopy is the next entry in this blog.

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