Determination of the Rates and Optimal Temperature for Aerobic Respiration and Photosynthesis. Lab report

Figure 1: The Accumet TM AB15 pH probe. The blue collar is indicated with an arrow in image (A), which shows the probe in the storage solution. (B) shows an active pH meter readout, with the control buttons on the right of the screen.

Ready pH probe:

Prior to use , rotate the blue or purple ring near the top of the probe fully clockwise to open the probe to the atmosphere.

At the end of the lab , turn the ring fully counterclockwise to close the probe . Calibration:

1. rinse and blot probe, place it in the first calibration buffer - pH 7.0 2. press stdby to activate meter 3. press std (standardization) twice in fairly quick succession. The first will access the Standardize screen - check that the appropriate buffer group is selected - it should include 4,A B 7 and 10. The second will begin calibration - the meter will automatically recognize the buffer.

When the meter accepts the buffer, it will briefly display the percent slope associated with the electrode's performance before automatically returning to the Measure screen . If the electrode is within the range of 90-100% efficiency, the GOOD ELECTRODE message will appear. If the electrode is outside this range, the meter will display the ELECTRODE ERROR message, and will not return to the Measure screen until the user presses enter. If this message appears, inform your Instructor. (See back of sheet for troubleshooting help.) When the stable icon appears the meter should read the pH value of the buffer you are using to calibrate it with. Press stdby before removing the probe from the buffer, then rinse the probe and blot dry.

4. repeat steps 1 to 3 with the second buffer – either pH 4 or 10 Measurements :

1. Rinse and blot probe, place it in the test solution and wait for the stable icon to appear before recording the value. Remember to place the meter in stdby before removing the probe from the solution, then rinse the probe and blot dry.

2. Store probe in electrode storage solution when measurements are complete. Remember to close the ring at the top of the probe.

BAD ELECTRODE ERROR When the meter is flashing ELECTRODE ERROR, follow the steps below:

1. press Enter 2. press Setup twice (pH buffer range will be displayed - it should include 4, 7 and 10) 3. press Enter to clear the previous measurement 4. begin calibration procedure again, starting at step 1 2