pH Sensor

Feb 25, 2010

The pH sensor can be used to measure the static pH values of common liquids (water, milk, soft drinks, vinegar, etc.) as well as the changing values in titrations or experiments such as those looking at the effect of antacids.

The pH sensor is designed for long life in a variety of general purpose situations. Its sealed reference system and gel fill make it easy to use and maintain. With an epoxy body it is a durable electrode for use both in the laboratory and in the field.

The operation of the pH sensor is demonstrated in the video below.

pH Sensor from Allan Kerr on Vimeo.

Sensor Calibration

This sensor gives a fast response across the full pH range and can be calibrated with any standard buffer solution. Connect the sensor to a voltage source (the USB Bridge plugged into a PC, Neulog’s™ Monitor Display Unit or Battery Unit), insert the sensor into a pH = 7 buffer and press the black button on the sensor and hold for about 3 seconds. The reading will then be calibrated to 7. Alternatively the sensor can be connected to a PC running the Logger Sensors software via the USB Bridge. First click on the Module setup button on the pH sensor’s Module box to open its Module setup window. Then click on the Calibration icon

The pH sensor can be used in experiments from as short as 1 second and up to 31 days in duration. Sampling rates can be varied from 60 per minute up to 100 per second.

Experiment 1

In this experiment we will investigate the pH of a range of liquids, tap water, bottled water, pool water, Coca- Cola, “V” energy drink, beer, coffee and tea.

The pH values from lowest to highest were

Coca-Cola                                                 2.2

“V”                                                              2.3

Beer                                                            3.2

Bottled water (h2go)                           6.1

Tap water (Epsom, Auckland)         6.3

Ant-acid formulation (Mylanta)    7.2

It is amazing how acidic the soft drinks and beer are. No wonder some people need to take ant-acid tablets or medicines.

Experiment 2

In this experiment we will investigate how adding ant-acid mixture to a glass of Coca-Cola raises the pH.  We gradually poured in some ant-acid solution to the Coca-Cola over a few minutes. The results on the chart below were measured over 1 minute at a sampling rate of 5 per second and showed the pH went climbing from an initial 2.1 to 4.7/4.8 as the ant-acid mixture was added. It really works!

Specifications

Specifications for the electrode