This is an instructional video on how to prepare buffers. The following are all the materials, chemicals, and instruments used for this experiment. Here we prepared 250 milliliters of a 1 molar Tris HCl buffer with pH of 7.5.

Begin by turning on the scale and placing a weighing boat on the pan.

Press TARE to readjust the instrument and weigh 30.29 grams of Tris powder. The amount of the chemical needed to prepare the buffer should be calculated prior to measurements. It can be done so by using the formula mass equals final concentration multiplied by the total volume of the buffer and molarity of the chemical.

Label a clean beaker with the name of the buffer to be prepared including its concentration and pH.

Transfer the Tris powder and a magnetic rod into the beaker and pour around 200 milliliters of distilled water.

Place the beaker on a magnetic stirrer to assist in dissolving the buffer.

Allow the buffer to fully dissolve and after it has done so, prepare the pH meter by removing the electrode cap, loosening the electrode wheel, and washing the electrode with distilled water and a clean beaker to collect the waste.

Remove the excess liquid with a paper towel and immerse the electrode into the buffer. Continuous stirring of the buffer allows for equal distribution during measurements.

To adjust the pH, use an appropriate acid or base. This is very important since it would impact the results of your experiment. Here we want to decrease the pH from 11 to 7.5, so one molar hydrochloric acid was added drop-wise.

Immediately after adding the acid, a decrease in pH is observed.

After achieving the desired pH, remove the electrode, wash as described before, and place the cap back on for storing. Don't forget to tighten the electrode wheel and turn off the instrument.

For the final volume adjustment, the buffer is transferred to a volumetric flask using a glass funnel.

When high precision is required, volumetric flasks are often chosen for volume adjustments over other equipment such as graduated cylinders.

Wash the beaker to remove any remaining buffer.

For the final volume adjustment, remove the glass funnel and add distilled water drop-wise until a meniscus is visible at the calibrated mark on the neck of the flask.

Place the lid on and mix the buffer by inverting the flask.

For storing, transfer the buffer into a clean bottle. Remember to always label the bottle with information such as the name of the

buffer, concentration, pH, your name or initials, and the date when it was made. Depending on the buffer, the storing conditions differ in terms of temperature and, for example, if it can be autoclaved for sterilization. After transferring, tighten the lid of the bottle and this way you have managed to successfully prepare a buffer.