February 1 and February 8 2011
Aim and Objective:
The aim of this experiment was to determine the pH level of an unknown HCl solution. While doing so, we would also be receiving a good and fundamental understanding of how to use modern lab equipment to determine the chemical and physical properties of water bodies.
Make sure safety gear is always on and equipment is always clean.
Part 1- Direct Analysis by pH Test Kit
We grab a 50ml beaker and obtain a sample of unknown HCl as said to do in the procedure section in page 3. A pH test kit was provided to us were we had to find the pH level of the HCl by adding a few drops of a chemical into our solution. After a few seconds we would compare the color that the HCl turned into against a strip provided to us in the kit. This procedure was only performed once and came to the final result that our unknown HCl had the pH level of 4. Once we were done with all the equipment we would clean it all off with distilled water three times.
Part 2-Direct Analysis by pH Meter
We grab a 50mL beaker that obtains samples of the unknown HCl solution and two beakers one with pH4 and the other with pH7 buffers needed to adjust the meter and electrode. Remember to clearly mark all of the beakers in order to not get the solutions mixed up. Obtain a Hanna 8014 pH meter and electrode like said to do so on page 4 under procedures. If a protective cap is over the end of the electrode REMEMBER to remove it. Okay so before the pH meter can be used it has to be calibrated. The way to calibrate it is by placing the 50mL beaker of pH7 onto the magnetic stirrer, add a stir bar and start to gently stir. Using the stand and clamp insert the thermometer into the center of the buffer solution making sure that the bulb is completely in the solution and not touching any part of the beaker. Carefully remove the cap from the electrode and rinse with distilled water. Using another clamp carefully clamp the electrode so that the bulb is once again completely along the side of the thermometer but not touching anything. Once that is done we have to turn the pH meter dial to Celsius. Wait a few minutes for reading to stabilize and then use a tiny screwdriver to adjust the meter to read exactly the same temperature as the thermometer. Now without disturbing the previous setup turn the dial to pH and use the screwdriver to adjust meter to exactly 7.00. Once that is all done we grab anything the pH 7 touched and rinse it off with distilled water and follow the exact same steps for the pH4 as said to do so in page 5. Finally for the measurement of pH we remove both the electrode and stir bar and rinse with distilled water. Now we place a 50mL beaker of unknown HCl solution onto the magnetic stirrer add the stir bar, insert the electrode as before and begin gentle stirring. Wait a few minutes and record the stabilized reading. Remember to not wait long because pH meter readings drift over time. Repeat process 3 times and record readings and average. Now that all is done we wash it all with distilled water and move on to the next step.
Part 3: Direct Analysis by Water Quality Monitor
We got to see and hear about the modern equipment being used in today’s science. Dr. Clark brought out the pHOX 901 Water Quality Monitor and Data logger. This fascinating instrument simultaneously measures turbidity, conductivity, Temperature, Salinity, pH, Dissolved Oxygen, Ammonia and the Ammonium ion concentration. Remember if the pH level is too low the sensor array can’t read it. Look at the technology and learn its use.
Part 4: Chemical Titration
*Remember when recording data that NaOH=1.00 x 10-1
In this final stage what the overall point of this step is to determine the molarity of the unknown HCl solution and then convert it into pH. On page 8 under procedures is the exact steps on how to complete this experiment. In this final process we used the...