Set up of a non-visual lab
Activity

Acid-Base Titration Using Nonvisual Tools

Video demonstration of performing an Acid-Base Titration Nonvisually with the Talking LabQuest 2, Titration ColorCam App and the Vernier pH Sensor and Drop Counter

By Caroline Karbowski, Research Assistant: Department of Biological Chemistry and Pharmacology at Ohio State University

Caroline Karbowski demonstrates how she uses the Sci-Voice Talking LabQuest 2 from Independence Science, the Titration ColorCam App on an Android phone, and the Vernier pH Sensor and Drop Counter to record and analyze volume and pH data.

Closed captions are edited and include Caroline and the LabQuest’s audio. Caroline learned these nonvisual lab skills from working with blind scientists. If you would like to learn more about nonvisual skills and blindness, check out blindness organizations such as the National Federation of the Blind, the American Foundation for the Blind, and the American Council of the Blind. To learn more about accessible lab techniques, check out Independence Science: https://independencescience.com/

Transcript

Title: Performing an Acid-Base Titration Non-Visually with the Talking LabQuest 2, Titration Color Cam App, and the Vernier pH Sensor and Drop Counter

On a chemistry lab bench a titration is set up. A buret with the stop clock is filled with 0.1 formal sodium hydroxide and is attached to a ring stand. Beneath is a magnetic stir plate with a 250 milliliter beaker with .0943 grams of potassium acid phthalate dissolved in about 50 milliliters of water. A magnetic stir bar spins inside the beaker. A Vernier drop counter is connected to another ring stand and is above the beaker. The tip of the buret is right above the drop counter, so when drops fall from the buret the sensor will see it and count the drop.

The drop counter has an additional hole to hold the Vernier go direct pH sensor. The readout for both of these sensors appear on the Talking LabQuest 2 made by Vernier in conjunction with Independence Science. The screen display is in high contrast mode showing a black screen with yellow font. The drop counter is connected with the cable and the pH sensor is connected via Bluetooth to the LabQuest.

There’s also a USB keyboard plugged into the LabQuest. An Android phone on a bendy tripod has a Titration Color Cam App open. It uses the phone camera to analyze the color of the liquid in the flask. It will beep and vibrate when a color change occurs, so that way a blind or colorblind person will know when the end point of the titration is reached. Right now the app is on the phenolphthalein indicator mode, so when the solution turns pink the phone will beep and vibrate. Right now the solution is just clear. Two drops of phenolphthalein indicator were added three more times.

Caroline opens the stop clock to allow drops of sodium hydroxide to deposit into the acid solution. The first few drops aren’t counted by the drop counter because it wasn’t lined up correctly. She adjusts the drop counter so the drops are actually being sensed by the drop counter.

Adding drops into the acid solution
Adding drops into the acid solution

The starting pH is 3.96 and the starting volume of base added is 0.000 milliliters. As drops are continuously added the pH rises and the volume of base added rises.

LABQUEST VOICE reads various measurements.

The phone using the titration color cam app started beeping and vibrating when the solution turned light pink and now it is turning a dark pink.

Solution in beaker turns dark pink
Solution in beaker turns dark pink.

LABQUEST VOICE reads various measurements.

Analyzing Data

Now the view is focused on the LabQuest screen showing a graph.

Screenshot of LabQuest2 data
LabQuest screen showing a graph

It’s a sigmoidal curve where the volume is on the x-axis and the pH is on the y-axis as the pH increases. You’ll hear in the sonification that the pitch goes from low to high because the curve is going from a small value to a larger value.

Also as Caroline navigates the file software, she’s using a QWERTY keyboard and you’ll hear the file options that she’s selecting.

LABQUEST VOICE reads file options.

Now Caroline is going to go to the plot details where you can hear more statistical values and then she’s going to save the file onto a flash drive to then look at the data on a computer.

LABQUEST VOICE

Note you can only plug in one USB item into the LabQuest at a time. Right now the QWERTY keyboard is plugged in, so Caroline has to unplug the keyboard in order to put the flash drive in and due to this, she then had to use the touch screen interface in order to save the file. If you wanted to be able to do this completely non-visually you could get a USB splitter that goes into the LabQuest USB port and then you’d have multiple holes to plug in both the keyboard and the flash drive.

LABQUEST VOICE

She types the word “test” with her finger on the touch screen.

LABQUEST VOICE

She unplugs the flash drive and replugs in the USB keyboard.

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