reaction

Next, start the reaction by adding the sodium borohydride reagent.

As the reaction proceeds, track it using TLC and write down your qualitative observations in your lab notebook.

The photo shows a piece of weighing paper on a laboratory scale. There is a small pile of white crystals on the paper. The screen on the scale reads “0.0150 g.”

The video shows the bottom of a graduated test tube, in which there is approximately 0.50 mL of cloudy white solution. A drizzle of white solids are added to the solution from above, at which time a timer appears at the bottom of the screen and begins counting second upward from zero. At second 00:05, a metal spatula appears and is used to scrape down the sides of the test tube and swirl the mixture in the bottom. The spatula is left resting in the tube until second 00:25, and which time it is used to swirl the mixture again and removed. At 00:30, the timer begins to speed up, indicating the video is being played at an accelerated pace. During this sped up footage, we see bubbling at the surface of the opaque white solution. When the timer reads 01:11, pipette is used to suction the solution from the bottle of the tube and rinse down the sides of the test tube, where some solids have become stuck. We see during this time that the solution has a grainy quality, with a high volume of white solids suspended in it. The bubbling continues at the solution’s surface. At minute 02:20, the metal spatula reappears and swirls the solution again, after which a thin glass tube is dipped gently into the solution. Next we see two thin layer chromatography plates with lane markings “0,” “2,” and “5” (on the left plate) and “10,” “12,” and “15” (on the right plate). There is a small wet circle on the “2” origin line, indicating that it has just been spotted with a rapidly evaporating material. We then return to the view of the graduated test tube for more accelerated video of the gently bubbling white mixture. At minute 05:05, the spatula twirls the mixture again and another thin glass tube is dipped into the mixture. We see the thin layer chromatography plates again, this time with a wet spot in the “5” lane. When we return to the test tube, we see that a white fog or crust has begun to adhere to the sides of the test tube, farther up the walls than the level of the liquid solution. If bubbling is continuing, it is invisible behind the white fog. At minute 10:45, the mixture is swirled with the spatula and sampled with the thin glass tube again. We see the thin layer chromatography plates again, this time with a wet spot in the “10” lane. The mixture is swirled with the spatula and sampled with the thin glass tube again at 12:14, although this process is barely visible through the white solids adhered up and down the walls of the test tube at this time. We then see a wet spot in the “12” lane of the thin layer chromatography plates. Finally, the opaque white contents of the test tube are swirled and sampled one last time with the glass tube at 15:28. The video ends with a final view of the thin layer chromatography plates, which now show a wet spot in the “15” lane.

Analyze the TLC plates.

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