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1.5

Minor Versionm

by Procheta Mallik

Introduction

Commercially, sodium hydroxide is made through the electrolysis of a brine solution. Here, we do the same, albeit on a much smaller scale, to make your own sodium hydroxide, the quintessential base, with Hydrogen and Chlorine as byproducts.

    • Exercise caution while handling scissors/cutters or any sharp object.

    • Do not ingest any of the chemicals

    • Excessive exposure to chlorine gas may lead to nausea, vomiting, headache, etc. While smelling chlorine, inhale it just enough to test it's presence.

    • Wash the hands properly after using any chemicals.

  1. Cut a 4 cm piece from a fat straw. Seal one end of the cut straw with the tape, as shown. Seal one end of the cut straw with the tape, as shown.
    • Cut a 4 cm piece from a fat straw.

    • Seal one end of the cut straw with the tape, as shown.

  2. Completely seal one end of the straw; this is your `measuring cup'. Your measuring cup will hold 2.5 g to 2.75 g of salt in it. Your measuring cup will hold 2.5 g to 2.75 g of salt in it.
    • Completely seal one end of the straw; this is your `measuring cup'.

    • Your measuring cup will hold 2.5 g to 2.75 g of salt in it.

  3. Add two cups of common salt (NaCl) in the measuring cup and add it to a cut bottle. Add around 70 ml of water to the NaCl. You may use the 30 ml bottles provided to estimate the amount of water you add. Use markings on the container to measure the quantity of water to take
    • Add two cups of common salt (NaCl) in the measuring cup and add it to a cut bottle.

    • Add around 70 ml of water to the NaCl. You may use the 30 ml bottles provided to estimate the amount of water you add.

    • Use markings on the container to measure the quantity of water to take

    • Stir the contents to make NaCl Solution.

  4. Wash the containers thoroughly with water before starting the process. Take a 30 ml container and mark 2 cm from the bottom. Make a hole at the mark using scissors.  Make the hole big enough so that a straw can snugly fit inside it.
    • Wash the containers thoroughly with water before starting the process.

    • Take a 30 ml container and mark 2 cm from the bottom.

    • Make a hole at the mark using scissors. Make the hole big enough so that a straw can snugly fit inside it.

    • Repeat the same with the other container.

  5. Take a stiff straw (or thin rubber/plastic pipe) and mark 4 cm from one end of it. Cut the straw at the marking. Insert a cotton ball of pea size into the cut straw.
    • Take a stiff straw (or thin rubber/plastic pipe) and mark 4 cm from one end of it.

    • Cut the straw at the marking.

    • Insert a cotton ball of pea size into the cut straw.

  6. Insert the straw into the container. Glue the straw to the container. Insert and glue the other end of the straw to the hole of the other container.
    • Insert the straw into the container.

    • Glue the straw to the container.

    • Insert and glue the other end of the straw to the hole of the other container.

  7. Add the prepared NaCl solution to either of the containers. Note that the level in the containers is automatically the same! Your apparatus is now set up, as shown. Using the dropper add few drops of Bromothymol blue indicator to both the containers.
    • Add the prepared NaCl solution to either of the containers. Note that the level in the containers is automatically the same!

    • Your apparatus is now set up, as shown.

    • Using the dropper add few drops of Bromothymol blue indicator to both the containers.

  8. Go to DIY Battery Holder to make one of your own and use it here. Connect the negative terminal of the battery to the iron nail. Make sure to wash the iron nail initially  to remove the greasy layer from it.
    • Go to DIY Battery Holder to make one of your own and use it here.

    • Connect the negative terminal of the battery to the iron nail.

    • Make sure to wash the iron nail initially to remove the greasy layer from it.

    • Connect positive terminal of the battery to a pencil lead (graphite).

    • Your electrodes' set up looks like this.

  9. Now insert the iron nail in one container and the graphite rod in the other. Observe the color change in both the containers after some time. Observe the color change in both the containers after some time.
    • Now insert the iron nail in one container and the graphite rod in the other.

    • Observe the color change in both the containers after some time.

  10. Once the color in the container with iron nail turns blue, dip the red litmus and observe the color change of the litmus paper. Dip a pH paper into the container with the iron and observe and note down the pH based on the colour of the pH paper
    • Once the color in the container with iron nail turns blue, dip the red litmus and observe the color change of the litmus paper.

    • Dip a pH paper into the container with the iron and observe and note down the pH based on the colour of the pH paper

    • Liquid coming out of the container(s) after inserting the straw.

    • While making hole in the container please verify repeatedly to check the size of the hole with the straw (or pipe).

    • Electrolysis not started, change in colour not happening nor bubbles emanating.

    • Check for the electrical connections.

    • Change in red litmus and pH paper colour not visible.

    • Wait for few more minutes to check for the colour change.

  11. Note down the time at which electrolysis started and at what time solution at iron electrode turn blue completely. Record this time in the first column of observation table.
    • Note down the time at which electrolysis started and at what time solution at iron electrode turn blue completely.

    • Record this time in the first column of observation table.

    • Using the pH paper find out the pH of NaOH solution prepared at Iron electrode using the pH scale chart.

    • Repeat it after every 15 mins and record your findings in observation table.

  12. Vary the concentrations of NaCl and compare the time taken for colour change. Replace iron nail electrode by graphite rod. Place two iron nails and two graphite rods instead of one.
    • Vary the concentrations of NaCl and compare the time taken for colour change.

    • Replace iron nail electrode by graphite rod.

    • Place two iron nails and two graphite rods instead of one.

    • Replace two AA cells by one 9V battery.

Finish Line

Attached Documents

Vishal Bhatt

Member since: 04/26/2017

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