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3.7

Major VersionM

by Raghottam Joshi

Introduction

Chemical reactions often create a change in colour. Here, we use one such reaction to also measure our rate of respiration and metabolism.

Video Overview

    • Do not ingest any material.

    • Do not suck from the straw by mistake; only blow, and blow gently!

    • Scissors/Cutters have sharp functional edges. Contact with body may harm.

  1. Make a mark on a fat straw at 1 cm from one end. Pinch the straw end (from where you measured) and tape it as shown in the picture. The pinching is done to avoid the powder sticking to the tape.
    • Make a mark on a fat straw at 1 cm from one end.

    • Pinch the straw end (from where you measured) and tape it as shown in the picture.

    • The pinching is done to avoid the powder sticking to the tape.

    • Make sure that there is no gap left while sealing the insulation tape.

  2. The given test tube has a capacity of about 6 ml. Add 17 test tubes full of water to a plastic bottle/container. This volume of water will be equal to approximately 102 ml.
    • The given test tube has a capacity of about 6 ml.

    • Add 17 test tubes full of water to a plastic bottle/container.

    • This volume of water will be equal to approximately 102 ml.

  3. Take one measure of 0.2 g of the calcium oxide (lime). Add it to the 102 ml of water and stir well. Use the 102 ml of water we prepared in the previous step.
    • Take one measure of 0.2 g of the calcium oxide (lime).

    • Add it to the 102 ml of water and stir well.

    • Use the 102 ml of water we prepared in the previous step.

  4. Fold the filter paper twice. The first fold should give you a semi-circle shape, and the second fold gives a quarter circle. Note that the second fold will give you four flaps as you try to open it to get a cone. Note that the second fold will give you four flaps as you try to open it to get a cone.
    • Fold the filter paper twice. The first fold should give you a semi-circle shape, and the second fold gives a quarter circle.

    • Note that the second fold will give you four flaps as you try to open it to get a cone.

  5. Separate the flaps such that you get three flaps on one side and one flap on the other side. Tape the 3-flap side together to get a cone. This cone itself is your funnel.
    • Separate the flaps such that you get three flaps on one side and one flap on the other side.

    • Tape the 3-flap side together to get a cone.

    • This cone itself is your funnel.

  6. cut the bottle in half using a cutter/scissors. Remove the bottle cap and place the upper half of the bottle inverted over the lower part. This acts like a funnel. Place a filter paper in the upper part of the bottle.
    • cut the bottle in half using a cutter/scissors.

    • Remove the bottle cap and place the upper half of the bottle inverted over the lower part. This acts like a funnel.

    • Place a filter paper in the upper part of the bottle.

  7. Transfer the calcium hydroxide solution into the bottle through your bottle-funnel. Wait for all the liquid to filter down. Dip a red litmus paper into it and observe if there's a colour change.
    • Transfer the calcium hydroxide solution into the bottle through your bottle-funnel.

    • Wait for all the liquid to filter down.

    • Dip a red litmus paper into it and observe if there's a colour change.

  8. Transfer 5 ml of the filtered calcium hydroxide solution into a plastic container with the help of a dropper. Add 5 drops of Bromothymol blue indicator. Insert a straw into the plastic container and start to blow. Count and record the number of exhalations till the solution turns pale green.
    • Transfer 5 ml of the filtered calcium hydroxide solution into a plastic container with the help of a dropper.

    • Add 5 drops of Bromothymol blue indicator.

    • Insert a straw into the plastic container and start to blow. Count and record the number of exhalations till the solution turns pale green.

    • Do not take deep breath. Breathe as you normally do.

  9. Continue blowing till the colour of the liquid changes to a shade of green. Dip a red litmus paper into the solution and observe if the litmus paper changes its colour.
    • Continue blowing till the colour of the liquid changes to a shade of green.

    • Dip a red litmus paper into the solution and observe if the litmus paper changes its colour.

  10. This process is reusable : Add 1 ml of filtered Calcium Hydroxide solution  into the reactant solution. Use the same straw and start to blow. Count and record the number of exhalations till the solution turns pale green. This process is reusable : Add 1 ml of filtered Calcium Hydroxide solution  into the reactant solution. Use the same straw and start to blow. Count and record the number of exhalations till the solution turns pale green. This process is reusable : Add 1 ml of filtered Calcium Hydroxide solution  into the reactant solution. Use the same straw and start to blow. Count and record the number of exhalations till the solution turns pale green.
    • This process is reusable : Add 1 ml of filtered Calcium Hydroxide solution into the reactant solution. Use the same straw and start to blow. Count and record the number of exhalations till the solution turns pale green.

    • Patiently blow until the colour changes.

    • If it is taking too many blows it is possible that, Lime is not mixed well with water.

    • If it is taking too many blows it is also possible that, not enough indicator is used.

  11. Variation 1 : Injecting carbon dioxide into the  calcium hydroxide (lime solution). Variation 2 : Make the barium hydroxide solution and blow air into it with the help of straw. Variation 3 : Reaction with turmeric solution.
    • Variation 1 : Injecting carbon dioxide into the calcium hydroxide (lime solution).

    • Variation 2 : Make the barium hydroxide solution and blow air into it with the help of straw.

    • Variation 3 : Reaction with turmeric solution.

    • Variation 4 : Reaction with sodium hydroxide solution.

    • To learn more about the variations, DIY Respirometer (Variations)

Finish Line

Vishal Bhatt

Member since: 04/26/2017

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