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1.6

Major VersionM

by Procheta Mallik

Introduction

Matter of all forms expand and contract on heating or cooling respectively. This principle is used in thermometers where the expansion of liquid mercury helps in determining temperature. In this tactivity we will explore a non-mercury based thermometer, a test tube carrying propanol with a capillary tube attached.

Video Overview

    • Be mindful while using scissors and the test tube.

    • Careful while twining the binding wire; be careful of its pointy ends

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  1. Take a wooden spoon and make two holes within the concave part of the spoon, about 1.5 cm apart.
    • Take a wooden spoon and make two holes within the concave part of the spoon, about 1.5 cm apart.

    • Be gentle in making the holes otherwise you will end up breaking the spoon while twisting the scissors.

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    • Take the binding wire of length about 30 cm and bend it at the centre .

    • Press the edge of the binding wire with a pair of cutting pliers near where the loop is formed.

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    • Now pass the ends of the double-folded binding wire through the two holes to form a loop.

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    • Bend the sharp edges and make a small loop.

    • Make small hooked ends by bending both the thin wires as shown in the picture.

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    • After the test tube is correctly placed inside the loop, start twisting the loose ends of wire together.

    • The binding wire has to be tight enough so that the test tube is held properly.

    • Note that the test tube will get a bit heavier when there is stuff in it; so it's important that the twining is firm enough to hold it even then.

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    • Too many twists in the binding wire, which may lead to breakage of binding wire.

    • Test tube falling through. Wire not twisted tight enough.

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    • Fill some water and check if the test tube holder can bear the weight.

    • In the 13 ml test tube you have, how many grams of water can you fill? What about mercury?

    • Try making the test tube holder using an ice cream stick instead of the spoon.

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    • If hot water comes in contact with skin, it can lead to mild to serious burns depending on the temperature of water. Adult supervision recommended while heating water and handling hot water.

    • The capillary tube is very delicate. If high force is applied or force applied at inappropriate points, it can break easily.

    • Please do not ingest any material

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    • Place the test tube with its opening on the foam piece and press them together such that there’s an impression on the foam piece

    • Take a scissor and cut around the impression on the foam piece

      • Make sure to only cut around the impression and not inside the enclosed circle

    • Insert about 3/4th of the foam piece into the test tube opening. This will act like a cork

    Suchitha you seem to have changed this guide since I last edited it. You need to change the pictures to the materials we are providing, i.e. dropper bottle with the colouring agent already inside. Didn’t realise this guide was so different compared to what we have actually sent as materials

    Procheta Mallik - Reply

    Also, please don’t change the text; I’m doing that

    Procheta Mallik - Reply

    • Place one end of the capillary tube on the cork piece and turn it clockwise or anti-clockwise inside the foam piece gently.

      • Hold the capillary as close as possible to the end which you are inserting in the foam. This will minimize the chances of breaking it.

    • Keep turning the capillary tube in until it comes out of the other side of the foam piece. You need around 2 cm of the capillary below the foam piece.

      • Turn gently and try not to break the capillary tube with too much force

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    • Remove the foam piece with the capillary tube in it from the test tube.

    • Fill propanol into the test tube upto 2 cm from the opening of the test tube.

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    • Add a few drops of colourant to the propanol. You may use coloured ink or dyes or stains like safranin.

    • Block the test tube with thumb and shake it well to mix the color.

    • Close the test tube with the foam piece

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    • Dip the thermometer in hot water. What do you observe?

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    • Insert the test tube in hot water, keep it for a while and then drop it in cold water. What do you observe?

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    • Propanol will overflow out of the capillary tube if the water is too hot; this is normal

    • If cut towards the inner edge of the impression on the foam, the test tube might not get sealed well. You might not be able to witness the capillary action well.

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    • What do you observe happens to the propanol in the capillary tube when you insert the test tube in hot water? Try and measure the level of propanol in the capillary tube once you insert it in hot water. Also, measure the time it takes for the propanol to rise or fall in the capillary tube.

    • What happens when you keep the test tube in normal water after keeping in hot water? Measure the level of the propanol in the capillary tube in the hot water and when switched to cold water. Also, measure the time it takes for the propanol to rise or fall in the above situations.

    • What do you observe when you keep the thermometer in normal water for a bit and then switch it to hot water? Make measurements of the height of the propanol in the capillary at both times.

    • Measure the height of propanol in the capillary tube and the time it takes for it to rise or fall. How different are these measurements in comparison to the values obtained in the hot water?

    • What do you observe happens to the propanol in the capillary when you directly insert the test tube in cold water and keep it for a longer time? Try observing the bottom of the capillary tube which is immersed in the test tube. What happens at that point?

    • What do you observe when you insert the test tube in any sort of water and remove it and hold it? Does the propanol come back to its original position? What do you observe if you leave the test tube outside for a while? Does the propanol rise or fall?

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    • Remove the foam piece with the capillary from the test tube

    • Remove the capillary tube from the foam piece

    • Insert the thin bendable plastic capillary tube into the foam piece

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    • Re-insert the foam piece with the plastic capillary into the test tube with propanol

    • Take another empty test tube and insert the opening of the capillary tube into it

    • Place the propanol filled test tube into hot water and let the other test tube collect the expanding propanol

      • Measure the amount of propanol that is displaced into the empty test tube for water at different temperatures. What do you observe looking at these values?

      • If no propanol is displaced then please check the temperature of the water. It might be too low

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Finish Line

Suchitha Vishwa

Member since: 05/02/2017

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