Written By: Manikandan S...— Step 9 - Extension for Scale I Take two 15 cm ice cream sticks. Take one of the ice cream sticks, measure and mark about 5 cm on the stick. Make an initial

DIY ThermometerMake a non-mercury thermometer using a thin straw

Written By: Manikandan S

DIY Thermometer 2020-05-17[minor]2.1Release:Guide ID: 286 -

This document was generated on 2020-05-17 01:41:55 AM (MST).

© 2020 Page 1 of 15

INTRODUCTION

Matter of all forms, expand and contract, on heating or cooling respectively. This principle is used inthermometers, where the expansion of liquid mercury helps in determining the temperature. In thisTACtivity we will make and explore a non-mercury based thermometer using a test tube filled withpropanol and a straw acting as the capillary tube.

TOOLS:Scissors (1)DIY Test Tube Stand and Holder (1)Glue (1)Paper Cutter (1)Safety Pin (1)Ruler (1)Dropper (1)Sketch Pen or Marker (1)Induction or Gas Stove (1)Steel Vessel with Water (1)

PARTS:Test Tube (2)Safranin (1)

<1 mlThin Straw (2)

4 mmFoam Piece (2)

2x2Propanol (1)

30mlBeeswax (1)

1 gmIce Cream Stick (2)

15 cmDIY Measuring Scale Template (1)

20 cm



© 2020 Page 2 of 15

— Precautions

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

Please do not ingest any material.

Handle scissors with extreme care.

— Step 1 - Test Tube Stand

To make this TACtivity, we will needa 'DIY Test Tube Stand and Holder'.

To make this TACtivity, go to 'DIYTest Tube Stand and Holder'.



© 2020 Page 3 of 15

https://www.tactivity.in/Guide/DIY+Test+Tube+Stand/516

— Step 2 - Making the Cork

Place the open end of a test tube on the foam piece and press them together, such that there’s acircular impression on the foam piece.

Take the scissors and cut around the impression on the foam piece.

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

— Step 3 - Making a Hole in the Cork

Use a safety pin to make a pilot hole in the centre of the cork.

With the help of scissors, widen the hole such that the straw snugly fits into it.

Make sure that the hole is exactly at the centre, to avoid tearing of the foam.



© 2020 Page 4 of 15

— Step 4 - Inserting the Straw

Before inserting the straw into the hole, pinch the tip of the straw for it to easily fit into the hole.

Insert the straw into the hole made on the foam.

Hold the straw end which you will be inserting in the foam, as close as possible, to the hole in thefoam. This will minimise the chances of breaking it.

While inserting the straw, make sure that only the tip of the straw protrudes, from the other end ofthe foam.

— Step 5 - Marking the Bulb

An empty test tube will be used as our thermometer bulb.

Mark a line with a marker at 1.5 cm, measured from the open end of the test tube.



© 2020 Page 5 of 15

— Step 6 - Filling the Bulb

With the help of a dropper, add 5 to 6 drops of safranin or a similar colourant/dye, into the testtube.

Now, gradually add propanol into the test tube till, propanol reaches the mark on the test tube.

Slightly shake the test tube, while adding propanol, so that the colourant uniformly mixes into it.



© 2020 Page 6 of 15

— Step 7 - Sealing the Bulb I

Take the foam piece and straw assembly; push it into the test tube.

Push the foam gradually removing all the remaining air present inside the test tube.

Fold the straw and gradually push the straw about 5 cm into the test tube, measuring from its openend.



© 2020 Page 7 of 15

— Step 8 - Sealing the Bulb II

As we continue pushing the straw and foam assembly, we will notice a small rise in the level ofpropanol in the straw.

Once there is a small increase in the level of propanol, stop pushing the straw and foam assembly.

Seal the open end of the bulb/test tube, by applying glue, to make the bulb of the thermometer airtight.

Our thermometer is almost ready!

— Step 9 - Extension for Scale I

Take two 15 cm ice cream sticks.

Take one of the ice cream sticks, measure and mark about 5 cm on the stick.

Make an initial mark with the help of a paper cutter and then fold the ice cream stick to break it intotwo pieces.



© 2020 Page 8 of 15

— Step 10 - Extension for Scale II

Place the uncut ice cream stick and one of the cut ice cream stick pieces adjacent to each other,such that the rounded edges are in contact.

Apply glue to the remaining part of the cut ice cream stick and place it over the two sticks, whichare placed adjacent to each other.

Now, this will be the extension scale.

— Step 11 - Pasting I

Glue the DIY Scale Template on to the scale extension.

Our calibrating scale is now ready.



© 2020 Page 9 of 15

— Step 12 - Pasting II

Adjust the extension scale on the test tube, such that zero on the extension scale coincides withthe top of the foam.

Mark the position of the extension scale on the test tube stand.

Now, apply glue on the ice cream stick of the test tube holder and paste the extension scale on it.

— Step 13 - Measuring Room Temperature

When the thermometer is undisturbed, we can see some amount of propanol present in the straw.

Now, take a marker and mark the level of propanol in the straw, on the extension scale.

This mark indicates the room temperature reading on the thermometer.



© 2020 Page 10 of 15

— Step 14 - Temperature of Palms

Rub your hands to generate some heat and then hold the thermometer in your hands firmly for atleast 3 minutes.

You will notice a rise in the level of propanol.

Insert the thermometer back into the stand and mark the point equal to the rise in level of propanolin the straw.

This point indicates your body temperature, which is around 35℃ to 37℃.



© 2020 Page 11 of 15

— Step 15 - Melting Beeswax I

Take 1 gm of beeswax in another test tube, now heat the beeswax using a water bath kept on aconstant heat source.

Check the melting process of beeswax, as this is crucial in determining the next reading.

Once the beeswax has completely melted, remove the test tube and water bath from the heatsource.

Immediately keep the thermometer in the hot water bath.

— Step 16 - Melting Beeswax II

As the thermometer is dipped in the hot water bath, level of propanol in the straw rises gradually.

It continues to rise for about 5 minutes. Now, remove the thermometer from the hot water bath andimmediately mark the propanol level on the extension scale.

This mark indicates the temperature of molten beeswax which is about 62℃.



© 2020 Page 12 of 15

— Step 17 - Thermometer Calibration

Measure the difference in the propanol levels between 'Body Temperature' and 'Molten BeeswaxTemperature'.

The following formula will give us the change in temperature, for a change in the level of propanolby 1 cm. (Temperature of molten beeswax - Average human body temperature)/(Difference inpropanol level for the two)

Say, every 1 cm increase in propanol gives a 3.5℃ increase in temperature. Considering this rate,mark the full length of the plastic straw with temperature values.

We now have a fully functioning thermometer.



© 2020 Page 13 of 15

— Play!

Insert the bulb of the thermometer into different test objects and note their temperatures.

Place the thermometer inside soil or sand and after 7 minutes, observe the temperature of theground.

Keep the thermometer for about 2 minutes inside a container containing boiling water and thenobserve the temperature (usually propanol over flows from the straw since its temperature is out ofscale for the thermometer we have created).

— Troubleshooting

Propanol overflows from the straw - 1) Temperature of test object exceeds the thermometer limit.2) Height of the straw outside the test tube is small.

If the inner section/edge of the circular impression is cut on the foam, then the test tube might notget sealed well. The propanol may not rise in the straw.

Rise in propanol level is different for the same test object -1) There is an air bubble present insidethe bulb of the thermometer, hence remove the air bubble.

Propanol level in the straw is not rising or drops frequently - 1) Outside air might be entering intothe bulb; reseal the bulb and make sure it is airtight.



© 2020 Page 14 of 15

— Suggested Variations

Replace the thin straw by capillary tube.

Make DIY Thermometer using DIY Translucent Straw made from the butter paper

To lean more about the variations, go to DIY Thermometer (Variations).



© 2020 Page 15 of 15

https://www.tactivity.in/Guide/DIY+Thermometer+(Variations)/558

Documents

Written By: Manikandan S...— Step 9 - Extension for Scale I Take two 15 cm ice cream sticks. Take one of the ice cream sticks, measure and mark about 5 cm on the stick. Make an initial