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2.6

Minor Versionm

by Manikandan S

Introduction

We test and measure the solubility of salt in water, at different temperatures.

Video Overview

    • Adult supervision is recommended while heating.

  1. To make the DIY Test Tube Stand, go to DIY Test Tube Stand.
  2. Measure 1.4 cm from one end of a straw and make a mark with a sketch pen. Cut the straw at the mark made. This straw piece will measure 0.5 g of common salt. Pinch one end of the straw and tape it, as shown in the picture.
    • Measure 1.4 cm from one end of a straw and make a mark with a sketch pen.

    • Cut the straw at the mark made. This straw piece will measure 0.5 g of common salt.

    • Pinch one end of the straw and tape it, as shown in the picture.

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

    • Making the measuring cup is not necessary if you have access to a weighing scale.

  3. Fill the test tube with 10 ml of water, using a dropper. Fill the test tube with 10 ml of water, using a dropper. Fill the test tube with 10 ml of water, using a dropper.
    • Fill the test tube with 10 ml of water, using a dropper.

  4. Measure 0.5 g of common salt. 1 full unit of the straw measuring cup you just made would contain 0.5 g of common salt. Transfer the salt into the test tube. Stir the solution, using a wooden skewer, until the salt dissolves completely.
    • Measure 0.5 g of common salt. 1 full unit of the straw measuring cup you just made would contain 0.5 g of common salt.

    • Transfer the salt into the test tube.

    • Stir the solution, using a wooden skewer, until the salt dissolves completely.

  5. Add 7 measuring cups of salt to the test tube. This would be equal to about 3.5 g of common salt. Stir the solution, using the skewer, until the salt dissolves completely and the solution becomes saturated, i.e. no further salt can be dissolved in it.
    • Add 7 measuring cups of salt to the test tube.

    • This would be equal to about 3.5 g of common salt.

    • Stir the solution, using the skewer, until the salt dissolves completely and the solution becomes saturated, i.e. no further salt can be dissolved in it.

  6. Once the solution becomes saturated, add one more cup of salt, using the measuring cup. Stir the contents thoroughly. If the salt doesn't dissolve any further, you have a saturated solution. Take the sketch pen and mark the level of salt in the test tube, as shown in the picture.
    • Once the solution becomes saturated, add one more cup of salt, using the measuring cup.

    • Stir the contents thoroughly. If the salt doesn't dissolve any further, you have a saturated solution.

    • Take the sketch pen and mark the level of salt in the test tube, as shown in the picture.

  7. Heat the solution over a candle  flame for 2-3 min, as shown in the picture. Hold the test tube in an inclined position while heating. After the test tube is removed from the heat, mark the level of salt in the test tube.
    • Heat the solution over a candle flame for 2-3 min, as shown in the picture.

    • Hold the test tube in an inclined position while heating.

    • After the test tube is removed from the heat, mark the level of salt in the test tube.

    • Note down the change in the level of salt before and after heating.

  8. Once the salt solution starts cooling down, the additional salt that was dissolved after heating recrystallises.
    • Once the salt solution starts cooling down, the additional salt that was dissolved after heating recrystallises.

  9. Wash the test tube and place it in the test tube stand, as shown. Fill the test tube with 10 ml of acetone. Add two full units of common salt to the test tube, using the measuring cup.
    • Wash the test tube and place it in the test tube stand, as shown.

    • Fill the test tube with 10 ml of acetone.

    • Add two full units of common salt to the test tube, using the measuring cup.

  10. Using a sketch pen / marker, mark the level of salt in the test tube. Using a wooden skewer, stir the contents well for two minutes. Observe the change in the level of salt after stirring.
    • Using a sketch pen / marker, mark the level of salt in the test tube.

    • Using a wooden skewer, stir the contents well for two minutes.

    • Observe the change in the level of salt after stirring.

  11. Let the salt settle at the bottom of the test tube. Now pour the acetone into a small container. Make sure not to transfer the salt into the container. Clean the test tube with water. Using a dropper, transfer the acetone to the test tube.
    • Let the salt settle at the bottom of the test tube. Now pour the acetone into a small container.

    • Make sure not to transfer the salt into the container.

    • Clean the test tube with water. Using a dropper, transfer the acetone to the test tube.

    • Add two units of citric acid crystals, using the measuring cup.

  12. Using a sketch pen / marker, mark the level of citric acid crystals in the test tube. Using a wooden skewer, stir the contents well for two minutes. Observe the change in the level of citric acid crystals after stirring.
    • Using a sketch pen / marker, mark the level of citric acid crystals in the test tube.

    • Using a wooden skewer, stir the contents well for two minutes.

    • Observe the change in the level of citric acid crystals after stirring.

    • Desired result is not achieved -

    • Stir well and observe closely if the salt / citric acid is getting dissolved.

    • Make a note of the number of cups of salt / citric acid crystals added each time. Making detailed and written records is an integral part of the scientific process.

    • Make sure the water is boiling when you measure the solubility of salt / citric acid crystals in boiling water.

    • Use sugar instead of salt to check the soubility of sugar.

    • Use jaggery powder instead of salt.

Finish Line

Vishal Bhatt

Member since: 04/26/2017

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