A water particle is called a water molecule. The water molecule is a very special molecule. It has a small positive charge on one end and a small negative charge on the other end.
We can demonstrate this by using a charged balloon. View the video on the right. See how a charged object attracts the column of water.



Salt crystals are made up of small, charged particles. The water molecules are attracted to the individual salt particles forming the crystal crystal. As water molecules approach the crystal they surround each particle and separate it from the rest of the salt crystal. Individual salt particles now surrounded by water molecules float freely in the water. A salt solution is formed.

The salt is said to be soluble in water, in other words, water can move in and surround each particle thus breaking up the crystal into individual particles.

Sugar is also soluble in water and yes water also disrupts the sugar crystals by surrounding each particle of sugar and causing it to float freely in the solution. We can say that sugar particles are charged in a way as to attract water molecules to them.



Salt dissolves quicker in hot water than in cold water. The reason is that in hot water, water molecules have more energy and travel faster than in cold water. Water molecules have more energy to disrupt the salt crystal and because they move faster create more space between themselves to accommodate solute particles.

A liquid that is used to dissolve another substance is given the general term of solvent, while the substance being dissolved is known as the solute. In this case salt is the solute and water is the solvent.

Some substances are insoluble. That is, water molecules cannot dislodge the particles that make up the crystal. The particles of an insoluble substance are held too tightly to the other particles in the crystal.
Sometimes when two solutions are mixed an insoluble solid is formed. So the soluble substances in each solution combine to form a substance that water cannot pull apart and dissolve. View the video on the right to see how two clear solutions can mix to make a yellow powder.



1) Which word best describes sand in water?
2) Explain how water molecules dissolve salt?
3) What makes water molecules able to dislodge the particles of a soluble substance?
4) Water is made up of
5) In a solution of water and sugar, sugar is
Continue with separating mixtures