Water, the Universal Solvent

Make a prediction… What will happen when you pour hot, liquid wax into room temperature water? Write and draw your prediction.

Water + Powder = What happens when you pour lemonade powder into a pitcher of water? You make lemonade, a solution. Solution – a mixture that forms when one substance dissolves another. Solvent – the substance that does the dissolving (the water)

Universal Solvent One reason that water is able to dissolve many substances is that it is polar. The charged ends of the water molecule attract the molecules of other polar substances.

Comparing Solvents With your group members, complete the Comparing Solvents activity on page 26. TIP: Keep your spoon in the correct cup. TIP: Only use toothpick to stir ONE TIME and then throw away. Dispose of liquids in cups A, B, C in the SINK. Dispose of D, E, F in the garbage. Throw the entire cup in garbage. No oil in the sink!

Conclusions 1.In which solvent did each substance dissolve better? Each of the three substances dissolves better in WATER. 2. Propose an explanation for your results. Think about the differences between polar and nonpolar molecules. The substances must have had charged particles that were attracted to water’s polar molecules, but not to the nonpolar oil molecules.

H 2 O Yeah! Water dissolves so many substances that it is often called the “universal solvent”. Other substances that dissolve in water: Solids cube of sugar in tea saltsoap Liquids bleach rubbing alcohol Gases oxygen Carbon dioxide (CO2)

Nonpolar Molecules The molecules of oil are nonpolar molecules – they have no charged regions. Some substances do not dissolve in water such as oils and wax.