Experiment 1- Is Water Hard?

by: Tonya Estep and Jessica Vaughn

Hard water is water that contains many dissolved minerals. If water is considered "hard," soap will not easily form bubbles. Distilled water is not "hard" water. We tested two types of water, distilled and tap(well), to determine if it was hard or not.

Materials: tap water, 2 screw-top jars, small open jar, distilled water, liquid soap, spoon, dropper

1. Mix liquid soap into the small jar with some distilled water.

2. Pour distilled water into one screw-top jar and the same amount of tap water into the other. Put a drop of liquid soap solution into the jar of tap water and screw on the lid.

3. Shake the jar. If it does not foam, repeat step 2 and shake it again. Count the number of drops it takes to make the foam.

4. Repeat steps 2 and 3 with the distilled water.

Did the tap water need more drops to make it foam?

Yes, the tap water took twice as many drops as the distilled water to make the same amount of foam, therefore the tap water was "hard".

So, how can you change the hardness of water? If the water is too hard, it is because of relatively high amounts of dissolved minerals like calcium and carbonates. To soften the water, use a filter that will strip the dissolved chemicals away. If the water is too soft, try adding a chemical buffer to it until it reaches the pH you want. Baking soda, or sodium bicarbonate, is a cheap chemical buffer. Limestone is another way to keep the water from becoming too soft.

Standards

GLE 0607.Inq.1 Design and conduct open-ended scientific investigations.
GLE 0607.T/E.1 Use appropriate tools to test for strength, hardness, and flexibility of materials.

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