Creating the pH Scale (6-9)
Click the links to the right to view the online Teacher's Guide, Student Logbook, or visit WebQuest unit for this W.E.T. You can also download the Teacher's Guide and Student Logbook in either PDF or Word document format.
A water molecule is made up of ttwo hydrogen atoms and one oxygen atom. Hydrogen atoms are smaller than the oxygen and have a positive charge while the oxygen atom is bigger and has a negative charge. Because of the shape of the molecule, water has a positive end and a negative end, causing the molecule to act like a magnet. Another quality of water is called dissociation. This property of water is responsible for the formation of acids and bases. In water dissociation, a hydrogen atom breaks away from the oxygen atom. In pure water there are an equal number of H+ ions and OH- ions. The amount or number of H+ ions to OH- ions determines the pH of a substance or whether the substance is acidic, basic or neutral.
Our world would be very different if we did not have acids and bases. Most of the food we eat is acid and our stomach produces very strong acids. The acids help us digest our food. One of the few foods that we eat that is basic is beans and we all know the results of that! Our blood has a pH of about 7.3 which helps our red blood cells to carry oxygen throughout our body! If the pH of water is too high or basic, minerals can settle out of the water causing our water pipes to clog and give us low water pressure. If the pH of our water is too low, or acidic, plumbing fixtures and our hot water heaters can be damaged.
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Teacher's Guide Word (836 KB) PDF (1.8 MB) ■ Student Logbook Word (650 KB) PDF (1.5 MB) ■ WebQuest HTML template Word template |
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National Science Education Standards Content A Content B Content C Content E Content F Teaching A Teaching B Teaching D Teaching E |
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Illinois Learning Standards - Science 11.A.3.a 11.A.3.b 11.A.3.c 11.A.3.d 11.A.3.f 11.A.3.g 11.A.4.a 11.A.4.b 11.A.4.c 11.A.4.e 11.A.4.f 12.C.3.b 12.C.4.b |
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