Do Now for 2/26/13

Take out C40 write upTake out Goals Activity

Take out sheet 40.1HW: Complete analysis 5,6,7,8C40 will be checked tomorrow

C40 Parts per Million

• Today’s Target: I will be able to describe the term parts per million and observe a serial dilution.

• Check HW• Introduce activity• Gather data• Clean up• Analysis 5,6,7,8• Key Points

Parts per million

A way of expressing very dilute concentrations of substances.

Per cent means out of a hundred(100)parts per million or ppm means out of a

million(1000000) Usually describes the concentration of

something in water or soil.

Examples of ppm• Some examples of 1 millionth portion of

something

– One second in 12 days of your life– One penny out of $10,000– One inch out of a journey of 16 miles– One pinch of salt on 10 tons of potato chips

Red Food coloring solution

• Solution = Solute + Solvent

Example:(Red Food = Red Food + WaterColoring DyeSolution) (Solute) (Solvent)

C40 Parts per Million

• Lab Safety – Goggles and aprons• Follow the procedure – HOLD THE DROPPER BOTTLES

VERTICALLY!!• At the end of the activity make sure to take home a

sample of the solution on 40.1 the ‘Serial Dilution Worksheet’.

• Very Important (Begin with Cup 9 and go downwards to Cup 1)!!!

• Clean up• Answer analysis questions 5,6,7,8

C40 Parts per Million

• 5. Do you think there is any food coloring in cup 8 even though it appears colorless?– Yes. Even if we dilute something, it is still there.

We took some of the liquid from cup 7 and moved it into cup 8, and cup 7 had food coloring in it.

C40 Parts per Million

• 6. Explain how you could do an experiment to provide evidence to support your answer for question 5.– Use a microscope to look for food coloring

particles in cup 8, or let the water evaporate and see if any food coloring particles are left over.

C40 Parts per Million

• 7. Describe something a scientist might study and report using parts per million as a measurement tool.– Useful for studying and measuring small

amounts of pollutants in air or water.

C40 Parts per Million• 8. Assume someone told you that if your

water looks clear and does not smell bad, it is safe to drink. Would you follow this advice? Why or why not?– It is possible for some contaminant to be present

in clear, odorless water, even though we cannot see it or smell it, because in this investigation we know there was some of the red substance in the drop we used to make the solution that became colorless.

C40 Parts per Million – Key Points

• 1. The concentration of a solution is expressed in terms of parts of solute to parts of solvent.

• 2. The term parts per million is a way to express concentration.

• 3. Mathematical relationships (orders of magnitude and proportion) are involved in serial dilution and the expression of concentration of a solution.