Unit 2 MATH OF CHEMISTRY 2.6 Are scientists always 100% correct? AIM: How do we calculate percent error ? DO NOW: Please answer the following question.

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Presentation transcript:

Unit 2 MATH OF CHEMISTRY 2.6 Are scientists always 100% correct? AIM: How do we calculate percent error ? DO NOW: Please answer the following question Find the volume that 35.2g of carbon Tetrachloride (CCl 4) will occupy if it Has a density of 1.60 g/mL. Density = mass volume 1.60g/mL = 35.2g ? V= 22mL

WHAT IS PERCENT ERROR? Allows us to measure how far off we are from the theoretical (accepted) value Formula %Error = Theoretical – Experimental x 100 Theoretical Theoretical  accepted, actual, known

Another way you may see the formula….. Formula %Error = Actual– Measured x 100 Actual

ACTIVITY Directions: Use the M&M Activity worksheet to complete this part of the lesson. 1.Record your MEASURED VALUE (experimental) 2.Record the ACTUAL VALUE (theoretical) 3.Calculate the percent error.

LET’S TRY SOME Working in the laboratory, a student finds the density of a piece of pure aluminum to be 2.85g/mL. The accepted value for the density of aluminum is 2.699g/mL. What is the student’s percent error? Step 1. Locate theoretical and experimental values Theoretical = 2.699g/mL Experimetal = 2.85g/mL Step 2. Plug into the formula and solve %Error = 2.699g/mL- 2.85g/mL 2.699g/mL X 100

NEXT Complete the Percent Error Worksheet When you are done, you may work on the following: CHEMISTRY VOCABULARY JOURNAL - you will be allowed to use this on your quizzes and (some of) your exams