# Notecard Quiz Name ___________ Date _______ Period __ Activity 2, #2 Copy exactly what you have written in your notebook. Writing anything other than what.

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Notecard Quiz Name ___________ Date _______ Period __ Activity 2, #2 Copy exactly what you have written in your notebook. Writing anything other than what is already written in your notebook will result in a score of zero.

Warm up Glue study checkpoint into the warm up section of you notebook and complete it Put Unit A Major Concepts in the warm up section of your notebook after the study checkpoint After all notecards have been collected, compare your answers to the 4 square assignment

Activity 9 Sources of Error Why werent the densities you calculated for the lt. gray cylinders all 2.7 g/cm 3 and the densities for the dark gray cylinders 7.9 g/cm 3 ? Reading ruler and graduated cylinder Drops escaping from graduated cylinder Calculation errors Rounding errors Lack of precision in the instruments Balance was not accurate

Significant Figures Accuracy of Measurement What is the volume?

Significant Figures Accuracy of Measurement Would it be accurate to say that the volume is 47.85? Why or why not?

Significant Figures Accuracy of Measurement What is the volume?

Significant Figures Accuracy of Measurement Would it be accurate to say that the volume is 36.5 ml? Why or why not?

Significant Figures We want meaningful, accurate measurements… Whenever you do math with significant figures, the answer cant be more precise than the numbers it came from. http://www.mrbigler.com/Chem1-C1/topics/measurement/significant-figures.html

Example- Density Calculation If you measure the mass of an object from a very accurate digital scale, it might read: 53.235 grams If you measure the volume in a graduated cylinder, your most accurate answer might be 45.2 ml

Example – Density Calculation Density = mass / volume Density = 53.235 g / 45.2 mL You calculator will say this = 1.1777654867 But we can only use 3 significant digits because that is our least accurate measurement… Correct answer = 1.18 g/mL We will use 1.2 g/mL