# Chemistry Honors – Class 17

Dates

- Period B: Friday, September 26th
- Periods D, G: Monday, September 29th

Exam Recap

- General trends / observations about the exam
- reminder about “bucket of points”
- individual questions? see me during OH or other time

Lab Activity – Counting by Mass

Data

- Count out 25 pieces of an item and determine the mass
- Grab a handful of the same item (without counting) and find its mass
- Then count number of items in unknown sample
- record important observations of each item
- Repeat for as many materials as possible

Calculations (for each item)

- Calculate the number of unknown items
- Compare calculated number to the known, counted, number (percent error)
- Calculate the mass of one dozen of each item.
- Calculate the mass of one million of each item.
- Determine how many of each would be needed to make 1.00 kg
- Calculate the mass of 1 mole of each item (1 mole = 6.02 x 10
^{23})
- Determine the moles of each item that are equivalent to 543 pieces
- Define mass. Discuss the difference between mass and weight.
- Discuss the advantages of counting by mass as compared to counting manually

Coaching

- NO CROSS MULTIPLY – how do I show this? Units?
- How do I show calculations in my LNB?
- How many examples do I need to show?
- What is a data table?
- What is a calculation table?

Support Material

- I have created a sample of what this lab could look like
- Posted in the “Lab Work” section of the “Materials” part of the course Schoology site.
- Please try and model your work after the posted document.

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