Avogadro’s number. Source unknown, but if it’s yours, please contact me and I will offer proper credit.
For the past week, I’ve been teaching the mole concept and conversions between moles, mass, and particles, and even though I remember being somewhat confused by the concept when I was a student, I can’t figure out why this topic is so difficult year in and year out.
Part of me thinks it’s simply the magnitude of the number: 6.02e23, or 602sextillion, is just too big for humans to actually comprehend. But a mole is really just a name for a number, like a dozen (12) or a gross (144). So why is it that Avogadro causes so much grief? Here’s TED-Ed’s take on the mole.
Maybe it’s the dimensional analysis (ladder method) used to convert between moles, molecules, and mass? So many students tell me that they can’t remember when to multiply and when to divide, but that’s exactly what the ladder method does: it’s just an organizational tool! I’ll let Mr Andersen from Bozeman Science explain the conversions.
Sorry I can’t be in class today, kids – I know you’re disappointed to have a cover teacher – so here’s the low-down on what you need to do while I’m out:
- Review the homework problems to make sure you have the correct answers and understand the process. The process is more important than the answers.
- Watch the dimensional analysis video linked here, then complete the quiz on that website to verify you understand how to do dimensional analysis.
- Go through my zombie presentation – yes, zombies do in fact know how to do dimensional analysis – and work all the practice problems in the presentation. You may do this with a partner if you want, and I’ll go over the answers with you next lesson.
- Review the document titled, “How to create graphs for science” and create a bullet-point list of all the required parts of a scientific graph. I’ll check this list as another homework check next lesson.
Here’s the zombie presentation:
Here’s the “How to create graphs for science” document in a viewing window:
Here are some tools to help you through the Measurements in Science homework assignment.
The video linked here methodically takes you through the dimensional analysis process, and it includes a quiz so that you can check your understanding.
This page has a lot of practice problems worked out for you, and it explains the process in easy-to-understand language.
Here’s the presentation we’ll use in class. Watch it. Study it. Master it.
Oh, and here’s another link that may be helpful. From Texas A+M University.
Your first unit test is rapidly approaching! It will be a 5-part test on Friday 6 September (9A and 9C) and Monday 9 September (9B). Here are the 5 sections of the test:
- Common equipment – identify by name and use
- Lab safety rules – explain them
- Unit conversion and dimensional analysis – like the HW assignment
- Demonstrate use of graduated cylinder, electronic balance, and Bunsen burner
- Create a data table and a graph from given raw data
Please note that part 4 is a demonstration stage. Each student will be called to the central demo table, where I will observe your skills using a graduated cylinder, electronic balance, and Bunsen burner. You will have exactly 2 minutes to accomplish 3 tasks with these tools, so please make sure you are comfortable using them!
The test will be scored under Criterion C (Scientific Knowledge) and Criterion F (Attitudes in Science).