__Unit 1__

Measurement

__Unit 1__

BJU: Ch. 3

Apologia: Ch. 1

Class preparation: Skim the assigned reading ahead of time, and come to class ready to participate in discussion!

__Reading__BJU: Ch. 3

Apologia: Ch. 1

Class preparation: Skim the assigned reading ahead of time, and come to class ready to participate in discussion!

In this first Unit of Chemistry, we begin by covering the metric system and related concepts that have to do with "measuring things". We will also discuss lab safety, and do a glassware lab which you will enjoy.

Below: The famous "Elephant Toothpaste" lab. We will do this one when we get to 'catalysts'. It uses hydrogen peroxide (H2O2), liquid soap, and a catalyst such as manganese dioxide (MnO2) or potassium iodide (KI). The catalyst causes the H2O2 to rapidly break down, producing copious amounts of foaming oxygen gas.

__Lecture outline__

Metric system

- In chemistry we use the metric system
- We use 'conversion factors' to convert between units
- Your textbook has some common Conversion Factors. We will discuss in class.

Unit prefixes

- The metric system uses prefixes, like "milli" or "kilo", to indicate how large the unit is.
- A kilogram is 1,000 grams. A millimeter is 1/1000th of a meter. And so forth.
- Your textbook has a table with the SI Unit Prefixes. We will discuss...

Accuracy vs. Precision

Significant Digits

Scientific Notation

Steps in problem solving

- Accuracy is how close you are to the "true" value. Shooting an arrow directly in the bullseye is being 'accurate'.
- Precision has to do with 'repeatability', or how tightly grouped your measurements are. Shooting 10 arrows near the bullseye is 'precision'.
- Precision is also an indication of how small the scale 'gradations' are on your measuring instrument. A measurement like 5.125 L is "more precise" than 5.1 L, for example (even though neither one is perhaps very "accurate").

Significant Digits

- When we measure things in chemistry, we have to be careful how many digits we show in our answer.
- Your book give some rules on how to determine how many significant figures to keep.
- For addition & subtraction, you can keep as many place values in your answer as the least precise measurement contains
- For multiplication & division, you can keep as many significant figures in your answer as the measurement with the least significant figures has

Scientific Notation

- Chemistry uses very small - and also very large - numbers. We use scientific notation to write these numbers.
- For example, 6 x 10^3 means a 6 with 3 zeroes, or 6,000.... 6 x 10^23 means a 6 with 23 zeroes!... which is a really huge number.

Steps in problem solving

- Read the problem statement. What exactly are they asking for?
- Determine the method of solution. What formula can you use?
- Plug values into the formula
- Solve, using a calculator
- Check your answer for reasonableness!

__Lab__

Glassware fabrication & safety lab

Objectives: Go over the basic safety rules pertaining to chemicals, glassware, and heat sources. Learn how to safely cut, bend, and draw glass. Make a functioning laboratory wash bottle.

__Homework__

Your class emails will give the due dates and instructions for homework. Don't work ahead, and don't do homework problems which haven't been assigned! As a general rule, you will have one homework assignment due each week.

1._conversions_homework__problems.docx |

measurement_homework_problems.docx |

1._safety_and_glassware_lab_writeup.docx |