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Scientific Notation
Scientific Notation
Scientific notation is a scientific method to write a very large or very small number, so that people can perform further calculations more easily.
How to write a number in scientific notation:
- Make significant figures between 1 to 9.99…
- Assign the power of 10 accordingly after the significant figures.
Using 538000000 as an example,
- Make significant figures between 1 to 9.99… (5.38)
- Assign the power of 10 accordingly after the significant figures. (5.38 x 108)
More examples:
- 47390 = 4.739 x 104
- 300000000 = 3 x 108
- 0.00038472 = 3.8472 x 10-4
- 0.002 = 2 x 10-3
Most common SI prefixes and symbols
Most common SI prefixes and symbols
Microscopic view of atom
Microscopic view of atom
(Structure of an atom, CNX OpenStax / Wikimedia Commons / CC-BY-SA-4.0)
What is isotope? If you don’t want to know, just take the larger number as relative atomic mass in the element symbol when calculating.
Molar mass = addition of relative atomic mass of a molecule (e.g. molar mass of NaCl = (23.0+35.5)g = 58.5g)
Mole and Avogadro constant
Mole and Avogadro constant
Mole (symbol: mol) is a special unit used to describe the quantity of particles in a substance. Avogadro constant (6.02 x 1023) is the number of atoms in exactly 12.0g of carbon-12. (if you don’t understand this, just read on.) 1 mole of particle = 6.02 x 1023 particles. Just as 1 dozen of eggs = 12 eggs; 1 ream of paper = 500 sheets of paper. 1 mole of any substance contains 6.02 x 1023 formula units. For example, 1 mole of water contains 6.02 x 1023 H2O molecules ; 2 moles of copper contains 1.204 x 1024 copper molecules.
Concentration and molarity
Concentration and molarity
1 dm3 = 1000 cm3
Serial dilution
Serial dilution
Purpose
Purpose
To dilute a solution stepwise in logarithmic sequence
Procedure
Procedure
- Fill all tubes with same volume (e.g. 900 μL) of distilled water
- Add a volume (e.g. 100 μL) of stock in to the first tube
- Mix solution by pipetting up and down
- Transfer the same volume (e.g. 100 μL) of stock to the subsequent tube
- Repeat steps 3 and 4 until the last tube
In this example, the dilution factor is 10X. i.e. for, the concentration of the subsequent tube is 10 times less concentrated than that of the previous tube.
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