# Part 1 SI unit

#### What is SI unit?

The international System(SI) of metric units is a comprehensive set of units of measurement.
base units and additional units that are used in chemistry11
This table contains the base units in the international system (the forth 4 rows, from meter to mole) and some additional units that used in Chemitry11. The full base units are not show in this t able because we won't use it this year.

 Name Quantity Symbol meter length m gram* mass g* second time s mole Amount of substance mol litre volume L tonne mass t
*In the SI system the base unit of mass should be kilogram but gram is considered to be the base unit in Chemistry11.

#### SI prefix

These prefix are prefix used most frequently in Chemistry 11.

 Written Prefix Prefix symbol Equivalent exponential mega M 106 kilo k 103 deci d 10-1 centi c 10-2 milli m 10-3 micro μ 10-6

#### For Pracise

1. Re-write the following using PREFIX and UNIT SYMBOLS and the FACTOR it represents:

a) 2.5 centimetres c) 25.2 millimoles e) 0.25 megalitres
b) 1.3 kilograms d) 5.1 decigrams f) 6.38 micrograms

2. Re-write the following using PREFIX SYMBOLS, and WRITTEN PREFIXES and UNITS

a) 4.5 x 10-3 mol c) 0.50 x 10-6 L e) 8.85 x 106 s
b) 1.6 x 103 m d) 2.68 x 10-1 g f) 7.25 x 10-2 m

# what is metric conversions?

The metric conversions is an international decimalised(means transform) system of measurement.
here are some prefixs that you can use

#### Example : Express 3s into milliseconds

unkown amount=# of ms
Initial amount= 3s
1 ms =103 milliseconds
#of millisecongds=3s x 1 ms/10-3 =3 x 103 ms

Exercise:
1. Express 3.5 mL/min in microlitres/second
2. Express 80.0 Mg in micrograms.

Read text book page19-23 for the same stuff.