MEASUREMENT and Conversions!!

A measurement describes a QUANTITY, that is, a NUMBER, and a UNIT that names the standard used. Eg.: 50 cm, 20 kg The units used in Chemistry are obtained from the METRIC or Le SYSTEME INTERNATIONAL (SI) systems.  

The base units are listed on pg. 16(m, kg, s, K, mol, A, cd…) The metric system was developed in the early 1800's and has now become the universally accepted standard of measurement. It is based on units or powers of TEN (10). The base units are listed on pg. 16(m, kg, s, K, mol, A, cd…)   gram g

Giga (G)– 1 billion Deci (d) = 1 Tenth Mega (M) – 1 million Centi (c) = 1 hundredth Kilo (k) – 1 thousand Milli (m) = 1 thousandth Hecta (h) – 1 hundered Micro (u)= 1 millionth Deca (da) – Ten Nano (n) = 1 billionth

To make the unit larger or smaller in accordance to what you want to measure, use PREFIXES (name in front of the #) . Eg. To measure the distance to Vancouver… use km but to measure the size of a cell use µm. ** Converting from one UNIT to another is done by eliminating units systematically. HINT: Always put what you want to get out of on the bottom, and what you want to get into, on the top of the equation! VS

Try some conversions… Answer: 0.8 L 𝟓𝒖𝒔 × 𝟏 𝒔 𝟏𝟎𝟎𝟎𝟎𝟎𝟎𝒖𝒔 = ? Express a time interval of 5 microseconds (5 µs) in seconds. 𝟓𝒖𝒔 × 𝟏 𝒔 𝟏𝟎𝟎𝟎𝟎𝟎𝟎𝒖𝒔 = ? Answer: 0.000005 s 2) Convert 8 deciliters into Liters. 𝟖 𝒅𝑳× 𝟏𝑳 𝟏𝟎𝒅𝑳 = ? Answer: 0.8 L Just getting to the base unit of seconds/Litres…

How about another… or… 2.4 x 109 um 3) How many micrometers in 2.4 Kilometers? *start with what you are given… get to base…go on 2.4𝒌𝒎 × 𝟏𝟎𝟎𝟎𝒎 𝟏𝒌𝒎 × 𝟏𝟎𝟎𝟎𝟎𝟎𝟎𝒖𝒎 𝟏𝒎 = ? Answer: 2400000000 um or… 2.4 x 109 um

DERIVED UNITS are made(derived) by using combinations of other UNITS. Eg.: m/s N/m2 kg·m/s2 They were developed in order to allow scientists to gather more meaningful QUANTITATIVE observations about their surroundings. ( See pg. 23 for more common derived units.)  (m2, m3, N, Pa, J, W, V, Hz, C)

Converting areas and volumes to different units can also be done if you remember that: AREA= L x W (units 2) VOLUME= L x W x H (units 3) Note: Make sure the values are in the same units!!  

Try One more! Answer = 2.78m2 30 𝑓𝑡 2 × 1 𝑚 2 10.759 𝑓𝑡 2 = ? You are making a chicken coop. You want to make it 30 square feet, but the material only comes in square meter lengths. What do you need to know in order to calculate how many square meters of material you need? 3.28 feet = 1 m 10.759 ft2 = 1 m2 30 𝑓𝑡 2 × 1 𝑚 2 10.759 𝑓𝑡 2 = ? Biker chicks Answer = 2.78m2

Note: When you are going from a smaller unit to a bigger unit (ie Note: When you are going from a smaller unit to a bigger unit (ie. Microns to kilos) the answer is smaller. And when you go from a bigger unit to a smaller unit – the answer is bigger! 5,000,000 um to m… is 5 m.

Don’t get confused with your numbers and units!! Do “Metric Conversion (SI)” Worksheet Show your work on a separate piece of paper!!! Don’t get confused with your numbers and units!!