 # “Scientific Measurement”

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“Scientific Measurement”

1. What is the purpose of a measurement? 2. Why are measurements important to science?

Measurements Measurements are fundamental to science
Measurements may be: a. Qualitative b. Quantitative

Measurements Qualitative Measurement: is a non-numerical measurement
Example: The solution turned brown when ammonia was added to iron (III) chloride

Quantitative Measurements
Quantitative Measurements: consist of two parts a. A number b. A unit

Quantitative Measurements
Example: The rock has a mass of 9 kg unit Number

Practice: Classify as qualitative or quantitative
1. Water is a liquid 2. The temperature was 9°C. 3. The book is 12 cm long

Scientific Notation Occasionally some measurements are really small or exceptionally large 1, 400, 000 km, the distance to the sun , the Universal Gravitation Constant To help you use these, you may express them in scientific notation

Scientific Notation Continued
In scientific notation, a number is written as the products of two numbers: a coefficient and some power of 10

Scientific Notation Continued
The general form for scientific notation is: M x 10n where M is  1 but < 10 n is an integer and exponent {integers must be a positive or negative whole number}

Rules for Scientific Notation
1. Determine “M” by moving the decimal point in the original number to the left or to the right so that only one non-zero digit remains to the left of the decimal

Rules for Scientific Notation
2. Determine “n” by counting the number of places that the decimal point was moved. If the decimal was moved to the left, n is positive; if the decimal is moved to the right, n is negative

Guided Practice Express the following in scientific notation:
1, 400, 000 km, the distance to the sun , the Universal Gravitational Constant

Independent Practice Express the following in scientific notation:
b c d e f

Express the following scientific notations in the long form
1. 7 x 104 x 104 3. 7 x 10-5 x 1010 x 105

Express the following in scientific notation
B C. 456

SI System The SI system used prefixes “Kilo-” means 1000; symbol is k
“Centi-” means 0.01; symbol is c “Milli-” means 0.001; symbol is m “Deci-” means 0.1; symbol is d

MOST IMPORTANT CONVERSIONS
1000 grams (g) = 1 kilogram (kg) 1 mL= 1 cm3

Length Length is the distance between two points
UNIT: meter (m) or centimeter (cm) Rulers and Meter Sticks measure length

Volume Volume is the amount of space an object occupies
UNIT: L, mL, or cm3 Remember 1 cm3 = 1 mL Volume = length x width x height (solid) Graduated Cylinders measure volume (liquid)

Mass Mass is the amount of matter that an object contains
UNITS: g or Kg *Remember 1000 g = 1 kg

Mass and Weight Mass doesn’t change Weight does change
Weight is the force that the Earth exhibits on a mass. Weight is measured in Newtons (N).

Time Time is the interval between two events UNIT: second (s)

Temperature Temperature is the measure of the average kinetic energy of particles Temperature measures how hot or cold an object is UNIT: Degrees Celsius (°C)

Smart board activity

MEASUREMENT LAB

Why does ice float on water?

Density Density is a property of matter that is often used by chemists as an “identification tag” for a substance. Density = Mass / Volume (D=m/V) Units for density include g/cm3, g/mL, kg/L or kg/m3 Units : Always a mass over a volume Remember 1 mL= 1 cm3

United streaming video clip: Physical Science Series: Properties of Matter- density

You have two blocks both composed of the same type of wood
You have two blocks both composed of the same type of wood. However Block A is 1000 cm3, and Block B is 1 cm3. Which block has the greater density???

Density Continued Substances and their densities: Water 1 g/mL
Table Sugar g/mL Gold g/mL Ice g/mL Ethanol g/mL If all of these substances were poured in one container, list the order of the substances bottom to top.

Less dense objects rise.
Explain how a lava lamp works. Explain helium balloons. Explain the raisins in the carbonated beverage.

Let’s try some calculations…

1. What is the density of an object that has a mass of 5 g and a volume of 2.5 cm3?
Some liquid nitrogen has a mass of 14 grams and a volume of 36.3 mL. What is the density? A substance has a mass of kilograms and a volume of 19.8 L. What is the density?

What if you are solving for volume or mass?
Remember on the EOC you will only be given the form. D=m/v- You must know how to derive the other 2 equations Solving for volume: Solving for mass: Circle method First show students that you can solve for any one of the variables when you know the number values for two. Derive all three equations that students would possibly use for density when solving for mass or volume or density. Then stress that the only formula they will be given on the test is d=mv… but they can derive any of the other two. To help remember the other two you can do the trick with m/dv in a circle and cover up what you are solving for.

What is the mass of an object with a density of 10 g/mL and a volume of 2 mL?
How much space does 4 g of a substance occupy if it has a density of 7.6 g / mL? Talk them about how they have to recognize what they are solving for. Determine what they are solving for first, then solve the problem.

Demonstration of Density
OBJ: to see if different sodas have different densities We will use coke and diet coke to see if the two sodas have different densities Question: Based on what was observed, what can you conclude about the density of coke and diet coke? Coke is more dense b/c the corn syrup has a higher MM and b/c they have to add more to sweeten it. Aspartame, the artificial sweetner in diet coke, has a lower MM and b/c it is 200 times sweeter than corn syrup very little has to be added.

The “recycling factory”
Block lab