Unit 2 – Day 8 Wednesday October 9 th

Candle Lab Drill Answer in complete sentences or copy questions: 1. As a candle melts all the way down, how does the amount of wax change? 2. What colors did you see in the flame? 3. Did the flame touch the wax? 4. Could the flame burn the wire mesh? 5. What did you see on the bottom of the beakers that you held above your flames? 6. How many significant digits: A.1,000.0 m B. 4 mLC. 3 x 10 3 L

CANDLE LAB PART TWO Answer these questions in complete sentences in your lab notebook. 20 points + the 10 points for your observations = total lab grade for candle lab.

CANDLE LAB QUESTIONS # What states or phases of matter were present inside the candle flame? 1 – 2. What observations prove that each state of matter you listed in question 1 – 1 was present in the flame ?

CANDLE LAB Questions # 2 States of matter: 2 – 1. Was your flame just gas or was it a mixture of gas and solid? Give two reasons supporting your choice.

CANDLE LAB Questions # 3 Freezing, Melting & Boiling Points 3 – 1. The metal heated so that it glowed orange, but did not burn or melt. Why? 3 – 2. What were the two possible fates of the liquid wax that melted near the candle? 3 – 3. Is the freezing point of liquid wax higher or lower than room temperature?

Candle lab question # 4 4 – 1. Why did the flame go out after you covered your candle with an Erlenmeyer beaker? 4 – 2. What are the three ingredients necessary for combustion to happen?

Matter changes states in candle lab: Before flame is lit: –Candle is a solid When candle is burning: –Wax is still solid in most of the candle –Wax is liquid near flame –Wax is changed into a mix of gases and tiny new solids inside the flame

Gases Indefinite Shape & Volume A gas with a lot of energy will give off light (This is why fire is visible) Types of gas mixtures: –Different gases –Gas with liquid (aerosol cans) –Gas with small solids (pollution, smoke)

Gas Colors In the candle lab – the flame is a gas that has so much energy that it gives off light. The flame is orange when there is still some solid fuel (wax) mixed in with the gas The flame is blue when it is pure gas.

Solids – p 34 & 340 Atoms or molecules do not move around, just vibrate in place Add heat (i.e. fire from a match) and movement gets faster Once movement is fast enough, solid becomes a liquid or even a gas

Solids – p 34 & 340 Temperature at which solid changes to a liquid = melting point Temperature at which liquid changes to a solid = freezing point Melting point = Freezing point –SAME TEMPERATURES!

COMBUSTION = fire In candle lab Wax = fuel Oxygen  reacts with the fuel Match = energy Combustion in general: Self-sustaining Releases heat

Density & Phases (or states) of Matter Density is intensive  It does not change based on how much volume of matter you are looking at  D 10mL = D 20mL = D 30mL = D 40mL = 1g/mL  The scientifically accepted value for water density at room temperature (22 degrees C) is 1.00 g/mL When does the density of water change?  When matter changes phases, solid H 2 O (ice) has a lower density than liquid H 2 O

Why? When water becomes a solid, the water molecules stop sliding past each other. No two snowflakes ever the same Solid ice has a predictable pattern that is the result of the way the water molecules “hold each other” in place.

You have this in your notes Physical state (solid, liquid, aqueous & gas)  A measure of how much energy matter has. Solid = less energy  Liquid = more energy  Gas = most energy

Remember this slide? Matter at the Chemistry Scale Mixtures - homogenous - heterogeneous Pure Substances - Compounds  molecule is smallest or - Elements  atom is smallest

Phases/States of Matter SOLIDS Molecules or atoms are all fixed in place When enough energy is added, molecules/atoms start moving  solid becomes a liquid The temperature at which that happens is the melting point

Phases/States of Matter LIQUIDS Molecules/atoms have enough energy that they move around, bumping into each other all the time Add enough energy and molecules/atoms move so fast that they escape as gases. The temperature at which this happens is the boiling point

States/Phases of Matter GASES Molecules/atoms are so far apart as to never bump into each other