4.2 Physical and Chemical Properties and Changes pgs p1eG2y2mn54

(Do Not Copy)  Question: How would you describe your lost piece of luggage at the airport?  Answer: You would report its colour, shape, size, etc…You are describing the physical properties of your lost item.

Physical Properties  Determining physical properties does not change the composition of the substance  Physical properties are determined by observing a substance using the 5 senses

Qualitative Physical Property  A property of a substance that is not measured and does not have a numerical value, ex: colour, odour, texture Quantitative Physical Property  A property of a substance that is measured and has a numerical value, ex: temperature, height, and mass.

 “Physical Properties of Matter”table p. 151 use table to supplement your notes/study (7 total in course) PHYSICAL PROPERTY DESCRIPTIONExamples Colour and Lustre (Lustre – shininess or dullness) The light a substance reflects gives it colour and lustre (shine) Gold – is the name of substance but also the colour, shiny so has high lustre ConductivityThe ability of a substance to allow an electric current to pass through it or conduct heat Most metals are good conductors Most non-metals are insulators (do not conduct heat/electricity)

PHYSICAL PROPERTY DESCRIPTIONExamples DensityThe amount of mass in a given volume of a substance D=m/V Pure water has a density of 1g/mL and pure gold is 19g/mL (sink or float)

PHYSICAL PROPERTY DESCRIPTIONExamples Ductilitythe ability of a substance to be pulled into a finer strand/wire Copper is a common material (copper wire) Hardnessthe relative ability to scratch of be scratched by another substance -scale used from 1 to 10 Chalk 1 versus diamond 10 – which one would scratch the other? (diamond harder than chalk)

PHYSICAL PROPERTY DESCRIPTIONExamples Malleability the ability of a substance to be hammered into thin sheets Aluminum metal can be made into aluminum foil (also tin into tin foil) Viscosity The resistance of a fluid flow (slow to pour has HIGH viscosity) Molasses, real maple syrup HIGH viscosity Water, vinegar LOW viscosity (fast pouring)

Physical properties of water  Water “sticks” to itself called COHESION Ex. Water forms beads on non absorbent surfaces such as glass  Water also “sticks” to other substances called ADHESION Ex. You can mop up water using a towel  Water expands when it freezes and becomes less dense Ex. Ice floats on liquid water – most materials shrink when they freeze

Water Less Dense When Frozen  Imagine pond water freezing at the bottom! What would happen to our fish?

Negative Consequences of Water Expanding...  Water freezing causes serious problems such as expansion of glass bottles in a freezer and pipes bursting in the winter  TIP: Always empty water pipes in the winter!

Physical Changes  A change in which the composition of the substance remains unaltered and no new substances are made

Clues that a PHYSICAL change has happened… 1. Change in shape or form but NO new substance is produced 2. Change of state 3. Solubility (Dissolving) 4. MOST but not all PHYSICAL CHANGES ARE EASY TO REVERSE

 Example: Change in STATE  Add heat to an ice cube until it melts. The ice cube was a solid now it’s a liquid. Both the ice and liquid are made from water   Wax melting (solid  liquid) Physical Change

 Example: Sugar/salt dissolves in water, the sugar/salt is still present as sugar/salt  SOLUBILITY is PHYSICAL!!!!  Process can be reversed by evaporating the water  sugar will remain

Corn and Plastic  tuffworks.com/ corn-corn- plastic-video.htm tuffworks.com/ corn-corn- plastic-video.htm

Homework for physical only  Read 4.2  P. 153 # 1, 2  Complete p. 161 #1, 5, 6, 10