1. If you have two identical size containers, but one is filled with zinc that has a density of 7.14 g/cm3 and one is filled with copper that is 8.96 g/cm3, which one would feel heavier?
A) ZINC B) COPPER
1. If you have two identical size containers, but one is filled with zinc that has a density of 7.14 g/cm3 and one is filled with copper that is 8.96 g/cm3, which one would feel heavier?
B) COPPER
2. Why did the pre 1982 pennies have a higher density than the post 1982 pennies? A. There were more pennies in one sample than the other B. The pre 1982 pennies were made with copper, while the 1982 pennies must be made with something else
2. Why did the pre 1982 pennies have a higher density than the post 1982 pennies? B. The pre 1982 pennies were made with copper, while the 1982 pennies must be made with something else
3. What do you think would float in oil that has a density of 0.91 g/mL? A. Plastic bead with a density of .67 g/mL B. Copper penny 7.25 g/mL
3. What do you think would float in oil that has a density of 0.91 g/mL? A.Plastic bead with a density of .67 g/mL
Cerium Ce 6.77 Cesium Cs 1.93 Chromium Cr 7.15 Cobalt Co 8.86 Copper Cu 8.96 Dysprosium Dy 8.55 UraniumErbium UEr 19.19.07 Vanadium V 6.0 Ytterbium Yb 6.90 Yttrium Y 4.47 Zinc Zn 7.14 Zirconium Zr 6.52 DENSITY Things that are more dense than their surroundings will sink.
What is more dense? It has mass and takes up space Everything around us is matter We have learned that we can classify matter based on it’s composition
How does it look? Color, sheen, texture What does it weigh? How does it react? Can it poison us?
Physical Properties Chemical Properties Definition: can be observed without altering the chemical composition of a substance Examples: color, texture, malleability, solubility, mass, volume, density, melting and boiling points Maleability- Able to be pounded out and shaped Solubility - The ability of something to dissolve Density- How much mass per unit (volume) of matter
D=m/v Color? Texture? Malleability? Mass? Solubility?
Physical properties can be described as being intensive or extensive.
• Dependent on size • volume, mass, and length – this property changes when you change the sample size
• do not change with the sample size • can be useful in identifying a substance color, density, viscosity (how thick/thin or slippery), temperature, solubility, and states of matter. • EXAMPLE: DENSITY • What if you had a 1 kg Chocolate Bar (BIG) with a density of 5g/ml • Mass- 1000g • Volume- 200mL • D=m/v • D= 1000/200 • D=5g/mL
• EXAMPLE: DENSITY • If I cut it in 2, each half would now be 100mL in size (volume) and 500g in mass • D=m/v • D=500/100 • D=5g/mL • same density!!
Definition: the characteristics (ability) of a substance to combine with or change into other Toxicity, reactivity, flammability, radioactivity Toxicity? Non- toxic Reactivity Very low Flammability? Non-flammable Radioactivity? I sure hope not!! Kids play with this stuff!
The boiling point of a certain alcohol is 75 degrees Celsius
Physical Copper forms green copper carbonate when in contact with moist air Chemical Table salt dissolves in water Physical Copper is a good conductor of heat and electricity
Physical Magnesium burns brightly when ignited Chemical Iron is more dense than aluminum
Physical Want to see something on our period table that is pretty dense? And pretty toxic? Solubility
Solubility - The ability of something to dissolve
In a solution, the solute is dissolved in the solvent. What affects solubility?
Temperature of the solvent
Size of solute (surface area)
Agitation of solution (stirring/shaking) Solubility – 3 Levels 1. Saturated The maximum amount of solute that can be dissolved at a particular temperature is dissolved.
We also call this the saturation point. SATURATED SOLUTION What would happen if you reached the saturation point of sugar in your iced tea that had a temperature of 25 degrees C, but you kept adding more sugar? 1. What would happen to the sugar when you added more? 2. What could you do to get it to dissolve? Solubility 2. Unsaturated More solute can be dissolved. It has not reached the saturation UUUGGGHHHH!! point Jake, you made this Kool-Aid SO WEAK it sucks! Add more solute!! Solubility 3. Supersaturated More solute -than should be dissolved at that temperature -is dissolved. Precipitate – stuff that “falls out” and can„t dissolve Usually achieved when we cool something down after making it saturated at a higher temp…like rock candy..
MMMNNN…. Sweet luscious rock candy!! This shows the solubility curves for different substances
The NaNO3 is more soluble in 400 water than KNO3 These are LINES OF SATURATION for different substances
How much
NaNO3 can be dissolved in water that is 30oC?
What temperature must water be warmed to in order to dissolve 80g of
KNO3?
30g of KCl is dissolved in water warmed to 80oC. Is the solution saturated, unsaturated, or supersaturated ?
100g of NH4Cl is dissolved in water warmed to 50oC. Is the solution saturated, unsaturated, or supersaturated?
FOLD A PIECE OF NOTEBOOK PAPER INTO 2 COLUMNS AND WRITE THESE TITLES
Physical Changes Chemical Changes Matter can change Examples: Freeze, cut, burn, etc. 2 types of changes 1. Physical changes 2. Chemical changes
PHYSICAL CHANGES vs. CHEMICAL CHANGES What’s the Difference?...... Physical Changes Definition: when the state or form of matter is changed physically or mechanically (but it is still the same stuff) –no new substances Examples: breaking, cutting, freezing, melting, etc.
CLUE OF A PHYSICAL CHANGE…”Can it be turned back into how it started?” Yes Physical Changes Examples: breaking, cutting, freezing, melting, etc. Physical Changes Examples: breaking, cutting, freezing, melting, etc. Chemical Change Definition: a change on the molecular level (reaction) and produces a new substance. A chemical change always involves a chemical reaction
Where is the Evidence??? Evidence of chemical change: color change, gas production, and release of heat, light, new smell, or sound. Examples: Burning (combustion), rusting, tarnishing and fermenting
Where is the Evidence???
Examples: Burning (combustion), rusting, tarnishing and fermenting
Let’s Practice Hold up your card and show P for a Physical Change or C for a Chemical Change A chemical change always involves a chemical reaction
ice melting burning a chemistry book melting iron frying an egg fireworks exploding in the sky turning wood into a baseball bat baking a cake sharpening a pencil sulfuric acid added to sugar
http://www.youtube.com/watch?v=nqDHwd9r G0s carving a watermelon into a creepy looking face pouring liquid nitrogen into a bowl and watching it vaporize Ticket out the Door 1. A lot of medicines are kept in dark brown bottles (not clear) to protect them. What kind of change (do you think) is being prevented by keeping the sunlight out? Physical or Chemical
2. If you let saltwater evaporate, the salt is left behind. This is a method of making drinking water from sea-water called desalination. Is this a physical or chemical change?