Physical versus Chemical Properties The study of matter Adapted by NCDPI – Unit 2 Matter All...
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Transcript of Physical versus Chemical Properties The study of matter Adapted by NCDPI – Unit 2 Matter All...
Physical versus Chemical Properties
The study of matter
Adapted by NCDPI – Unit 2 Matter All Around us
• Matter: anything that has mass and takes up space– Mass – the amount of matter in something– Volume – the amount of space something
occupies
• Which of the following is matter?– A car?– A box?– You?
Reviewing MATTER
What is a property?
• Property: a characteristic of a substance that can be observed
Physical Property
Physical property: a property that can be observed without changing the identity of the substance.
Examples:
• luster
• malleability: the ability to be hammered into a thin sheet
• ductility: the ability to be stretched into a wire
• melting point
• boiling point
• density
• solubility
• specific heat
Special Physical Properties
• Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure
water = 0oC or 32ºF
https://www.google.com/imgres?imgurl=https%3A%2F%2Fc1.staticflickr.com%2F3%2F2553%2F3762687310_9a98912066_z.jpg%3Fzz%3D1&imgrefurl=https%3A%2F%2Fwww.flickr.com%2Fphotos%2Fstevendepolo%2F3762687310%2F&docid=zWwuOvFsLfk-wM&tbnid=MCq9jvJrpgPYzM%3A&w=640&h=427&ei=dRY7VOfbJ_O88QGa9YHIAQ&ved=0CAIQxiAwAA&iact=c
Special Physical Properties
• Boiling point: the temperature at which a substance changes from a liquid to a gas at a given pressure
water = 100oC or 212ºF
Chemical Properties• Chemical property: a property that
can only be observed by changing the identity of the substance
Examples:
Flammability
ability to rust
reactivity with vinegar
Density• Density is the amount of mass per
unit of volume. (how much matter is packed together)
• Density can be used to identify a substance.
• The density of water is 1.0g/mL
Density• Examples
• Helium filled balloons are less dense than density of air
• Hydrometer is used to test
• the density of Antifreeze.
Density – more examples• How can you float 7 different liquids in layers?
Density Calculations
• Calculations:D = m/V = g/mL = g/cm3
• Ex: A cube has a mass of 2.8 g and occupies a volume of 3.67 ml. Would this object float or sink in water?
Mass = 2.8 g Volume = 3.67 mLD = 2.8g/3.67 mL= 0.76 g/mL
– This object would float in water because its density is less than water (1.0 g/mL).
More Density Calculations
• Ex: A liquid has a mass of 25.6 g and a volume of 31.6 mL. Use the table below to identify the substance.
Substance Density (g/ mL)
Mercury 13.6
Water 1.00
Ethanol 0.81
M=25.6 g V=31.6 mL
D = 25.6 g/31.6 mL
D= 0.81 g/mL
The substance is ethanol.
Specific Heat• Specific Heat is the amount of energy
needed to raise one gram of a substance by one degree Celsius
http://arenahanna.wordpress.com/specific-heat-energy/
Solubility• Solubility is the ability of a substance to
dissolve (become trapped in) another substance. Solubility is based on polarity (the distribution of charge in a compound).
• https://www.google.com/imgres?imgurl
Solubility
• A solution is formed when one substance dissolves in another substance.
• The substance that “dissolved” is called the solute.
• The substance that is “doing the dissolving” is called the solvent.
• Water is the universal solvent.
Polarity• Polarity is an uneven distribution of charges in
a molecule. Ex. Water molecule
• Polar compounds will dissolve other polar compounds as well as ionic compounds. Non-polar compounds will dissolve other nonpolar compounds.
• Water is polar and
• Oil is nonpolar.
• Their molecules do
• not attract each other.