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# lecture2sf - Temperature Scale Celsius Scale Fahrenheit...

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Temperature Scale Celsius Scale Fahrenheit Scale A change of 100 degrees Celsius is equivalent to a change of 180 (212-32) degrees Fahrenheit. The ratio is = 1.8. Also, when Celsius starts at 0, Fahrenheit starts at 32 (both equivalent to the freezing point of water). This gives rise to the formula: T F = 32 + 1.8 T C The Kelvin scale (K) has a different zero point than Celsius but each degree change is the same: Kelvin Temp. = Celsius Temp + 273.15 K = o C + 273.15 A lead brick has dimensions of 10.22 cm x 10.18 cm x 4.98cm and weighs 13.0 lb.

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What is the density of the brick in 3 cm g Given: 454 g = 1 lb 3 cm ) 98 . 4 )( 18 . 10 )( 22 . 10 ( lb 0 . 13 x 454 lb g = 11.4 3 cm g A thin piece of lead foil has a mass of 1.50 g. What is its density? Density is a intensive property . It does not depend on the amount of matter. If the foil is pure lead, the density is 11.4 3 cm g , regardless of the size of the sample. Intensive properties are useful in describing and identifying a substance. Besides density, other intensive properties are melting point and boiling point. Mass and volume are extensive properties , which are different for each size of sample. A bar of “gold” measures 2.00 cm x 15.0 cm x 6.00 cm and has a mass of 3290 grams. Is it gold? Density = 3 cm ) 00 . 6 )( 0 . 15 )( 00 . 2 ( g 3290 = 18.3 3 cm g Pure gold has a density of 19.3 3 cm g The bar is not pure gold.
Density is a property commonly used to describe and distinguish substances. Different substances vary widely in their densities. Substance Density ( 3 cm g ) at 20 o C Water 1.00 Ethanol 0.789 Lead 11.3 Mercury 13.6 Gold 19.3 Aluminum 2.70 Magnesium 1.74 Sodium chloride 2.16 Oxygen 0.00133 Hydrogen 0.000084 Classification of Matter

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| | ____________|__________________ | | | | | | | | | | _____ |________ _____|__________ | | | | | | | | | | | | | | | | (solutions) What are the differences between compounds and mixtures? Compound Mixture Definite Composition No definite composition
Have different properties Has average properties than elements making of substances in the up the compound mixture Can be separated into Can be separated into its elements only by its components by physical chemical reactions means (filtration, distillation, chromatagraphy). Examples Is water a compound or a mixture? Water has the formula H 2 O, always 2 atoms of hydrogen for one atom of oxygen. It has a definite composition by mass, always 88.9% oxygen, and 11.1% hydrogen. Water is a liquid essential for life. Hydrogen is a light combustible gas; oxygen is a gas which supports combustion. Water can be broken down into hydrogen and oxygen by very high temperatures or electrolysis. These are chemical reactions. By all the above criteria, water is a compound. Is common table salt, sodium chloride, a compound or mixture?

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lecture2sf - Temperature Scale Celsius Scale Fahrenheit...

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