Chapter 1+ Objectives

Chapter 1+ Objectives - Chapter 1 Objectives Significant...

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Chapter 1 – Objectives Significant Figures: - All nonzero nu m b ers are significant ( 234 = 3 sig fig) - Zero’s b etwe en nonzero nu m b ers are significant ( 1006 = 4 sig fig) - Zero’s in front are NOT significant (0.00 5 = 1 sig fig) - Zero’s at th e e nd are significant (0.00 500 = 5 sig fig) - Ambiguous Sig Fig ie. 200, 50 = uncertain; zero could be intended as a significant figure, or it might just be there as a placeholder * To correct, write as scientific notation: 200 = 2 x 10^2 Multiplying/Dividing Sig Figs : look for least significant figure (6.22 cm x 5.2 cm = 34.43492 cm^2) = 34 cm^2 *Rounding: greater or equal to 5, round up less than 5, round down Addition/Subtraction: least significant figure + one space after decimal! 89.932 g 2.907 ergs - 1.1 g - 0.120 ergs (Only has 2 sig figs + 1) 90.432 g 1.977 ergs 90.4 g 1.98 ergs Example: 90.4 g x 9 = has 3 significant figures, any number without unit measure is infinitely significant Celsius and Kelvin Degrees: - To convert b etwe en Celsius an d Kelvin: Kelvin = Celsius + 273.0 Exam ple: Convert 25.0°C to Kelvin 25.0 + 273.0 = 298.0 K Convert 375 K to d egrees Celsius 375.0 – 273.0 = 102 °C
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     Convert -50°C to Kelvin.  (That's minus 50)    -50.0 +  273 =  223 K Chapter 2 – Objectives Law of constant composition -   States that the composition of a substance is always the same, regardless of how the   substance w   or where the substance is found. *So, whenever we talk about water, we know that there are 2 atoms of hydrogen and 1 atom of oxygen in a   of water. Substance Formula Composition Properties water 2 atoms of hydrogen, 1 atom of oxygen  Clear, colorless, homogeneous liquid that is good for human consumption  hydrogen peroxide 2 atoms of hydrogen, 2 atoms of oxygen Clear, colorless, homogeneous liquid that is considered harmful if consumed by humans (poisonous). Law of Conservation of Matter : - The total mass of materials present after a chemical reaction is the same as the total mass pr   before the action. Mass is always the same and does not change.  Write a word equation: hydrogen +  oxygen  water  Write the masses of each substance given in the question 4 g ? 36 g 
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Use the law of conservation of mass (mass of reactants =  mass of products)  4 +  ? =  36 Solve to find the missing value  ? =  36 - 4 ? =  32 So 32 grams of oxygen were used Law of Multiple Proportions : - If two elements A and B combine to form more than one compound, the masses of B that com   with the given mass of A are in the ratio of small whole numbers. Cathode Ray Tube
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This note was uploaded on 04/29/2008 for the course CHEMISTRY 221 taught by Professor Richardson during the Spring '08 term at Oregon State.

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Chapter 1+ Objectives - Chapter 1 Objectives Significant...

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