Popular in Principles of Chemistry I
Popular in Chemistry
This 10 page Study Guide was uploaded by Sofia Vignolo on Wednesday September 24, 2014. The Study Guide belongs to 111 at a university taught by a professor in Fall. Since its upload, it has received 153 views.
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Date Created: 09/24/14
Chemistry is the study of matter Matter is anything that has mass and occupies space OBSERVATIONS Howrlnuch What is it is there H Omogeneous E9 Are H48 pr39oP8ri6S urlil OrYV N0 p 8 from place loplaoe In CL A sample H 66 rog ereoUS Sonmpl P l L if Slvel ll 393 Pizza 1ling 3nxg PLlG CO Qgnol all hllXPOl rll 7LUrr of 5 6 Jr who ml cog L Vera 01 Fffcu H Sampling is how to differentiate from homogeneous and heterogeneous It39s the sampling that matters If you get the same result from sampling it39s homogenous If you get different results it39s heterogeneous Chemworkshopgmailoom Lab olass starts Sept 9 Q X WC gt Must bring lab manual j L Q 004 M gt Full long pants H30 l 0 Cl gt Full covered shoes gt Safety glasses or googles HO hob lt3 7 W90 W O5 ihe arw llgllf Extensive properties depends on how much matter is being considered gt Values are additive Intensive properties does not depend on how much matter is being considered gt Values are not additive Q 159 4 Halo fig mo 35m 50 75 Physical properties can be measured and observed without changing the composition or identity of a substance Chemical properties can be measured and observed only by changing the composition or identity of a substance Different branches of Chemistry 1 Analytical A Forensic chemistry 2 Biochemistry 3 Inorganic chemistry A Studies the periodic table except Carbon 4 Organic chemistry A Studies Carbon 5 Physical chemistry H3 N C V 0 CH Cobalt is the most important N H3 element in this example so this is Co an inorganic compound even H N l N H 3 though it has Carbon NH3 The Atomic Theory of Matter modern evidence for the existing of atoms comes from the use of the scanning tunneling microscope STM gt This allowed us to see atoms for the first time gt STM was developed in 1981 Postulate of Dalton39s Atomic Theory of Matter 1 Matter consists of indivisible atoms A False Can be subdivided into protons electrons and neutrons 2 All of the atoms of a given chemical element are identical in mass and in all other properties A False Isotopes 3 Different chemical elements have different kinds of atoms and in particular such as atoms have different masses A True 4 Atoms are indestructible and retain their identity in chemical reactions A True 5 The formation of a compound from its elements occurs through the combination of atoms of unlike elects in small whoe number ratios A True The Laws Leading to Atomic Theory 1 The law of conservation of mass A Chemical equations keep track of matter on the atomic scale 2 The law of definite proportions A The proportions between mass of the elements that compose it are fixed independent of the ori in of the compound or it39s mode of preparation a Example synthetic vs quotnaturalquot vitamin C Moog v c ioomgt ioo talc R 3 has more mm vrc O7 QQ Vlt C 1100 rung 100 Jcolb quotV01u V01 38 301 vrtc joomg loo tab SLjrhatI39C gtquot5 9 V39tC 3 The law of combining volumes A When two gases react the volumes that combine do so in the ratio of simple integers M L Sm Darlon H O H O l 6Uj 39 l l QX in 3 15 Qav OilM95 OW5 ELL Come Ved D LiJ2OuTeCormsCmquotO39CLiEaf 4 Avogadro39s Law A Equal volumes of ideal gases at same T and P contain the same number of particles molecules ll 3H3 ea lH3 vol Zval Qvol Avogadro disproved Dalton39s Rule of Simplicity 5 The law of multiple proportions A When two elements form two different compounds the masses can be expressed as a ratio of small whole numbers General structure of atoms Protons positive charge Neutrons no charge 0 Protons and neutrons from the nucleus central part of the atom Electrons negative charge and surround nucleus 0 Condoned to a certain area around the nucleus called orbitals Atomic structure Elements on the periodic table have the same number of protons and electrons so that they are uncharged The charge 16021773 x 10 coulombs Ions are charged and atoms are uncharged neutral M 4 I9 9 Cwbm Mmass number C Zatomic number 2 Z MZneutrons Isotopes same number of protons but different numbers of neutrons igj jsomoeg or Hgalrogen D30 healgt waiterquot lglgUr n39um MASS SPECTROMETER SCHEMATIC Made to separate isotopes through a physical means Used to know the amount of isotopes and molecular weight Molecular formula Used only for covalent species Subscripts specify the exact number of atoms of each element in one molecule of the substance 0 Ex CO2 Empirical formula Subscripts indicate the relative numbers of each kind of atom in the molecule Formula unit Used for ionic species All ionic compounds exist in large crystalline arrays rather than as discrete molecules 0 Ex NaC Molezolarr Empirical formula 33399T gt Molecular formula How to get the empirical formula You can get the total mass from the mass spectrometer Do a decomposition reaction to get the separate elements 0 Combustion burn it 0 What comes back is the weights of each element Now you can get the empirical formula Atomic mass units Aka relative mass units AMU t A W ratios of two masses 0 Has no units because they came from a ratio 0 Amu and gmol are equal but amu39s have no units Avogadro39s number 602 X10 1 mole of ANYTHING Defined as the number of atoms in exactly 12g of C 0 1 mole of C weights exactly 1200000g 0 But a mole of elemental C weights 12011g because it39s a mixture of isotopes Precision vs Accuracy Precision degree of agreement between duplicate experiments Does not necessarily indicate the quotbestquot answer Accuracy degree of agreement with the quottruequot result Types of Error Systematic shift in the measured value from the true value 0 Very good precision may still result Ragfdom due to limitations of the instrument or technique 0 Fourier transforms FD helps to reduce noise quickly with fewer scans Reduces the uncertainty of random errors NMR expectations Actual scan has quotnoisequot MW This quotnoisequot can be canceled by adding different scans and canceling out the quotnoisequot MRI based on nuclear magnetic resonance NMR so it needs FT in order to function quickly since it has a lot of noise Reading a Buret Read from the bottom of the meniscus e 7 SGML It can be L 498 W M 497 W ML 499 496 49 is certain and the decimal is uncertain We only write once decimal because it39s the first one we are uncertain about 4975 is wrong because it has too many decimals The answer can be anything between 49 and 50 with one decimal Significant Figures The last drift in any decimal number is ALWAYS uncertain by definition Rules Significant Figures 1 All nonzero digits are significant 2 Zeros that precede the first nonzero digit in the number are not significant 3 Zeros surrounded by nonzero digits are significant 4 Zeros that follow that last nonzero digit are significant if there is a decimal point 5 If there is no decimal point it cannot be determined if zeros at the end of a number are significant or not Avoid doing this Significant Figures in Calculations A Addition and subtraction P quot a Round off so that the sum or difference has the same A T g number of decimal places as there are in the measurement with the SMALLEST number of DECIMAL PLACES l answer 773 QltgtPgt 77s0l i ampmmmamp9 A Multiplication and division a The proper number of significant figures in the product or quotient equals the SMALLEST number of SIGNIFICANT FIGURES in the measured quantities used as input 2 Ax237 QQWmria5allgtW0 V V ilifr 73 Q 3 wFgt Rules for Rounding Numbers 1 If the first discarded digit is less than 5 the remaining digits are unchanged 2 If the first discarded digit is greater than 5 then the last digit is increased by 1 Jltll dew LPN 391 IVquotHI hucro IMl lU Size relationship of a degree 1 Q Hm Mme as illt 1bFiS5mww3SK Unofficial units 1 lltgt m imtlw 03Z l ot C lOl3Z5M Qm Dimensional analysis C V T lVl tl CJr F or Eg Density s JL0UL Daqg4 oluni
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