Chem 1070 Week 1 Notes
Chem 1070 Week 1 Notes CHEM-1070-40
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This 3 page Class Notes was uploaded by Dkrefft on Saturday August 29, 2015. The Class Notes belongs to CHEM-1070-40 at Tulane University taught by Lopreore, Courtney in Fall 2015. Since its upload, it has received 663 views. For similar materials see General Chemistry I in Chemistry at Tulane University.
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Date Created: 08/29/15
CHEM 1070 826 Cha pter One Chemistry the study of mater and the change it undergoes Matter anything that takes up space and displays the properties of mass and inertia Physical properties do not entail a compound changing Color malleability Water freezing is a physical change Chemical changes entail a change in property Ability or inability of sample to under go a change in composition ie inability of AU to react with HCI Chemical reactions convert matter into something with a new composition like the burning of papen Classifications of matter atoms molecules Atoms make up elements A chemical compound is two or more elements joined together They can be the same element A molecule is the smallest unit of that compound that has the same proportions as consistent atoms Diatomic elements are elements that don t exist alone except as an ion They are 0 H2 02 F2 Br2 l2 N2 Cl2 OOOOOO Substances are uniform from one sample to another Elements and compounds whose composition and properties are uniform throughout a given sample and from one sample to another Mixtures can vary within a sample and from one sample to another both physically and chemically o Homogeneous solution uniform in composition chemical properties and properties throughout ie air sea water gasoline o Heterogeneous composition and properties can vary from one part of the sample to another ie orange juice with pulp Separating mixtures o Filtration separates solid from a liquid 0 Distillation pure liquid is condensed from vapor of boiling solution 0 Chromatography this takes advantage of different compounds and their ability to adhere to surfaces in different ways States of matter solid liquid gas plasma Metric system is SI 0 TK TC 27315 Density massvolume and gml Uncertainties in measurements 0 Systematic errors Built in inherent ie cheap old scales 0 Random errors Limitations in experimenter s ability or skill 0 Precision getting to reproduce the same effect every time 0 Accuracy how close you are to an accepted value 0 Significant figures 0 All non zero digits are significant 0 Zeroes are significant except when preceding the decimal or following the decimal and preceding the first non zero digits 0 When multiplying use the least amount of sig figs In the quantities you re multiplying 0 01 1 significant figure 0 0001 1 significant figure 0 100 3 significant figures 0 7500 ambiguous and infinite amount of significant figures 0 75 x103 2 significant figures 0 750 x103 3 significant figures 0 7500 x103 4 significant figures 0 for multiplying and dividing with significant figures answer in the least amount of significant figures of one of the numbers 0 1479cm x1211cm x 505cm 904cm 0 additionsubtraction use the smallest number of significant figures after the decimal point 0 1502 99860 3518 100045 counting conversions have unlimited sig figs unless it s something like 1 in 254 cm 0 you can go any way with a conversion factor 1 in 254 cm 254 cm 1 in desired unit gwen unit x f deSlred unit gwen unit the given unit cancels Chapter Two law of conservation of mass what you have before a reaction is the mass after the reaction Matter is conserved 0 Example 1 A 712 g sample of magnesium is heated with 180g of Bromine All of the bromine is used up and 207g of MgBr2 is the only product What mass of Mg is left unreacted 180712207x 892207 685g constant proportion all samples of a compound have the same composition 0 Sample A 1000 g Sample B 2700g H1119 O8881 1119gH 3021gH 8881g O 2398g O 0 Example 2 When 0455g of Mg reacts with 2315g 02 0755g of MgO is obtained Determine the mass of Mg contained in 0500g MgO 0455 M xM 0 Set up a proportion g 0755g MgO 0500 MgO x 0301g Mg You may not need all of the information you re given Ask yourself 0 What is the problem asking for o What do you need 0 What can you ignore Dalton s Atomic theory atoms cannot be created or destroyed during a chemical change ie oxygen can t turn into nitrogen All atoms of an element are alike in mass and other properties but elements differ from one another In each compound elements combine in simple numerical ratios Always whole numbers H20 002
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