Chemistry 1020 Dr Plath first exam notes
Chemistry 1020 Dr Plath first exam notes CHEM 1021
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This 13 page Study Guide was uploaded by Hanin Abu Amara on Thursday January 7, 2016. The Study Guide belongs to CHEM 1021 at University of Colorado taught by Dr. Plath in Fall 2015. Since its upload, it has received 57 views. For similar materials see Introductory Chemistry (CHEM 1021, Dr Plath) in Chemistry at University of Colorado.
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Date Created: 01/07/16
Into to Chemistry Exam #1 Notes 01/07/2016 ▯ Define Chemistry: Study of matter ▯ ▯ Matter Physical matter of universe Anything that occupies space has mass o Book, body, air Mass is a measure of the amount of matter in an object Weight is affected by gravity BUT Mass IS NOT ▯ ▯ Classifying Matter 2 types: mixtures or pure substances based on chemical composition ▯ ▯ Pure Substance Same composition all throughout Doesn’t vary from sample to sample Can’t be physically separated o Water, gold, etc. Break down to elements and compounds ▯ ▯ Elements Smallest category One type of atom o Smallest unit of element if you break it down its all the same cannot be broken down into any simpler substance o gold, carbon, graphite, copper, helium, mercury some elements exist as diatomic elements o BrINClHOF Br2, I2, N2, Cl2, H2, O2, F2 Elemental molecules ▯ ▯ Molecules 2 or more atoms that are chemically bound o same or different atoms behave as an independent unit o move all together ▯ ▯ Compound 2 or more different elements broken down by chemical means o water H2O 2H and 1O o Carbon dioxide CO2 1C and 2O o Methane CH4 1C and 4H Subscripts indicate how much of each element is present ▯ All compounds are molecules ▯ ▯ Periodic Table Columns = groups (up and down) Rows = periods (left and right) Types of grouping = metals, non-metals, metalloids o Metals are luster (shinny), conduct heat and electricity o Non-metals = dull, do not conduct electricity o Metalloids = not as shinny, low conduction ▯ Main group = first 2 group and last 6 ▯ Transition metals = middle 10 groups ▯ ▯ ▯ ▯ ▯ ▯ ▯ ▯ Mixtures 2 or more elements/ compounds 2 or more pure substances physically intermingled you cant take something out of it two types o homogenous consistent all through no visible boundaries called a solution water solution is aqueous solution coffee sweetened with sugar Kool-Aid salt water all the same phase o heterogeneous no consistent composition throughout / within the solution has one or more visible boundaries between the components air, vegetable broth, cement ▯ ▯ chart of classification of matter ▯ matter can it be physically separated? If no it’s a pure substance. Can it be decomposed chemically? o if no its an element. Can it conduct electricity? If no it’s a non-metal If yes it’s a metal o If yes it’s a compound If yes it’s a mixture. Is it homogenous? o If no it’s a heterogeneous mixture o If yes it’s a solution ▯ ▯ Concept Test: ▯ Sand collected at the beach is classified as? ▯ Homogenous mixture ▯ Pure substance ▯ Compound ▯ Heterogeneous mixture ▯ ▯ State of Matter Three states of matter o Solid: physical state characterized by definite shape and definite volume o Liquid: physical state characterized by an indefinite shape and a definite volume Takes shape of container o Gas: physical state characterized by an indefinite shape and volume Depends on temperature and pressure under which the observation is made ▯ ▯ Concept Test: ▯ On a certain planet “cijue” has a definite volume, but its shape varies from container to container. Cijue is best classified as… Solid Liquid Gas ▯ ▯ Properties of matter Kinds of matter differentiated by their properties Properties are the distinguishing characteristics of a substance They are used for identification and classification Each chemical has unique properties Two types of properties o Physical properties Characteristic of a substance that can be observed without changing the substance into another substance Temperature, mass, structure, color, taste, odor, boiling point, freezing point, heat capacity, hardness, conductivity, solubility, density. (look at slide 16 of August 28 for elaboration) Physical change is when the physical properties change and chemical composition remains the same. Gas to liquid is condensation Liquid to solid is freezing Solid to gas is sublimation Gas to solid is deposition Solid to liquid is melting Liquid to gas is vaporization o Chemical properties Characteristic of a substance that describes the way the substance undergoes or resists change to form a new substance. Iron gets rusty, carbon burns, silver tarnishes, nitroglycerin explodes, neon does not react with anything. Change involved interaction of one substance with another. Some changes takes place when substance breaks down/ decomposes. Chemical changes is when one or more substance are converted into one or more new substances. ▯ Temperature Fahrenheit o Water boils at 212 o Room temp. 77 o Water freeze 32 o Lowest possible temperature -460 Celsius o Water boils at 100 o Room temp. 25 o Water freeze 0 o Lowest possible temperature -273.15 Kelvin o Water boils at 373.15 o Room temp. 298.15 o Water freeze 273.15 o Lowest possible temperature 0 Temperature Conversion o C to K Tk= Tc + 273.15 o C to F Tf= (1.8)Tc +32 o F to C Tc= (Tf-32)/1.8 ▯ Density Ratio of an object’s mass to its volume =mass/volume common units (liquids) g/mL or g/cm^3 density is useful in conversions will it float or sink ▯ ▯ Concept Test ▯ When a small piece of metal is placed inside a graduated cylinder initially containing 10 mL of water, the water level rises to 13.7 mL. If the mass of the metal is 5.68 g, what is its density? 0.41g/mL 0.24 g/mL 1.5 g/mL o D=mass of object/volume of object o Change in volume: 13.7mL-10mL=3.7mL o Mass of object: 5.68g o Density=5.68g/3.7mL=1.5mL 2.4 g/mL ▯ ▯ Energy physical and chemical changes involve energy is capacity to do work/ transfer heat o work: energy used to cause an object with mass to more against a force. Climb stairs Lift box o heat: flow of energy caused by a temperature difference hot coffee cold hands o heat and work are ways to exchange energy objects posses energy Types of energy o Kinetic energy: energy of motion Increases with temperature Thermal energy is type of kinetic energy Associated with temperature of an object o Potential energy: stored energy that results from the attractions and repulsions an object experiences in relation to other object. Increases with position Chemical energy is type of potential energy Potential of chemical substance to undergo a transformation through a chemical reaction. o Potential and kinetic energy can be interconverted Units of energy o Joule (J) defined as (1kg m^2)/s^2 1 J is equivalent to the energy associated with an average sized apple falling ~ 3 feet o Calorie (cal): amount of energy required to raise the temperature of 1 gram of water by 1C 1Cal=4.184 J ▯ Concept Test ▯ All of the following are examples of kinetic energy except: Running a marathon Sitting on the couch Dancing to music Hand washing your car ▯ ▯ Scientific Method Observations (find patterns, trends and laws) Hypothesis (revised if experiment does not support) Experiment (revised if experiment does not support) Model (theory) Further experiment ▯ ▯ Scientific Notation Expresses number in compact form Non-zero digits ALWAYS significant Leading zeros are NOT significant Confined zeros are ALWAYS significant Trailing zeros are significant only when there is a decimal point ▯ ▯ Accuracy Vs. Precision Accuracy indicator of how close a measurement comes to the true value Precision indicator of how close a series of measurements of the same objects ▯ ▯ Uncertainty Measurement There is no such thing as exact measurement Estimate digit is said to be uncertain Last digit is always certain ONLY ONE uncertain digit recorded ▯ ▯ SI Base Unit Mass kilogram (kg) Length meter (m) Time seconds (s) Temperature kelvin (K) Amount of substance mole (mol) Prefixes: o Tera trillion o Giga billion o Mega million o Kilo thousand o Deci tenth o Centi0.001 o Milli 0.0001 o Micro0.000001 o Nano 1x10^-9 o Pico 1x10^-12 Conversion unit general approach: o Given unit x (desired unit/given unit) = desired unit ▯ ▯ Law of Mass Conversation Total mass of substances does not change during a chemical reaction. ▯ ▯ Law of definite proportions No matter the source, a particular compound is composed of the same elements in the same parts by mass. ▯ ▯ Law of multiple proportions If elements A and B react to form two compounds, the different masses of B that combine with fixed mass of A can be expressed in a ratio of small whole numbers ▯ ▯ Dalton’s Atomic Theory All matter consists of very small particles called atoms Atoms of an element are identical in mass and in chemical composition, and are different from atoms of other elements. Atoms are not created or destroyed in a chemical reaction Compounds result from the chemical combination of a specific ration of atoms of different elements. ▯ ▯ ▯ ▯ ▯
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