Chem Lab Final Study Guide PDF

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Chem Lab Final December 4, 2017 ●

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Quantitative vs. Qualitative ○ Quantitative data: ■ How much is in a sample ○ Qualitative data: ■ What is in a sample ○ Qualitative Analysis: ■ A chemical separation method designed to isolate and identify ions in an unknown sample ○ Quantitative Analysis: ■ Determination of the amount or concentration of a substance in a sample What is density? ○ Density: ■ the ratio between mass and volume ○ What are the units of density? ■ Mass is measured in : grams or kilograms ■ Volume is measured in: liters, cubic centimeters or millimeters ○ In which labs do we rely on density? ■ Measurement in and out lab (3.1) ○ What was the math involved? ■ Density= mass/volume ○ How can you tell if one material is denser than another? ■ The less dense material tends to float on top of the more dense What are the types of glassware that we have used in the lab? ○ Go through lab notebook and find glassware that was used in the lab, know how to use them: ■ Beaker ( 100 , 250 , 400 ml) ■ Graduated Cylinder ( 10, 25, 100 ml) ■ Filter flask ( 50 ml) ■ Test tube ■ Watch glass ■ Short stem glass tunnel ○ Be able to do the same for the instruments used as well ■ Separatory Funnel & Stopcock: Used in Calculating Your Jitters, helps titrate a certain amount of liquid into a solution ■ Burret: helps measure the volume of a gas or liquid ( Acid and Bases: Titration) ■ Ph paper: helps identify the pH of a solution (Acid and Bases: Titration) ■ Centrifuge: Spins a test tube around until the parts are all separated (Heavy Metal : Getting the Lead Out)

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Heating plate : helps boil the water faster ( Under Pressure : Clouds/Effusion of CO2 ) Ring Stand and clamp: helps hold beakers/thermometers up right so you can get accurate measurements ( a lot of experiments use this) Spectroscope: helps us see the visible light spectrum ( visible spectrum)

■ Calorimetry ○ Calorimeter: device used to measure the amount of heat ○ What is delta T and how do you find it? ■ Delta T is the difference between the final and initial temperature, you find it by subtracting the two temperatures from one another ○ What do temperature graphs tell you? What types are there? ■ There are two types of temperature graphs, a heating curve and a cooling curve, which are used to display a delta T which will later be used to find the heat of the surroundings. ○ Know the difference between endothermic and exothermic ■ Endothermic : Heat absorbing (q is positive) ■ Exothermic: Heat releasing (q is negative) ○ What is the system? ■ Part of the universe that is being studied ○ What are surroundings? ■ Rest of the universe that interacts with the systems What is the visible spectrum? ■ Visible spectrum: p  ortion of the electromagnetic spectrum that is v isible to the human eye. ○ At what wavelengths do each of the colors appear? ■ 400: purple ■ 500: blue ■ 600: yellow ■ 700: red ○ Relationship between wavelength and frequency, and the equation that shows this relationship. ■ Frequency= Speed of Light/ Wavelength How do you use the scales in the lab? ■ First you zero the scale, place substrate in weigh boat, then place weigh boat on scale. Be able to determine the relationship that the trendline gives you ■ Once you have the slope you are able to plug in a point on the graph to get the slope What are the solubility rules, the ones listed on blue door? ○ Solubility: the ability of a compound to dissolve in another substance ■ Solubility Rules: ● All compounds that contain Group 1 are soluble ● All comps that have NH4^+ (ammonium) are soluble

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All compounds that contain NO3^- (nitrate) or C2H3O2- (acetate) are soluble ● All compounds that contain a group VII element (halogen) are soluble ○ EXCEPT halides that contain: Ag+, Hg+, or Pb2+ ● All compounds that contain sulfate ion (SO4^-2) are soluble ○ EXCEPT those that contain Ba+2, Sr+2, or Pb+2 ● All the other compounds are INSOLUBLE ○ How does pH affect solubility? ■ If you increase pH, solubility decreases; if you decrease pH, solubility increases. They are inversely related. ○ How did we separate metals from solution in lab? ■ Strong acids/bases= those that completely dissociate in water, as in they donate all of their Hydrogen ions/protons(acids) or hydroxide ions(bases). ■ Acid-base reactions ● Acid: substance that dissolves in water to yield H3O+ (hydronium ions) ○ Strong acids: HCL ● Bases: a substance dissolved in water to yield OH (hydroxide ions completely dissolved in water ○ Strong bases: NaOH, Ba(OH2), Ca(OH)2 What is electronegativity? ○ Electronegativity: ■ An element's ability to pull electrons towards itself when participating in a covalent bond ○ What is the trend of electronegativity across the periodic table? ■ Electronegativity increases as you move from left to right and from bottom to top ○ Based on electronegativity can you tell if a reaction will occur? How? ■ The more electronegative the element the more likely it is to react, so an element with a higher electronegativity is considered more “reactive” than that with a lower. THis can be used to help predict whether or not a reaction will occur, higher= more likely, lower= less likely. Be able to assign oxidation states to elements in a compound ○ Rules for Oxidation numbers: ■ Elements alone have oxidation # of 0 ■ Monatomic atoms have the same oxidation # of their charge ■ Neutral molecules must equal 0 ■ In a polyatomic ion, the oxidation # is equal to the charge of the ion ■ Fluorine is the most electronegative element and always has an oxidation # of -1. ■ Oxygen always has ox# of -2, except for peroxides (H2O2) hydrogen peroxide

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■ Group 1A: +1 ■ Group 2A: +2 ■ Group 7: -1 (unless oxygen is involved) ■ H: + with non metals and - with metals Examples of soluble v insoluble: ■ AgI → insoluble ■ Cesium Chloride → soluble ■ Li_3PO_4 → soluble ■ Strontium carbonate → insoluble ■ Pb(CH3CO2)2 → Soluble

What is reduction? ■ Gain of electrons ■ Ex: Oxidation # goes from +5 to -1 ○ What is oxidation? ■ Loss of electrons ■ Ex: Oxidation # goes from -1 to +5 ○ What does Redox refer to? ■ It refers to a r eaction in which the reactants and products demonstrate a change in oxidation state What is the LD50? ■ The amount one can ingest of a substance before it kills 50% of a test sample How do you determine ○ Mass % ■ Mass percent = (molar mass of element/ total molecular mass of the compound) X 100 ○ % Error ■ Percent Error= [(|Exact Value - Expected Value|) / Exact Value] X 100 ● | | = absolute value ○ Moles of element given know volume, reaction equation, molarity ○ Surroundings= Q of system ○ Valence electrons of an element ○ Molecular geometry of a compound Review all equations we used and know how to apply them ○ Slope: (y-y1) / (x-x1) ○ Mass % = [(mass of solute)/(mass of solution)] X 100 ○ LD50 caffeine: (X mg caffeine) / (Kg of Body Mass) ○ Molarity: M = (mol solute) / (L solution) ○ pH = -log[H+] ○ POH = -log [OH-] ○ Combined Gas Law = [(P1V1) / T1)] = [(P2V2) / T2)] ○ Ideal Gas Law: PV = nRT ■ P = pressure

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■ V= Volume ■ n= number of moles in a molecule ■ T= Absolute Temperature (K) ■ R = Gas constant = 8.314 j/K OR 1.985 cal/ degree C Rate of Effusion: (1 / √M olecular W eight) (molecular weight = g/mol)

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[ (Rate of Effusion 1) / (Rate of Effusion 2) ] = [ (

√M olecular W eight1 ) / (

√M olecular W eight 2 ) ○ ○

Q surroundings = - (Q systems) m x c x ΔT = -  (m x c x )

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Q surroundings = m x c x ΔT ■ M = Mass of solution ■ C = Specific Heat (specific heat of water = 4.184 J/g ° C) ■ Δ T = Change in temp= (T final - T Initial) Partial Pressure (Element x) = [ ( Nx / Ntotal ) ] X Ptotal Force (energy) = K [ ( Q1 X Q2 ) / r ] ■ K = Proportional constant = 2.31 x 10^-28 J x M ΔH(solution) = (Q solution / n)

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■ N = number of moles in a solute V = ( c / λ) ■ V = frequency (Hz) ■ λ = wavelengths (m) ■

C = Speed of light = 3.0 x 10^8 m/s

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