General Chemistry Lab

Introduction

General Lab Safety and Housekeeping
- Safety
  
  Safety is of utmost importance in the labs...
- Safety Rules
  
  Please note — if you are not appropriately attired or you behave in an unsafe manner, you will be asked to leave...
- Housekeeping Rules
  
  Clean up after yourself, even though you may be very tired...
Lab Locker Equipment
- Checking into the Lab
  
  Once you have a confirmed space in the lab you may check in to your locker...
- Checking out of the lab
  
  You must check out of your locker when you are done with the class...
- Locker Reference Lists
  
  Beaker, Bottle Weighing, Bottle, Wash, Brush...
How To Use The Glassware
- Cleaning and Drying Glassware
  
  Determine how much time you spend cleaning a piece of glassware by thinking about its use...
How To Use Instruments
- Analytical Balance
  
  The object to weigh must be clean and dry on the bottom, and it must be at or near room temperature...
- The Barometer
  
  The barometer is the instrument with which people read atmospheric pressure...
- Bunsen Burner
  
  Check the rubber tubing on your burner for cracks and possible leaks...
- pH Meter
  
  One of the common measurements in a chemistry lab is of the pH of a solution using the pH meter...
- Hydrogen and Helium Emission Lamps
  
  Please do not leave the lamps on for the entire lab period...
- Use of the Spec 20 Spectrometer
  
  A spectrophotometer is an instrument used to measure the light absorption (transmittance)....
- Calipers (Vernier Scale)
  
  A vernier scale is a device that permits accurately making a reading that lies part way between two values on an instrument such as a barometer or a set of calipers...
- Use of the Voltmeter
  
  Never immerse the clips at the ends of the leads in any solution...
How to Transfer Chemicals
- Solids
  
  It is usually easier to transfer solids to a wide mouthed container such as a beaker...
- Liquid Transfer
  
  Take an appropriately sized, labeled beaker to the reagent shelf...
Data Analysis
- Introduction to Data Analysis
  
  Data analysis requires interpretation of results and comparison to relevant theories (or theoretical values)...
- Uncertainties in Data and Results
  
  Science is interested in repeatable phenomena and in properties that can be measured both qualitatively and quantitatively...
- Significant Figures
  
  Counted and defined quantities are exact and therefore have an infinite number of significant figures...
- Significant Figures in Calculations
  
  You must determine how many significant figures to include when performing a calculation...
- Mean and Standard Deviation
  
  To overcome the effects of random error, an experiment is usually repeated...
- Relative Error and Percent Error
  
  When an average and standard deviation are used...
- Error Propagation
  
  Many times, results are used to calculate the value of some other quantity...
- Making and Interpreting Graphs
  
  Graphs, which show how one variable depends on another, are of great value when determining how different properties affect each other...
- Plots of Nonlinear Relationships
  
  Sometimes the experimental theory suggests that your plot not be so simple as just p against T...
Preparing for the Experiment
- Introduction
  
  The prelab assignment is designed to prepare you for the experiment...
Sample Report
- Introduction
  
  You must share the results of your experiment...
- Report Guidelines
  
  When you write your report, be thorough but concise — long isn't necessarily good....
- Report Examples
  
  A report requires the submission of a copy of your lab notebook from the experiment, which should clearly show your procedure and all the data you collected...
Example Abstacts for a General Chemistry Lab
- Title
  
  Gravimetric Determination of the Solubility Product Constant for Lead (II) Chloride, PbCl₂
- Introduction
  
  In this experiment, the equilibrium exhibited by slightly soluble ionic compounds in water is explored...
- Abstract
  
  Rate the following abstracts from 1 to 5...
Significant Figures
- Significant Figures in Calculations
  
  Values cannot become more precise by mathematical manipulation...
- Significant Figures in Experiments
  
  A measured quantity is usually reported as the value and its associated uncertainty...
- Mathematical Manipulations of Data and Error Propagation
  
  For calculations involving the addition, subtraction, multiplication, and division of two numbers...

Laboratories

Lab 1 - Density Determinations and Various Methods to Measure Volume
- Goal and Overview
  
  This lab provides an introduction to the concept and applications of density measurements...
- Suggested Review and External Reading
  
  Data analysis introduction, textbook information on density
- Introduction
  
  The density, ρ, of an object is defined as the ratio of its mass to its volume...
- Equipment List
  
  cylinders: brass, aluminum, mixed brass/aluminum, and hollow...
- Procedure
  
  NOTE: IF YOU WORK WITH ANOTHER SET OF PARTNERS, MAKE SURE YOU RECORD ALL DATA...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 2 - Determination of the Empirical Formula of Magnesium Oxide
- Goal and Overview
  
  The quantitative stoichiometric relationships governing mass and amount will be studied using the combustion reaction of magnesium metal...
- Suggested Review and External Reading
  
  Data analysis introduction (online), reference materials, Textbook information on ionic compounds and empirical formulas
- Background
  
  A great deal of chemical knowledge has been amassed by using simple combustion experiments conducted with crucibles, burners, and balances...
- Experimental Notes
  
  Equipment List: Safety goggles, Magnesium ribbon, Mg, Balance (to 0.0001 g), Ring stand, Bunsen burner, Ring support/clay traingle,...
- Procedure
  
  Your TA will demonstrate. Ask questions as needed...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 3 - Heats of Transition, Heats of Reaction, Specific Heats, and Hess's Law
- Goal and Overview
  
  A simple calorimeter will be made and calibrated...
- Suggested Review and External Reading
  
  See reference section; textbook information on calorimetry and thermochemistry
- Background
  
  The internal energy, E, of a system is not always a convenient property to work with when studying processes occurring at constant pressure...
- Experimental Notes
  
  There are two possibilities for your calorimeter setup, but both require the same procedure....
- Procedure
  
  This is the experiment discussed in Example 1...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 4 - Determination of the Amount of Acid Neutralized by an Antacid Tablet using Back Titration
- Goal and Overview
  
  Antacids are bases that react stoichiometrically with acid...
- Suggested Review and External Reading
  
  data analysis and reference material; relevant textbook information on acids and bases
- Background
  
  Acid-base reactions and the acidity (or basicity) of solutions are extremely important in a number of different contexts - industrial, environmental, biological, etc...
- Procedure
  
  Follow the procedure outlined for buret usage. Be sure your buret is clean and the stopcocks are firmly seated...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 5 - Characterization of an Unknown Acid
- Goal and Overview
  
  The titration curve of an unknown weak acid with a strong base will be measured using a pH meter...
- Suggested Review and External Reading
  
  reference section; relevant reference and textbook information on weak acids and bases
- Background
  
  A weak acid is one which does not completely dissociate in water solution...
- Procedure
  
  Caution: You are working with unknown organic compounds. Handle them with caution and wash them off your skin...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 6 - Quantum States for the Visible Hydrogen Atomic Emission Spectrum
- Goal and Overview
  
  The relationship between color, wavelength, and frequency of visible light will be determined using a Spec 20 spectrometer...
- Suggested Review and External Reading
  
  data analysis and spectroscopy information; relevant textbook information on quantum theory
- Background
  
  The study of the interaction of light with matter is called spectroscopy...
- Procedure
  
  This part of the experiment is not designed to take a lot of time...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 7 - Determination of the Molar Mass of an Unknown Solid by Freezing Point Depression
- Goal and Overview
  
  In the first part of the lab, a series of solutions will be made in order to determine the freezing point depression constant, K_f, for cyclohexane...
- Suggested Review and External Reading
  
  Reference information on thermodynamics; data analysis; relevant textbook information
- Background
  
  If a liquid is at a higher temperature than its surroundings, the liquid's temperature will fall as it gives up heat to the surroundings...
- Procedure
  
  Caution: Cyclohexane is highly flammable. No flames are permitted in the lab...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 8 - Acids, Bases, Salts, and Buffers
- Goal and Overview
  
  Hydrolysis of salts will be used to study the acid-base properties of dissolved ions in aqueous solutions...
- Suggested Review and External Reading
  
  data analysis review; relevant textbook information on acids, bases, salts, and buffers
- Background
  
  Brønsted-Lowry acids are proton donors and bases are proton acceptors...
- Procedure
  
  Caution: You are working with acids and bases. Handle them with caution and clean up spills...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 9 - Determination of Allura Red Concentration in Mouthwash
- Goal and Overview
  
  The spectral profile of allura red, or red dye #40, will be measured using a Spec 20 spectrometer...
- Suggested Review and External Reading
  
  reference material on spectroscopy and dilution; textbook information on spectroscopy
- Background
  
  The study of the interaction of light with matter is called spectroscopy...
- Procedure
  
  Be sure to use the same Spec 20 for the entire experiment...
- Reporting Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 10 - Solubility Product for Calcium Hydroxide
- Goal and Overview
  
  A saturated solution of Ca(OH)₂ will be made by reacting calcium metal with water, then filtering off the solids...
- Suggested Review and External Reading
  
  reference information on equilibrium and solubility; relevant reference and textbook information on solubility, acids, and bases
- Background
  
  Whenever solid calcium hydroxide, Ca(OH)₂ (commonly known as lime), is present in water, it dissolves according to...
- Procedure
  
  Check out any required equipment from the stockroom (or borrow necessary items from the reagent bench)...
- Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 11 - Spectroscopic Determination of an Equilibrium Constant
- Goal and Overview
  
  The reaction of iron (III) with thiocyanate to yield the colored product, iron (III) thiocyanate, can be described by the following equilibrium expression...
- Suggested Review and External Reading
  
  Reference information on spectroscopy (see Lab 9) and dilutions; relevant textbook information on spectroscopy and equilibrium
- Background
  
  This experiment investigates the equilibrium established by the reaction of the iron (III), Fe³⁺, and the thiocyanate, SCN⁻, ions...
- Procedure
  
  Using a 10 mL graduated cylinder, measure out approximately 2 mL of 2 × 10⁻³ M NaNO₃ and put it in a test tube...
- Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 12 - Rate Properties of an Iodide Oxidation Reaction
- Goal and Overview
  
  The rate law for the reduction reaction of peroxodisulfate (PODS) by iodide...
- Suggested Review and External Reading
  
  relevant reference and textbook information on kinetics and dilutions
- Background
  
  Thermodynamics describes the equilibrium phases and concentrations of reactants and products under a given set of conditions...
- Procedure
  
  Note: Wash your glassware before you use it, and return it clean. Dedicate one pipet to each solution (don't mix and match)...
- Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 13 - Electrochemistry and the Nernst Equation
- Goal and Overview
  
  A voltmeter is used to study the relative reduction potential of various metals and the concentration dependence of voltage in concentration cells...
- Suggested Review and External Reading
  
  relevant reference information and/or textbook information on thermodynamics, electrochemistry, equilibrium, and free energy
- Background
  
  The primary measurement in electrochemistry is the voltage (V) of an electrochemical cell...
- Procedure
  
  Please use small volumes of solution to reduce the cost of buying chemicals and the problems with waste disposal...
- Results
  
  Complete your lab summary or write a report (as instructed)...
Lab 14 - Determination of Amount of Vitamin C in a Commercial Product by Redox Titration
- Goal and Overview
  
  The amount of ascorbic acid (vitamin C) in a commercial product will be determined by using redox titration of vitamin C with 2,6-dichloroindophenol (DCP)...
- Suggested Review and External Reading
  
  introduction to data analysis; textbook information on titration and redox
- Background
  
  Vitamin C is known to be important in the human diet. In the mid-1700's it was discovered that vitamin C contained in citrus fruits prevented scurvy...
- Procedure
  
  Caution: Do not fill burets on the work-bench. Always keep all chemicals below eye level...
- Results
  
  Complete your lab summary or write a report (as instructed)...