CHEM 1LC Final
Procedures Lab 3:
FS: --> find lambda max of crystal violet -->use dilution equation to create four dilutions NaOH --> mix and immediately place cuvette in labquest --> create time vs absorbance (concentration) graphs with each integrated rate law -------------------------------------------------- OI: --> find lamda max food dye -->use dilution equation to form four dilutions of NaOCl -->use volumetric pipette to measure 5mL of NaOCl and 5mL of food dye --> quickly transfer to cuvette and record data --> make integrated rate law graphs
What are three corrosives?
acids, bases, oxidizers
Dilution equation
(MconcVconc = MdilVdil) used when diluting to volume
What do the colors of the fire diamond correspond to:-Blue-Red-Yellow-WhiteWhat number on the scale corresponds to most dangerous?
-Health-Fire-Reactivity-Special 4 is most dangerous
What is the breakthrough/permeation time for nitrile gloves?
1 min
What is the appropriate sig figs for using an erlenmeyer flask/beaker?
1-2 the number of significant figures associated with a volume of liquid measured with the glassware above is very small,
.The sodium bicarbonate is included because it is a mild, cheap, and convenient method to neutralize an acidic spill. What would be a good reagent to use in the event of a chemical spill involving a base?
A good reagent to use in the case of a chemical spill would be a weak acid, such as citric acid The spill should also not be over sized The sodium bicarbonate is a good neutral base to dilute an acid before it can be absorbed and properly cleaned up.
calibration curve
A graph showing the value of some property versus concentration of analyte. When the corresponding property of an unknown is measured, its concentration can be determined from the graph.
What does acid build when it comes in contact with the skin?
Coagolum (builds up protective layer)
Imagine a hypothetical situation in which 250 mL of diethyl ether (SDS) has spilled inside of a chemical fume hood onto a hot plate. The heating element is off, but the hot plate is plugged in and stirring. Discuss the risks associated with this situation (location, size, compound spilled, and external hazards), and then explain how this spill should be managed.
Diethyl ether is a highly volatile and exhaustible substance and because hot plate is still on while the heating element is off, it poses an external danger. Because the spill is only 250mL, the spill is manageable by unplugging the hot plate to , put a barrier around the spill, properly contain the spill, and dispose in spill bin.
Procedures Lab 4:
FS: -->pH probe test with pH buffer 7 -->take pH of weak acid/base -->use ratio to make 50mL of buffer -->measure pH and use HH equation to find expected pH for buffer and % error to determine accuracy of equation -->chose titrant based on buffer (acetic acid=NaOH) and gather 25mL of two different concentrations -->put in buret and titrate -->gather volume added and pH to -------------------------------------------------- OI: --> find pH of gatorade with probe --> use dilution equation to find concentration of titrant from stock solution -->titrate Gatorade with both concentrations of appropriate titrant -->use HH equations to find ratio and find buffer capacity of Gatorade
Data Analysis/Conclusions Lab 2:
FS: create concentration vs absorbance graphs to --------------------- OI:where the max. absorbance appeared=color opposite color of solution/one max.=one dye present lamda max of red dye and gatorade same =presence of red 40
Purpose of Lab 3:
FS: determine the optimal conditions to observe crystal violet hydroxylation kinetics I hypothesize that the least diluted solution will produce the most accurate time vs concentration graph demonstrating the kinetics of a first order reaction because the .01M concentrated NaOH and crystal violet has the least amount of molecules the solvent has to interact with and break down, which will produce a slower reaction to allow us to observe the kinetics and first order reaction rate depends directly on concentration, which is the linear relationship I predict the reaction will produce. -------------------------------------------------- OI:determine the best concentration of NaOCl to observe kientics of bleaching food dye/reaction order of bleaching
Data Analysis/Conclusions Lab 4:
FS: form titrant volume vs pH graph determine buffer capacity and equivalence point Buffer Capacity: β = Δmolestitrant/ ΔpH to find which concentration of titrant the buffer capacity is greatest that the buffer solution could resist change in pH -------------------------------------------------- OI: form volume of titrant vs buffer gatorade pH to determine pKa and ratio the least concentrated NaOH best to find buffer capacity and ratio because more data points to work with higher buffer capacity with that titrant more accurate titration curve
Purpose of Lab 4:
FS: measure pH as a function of titrant volume to determine buffer capacity/accuracy of Henderson Hasselbach equation hypothesized that strongest acids dissociate completely -------------------------------------------------- OI: determine the buffer capacity and HA/A- ratio of Gatorade
Procedures Lab 2:
FS: obtain food dye and look at absorbance spectrum make 5 dilutions mix in volumetric flask (use volumetric pipette to transfer dye and DI water) and then use cuvette to find max absorbance (make sure to find lambda max of stock first and input in labquest) --------------------- OI:fill cuvette with gatorade and measure with Red 40 or food dye color lamdba max and use the equation from last lab to find x or concentration of dye in gatorade with the y or absorbance found Absorbance=(slope)(concentration)+ y intercept
Purpose of Lab 2:
FS:The objective of this lab is to create stock solutions using volumetric glassware and understand the amount of absorbance that each respective concentration will yield using a Beer's Law plot. hypothesized the highest concentrated would have the highest absorbance ----------------------------------- OI: determine the type of dye and its concentration in a given sample of gatorade
Data Analysis/Conclusions Lab 3:
FS:The optimal condition to observe the kinetics of crystal violet reacting with NaOH would be the solution with 0.01M concentration of NaOH because it yielded the highest R^2 value of .999/first order graph produced a straight line -------------------------------------------------- OI:lowest concentration best to observe kinetics slower and first order
Basic Procedures Lab 1:
FS:This objective can be accomplished by analyzing a calibration curve from each glassware from measuring the concentration and density of a four sucrose (.25g, .50g, 1.0g, 1.5g) solutions, with sucrose as the solute and deionized water as the solvent. ------------------------------------ OI:This objective can be accomplished by measuring the mass (g) of a given gatorade sample using the volumetric flask and graduated cylinder, applying the specific density equations from last lab calculate the sample grams of sucrose, and utilizing the percent error equation to determine the accuracy of the nutrition label.
How should you put on/remove lab coat and gloves?
From the inside surfaces. Avoid touching the outside because they could be contaminated
GHS: Gas container
Gas cylinder: gases stored under pressure ammonia/liquid nitrogen
Which of these methods seemed to be the least dangerous and most effective for extinguishing the fire? What factors did you consider in making this decision? (safety moment #3 part 2)
Out of the three methods of removing oxygen by placing a beaker over the candle, blowing the fire out to disrupt the oxygen flow, establishing a barrier, or using water to put out the fire, removing oxygen by placing a beaker over the candle was the least dangerous and most effective. We decided this method was the best because it did not involve adding an external substance such as water, risking close contact to the fire, or increasing the fire in any capacity.
PASS. What does it stand for?
P- pull A- aim S- squeeze S- sweep The acronym for fire extinguishers
What can the sponge represent in the safety moment where we pour acid on it?
Since the sponge is made of organic materials, it can be representative of human skin
digital balance use steps
Step 1: Container Choice & Preparation Step 2: Turning On & Taring (press bar once and wait for seconds to display 0.00g) place empty container and press tare Step 3: Recording the Mass (grab reagent bottle, open draft shields, cap flasks with lqiuid, close shields, record with appropriate sig figs) Step 4: Clean Up
What do you do if you are on fire?
Stop, drop, and rollUse lab coat or blanketOnly use shower if it is close
GHS flame over circle
oxidizers: chemicals that facilitate burning/make fires burn hotter and longer acidic acid
What are graduate cylinders used for?
provide a flexible/ more accurate way to measure liquid volume
Main Conclusions/Analysis Lab 1:
Use Mass of Solution= (mass of glassware +solution) - (mass of glassware) to find mass of solution and then density= grams of solution/milliliters of solution to find moles of sucrose concentration=moles of sucrose/liters of solution graph concentration vs density for each glassware the volumetric flask more precise because highest R^2 ----------------------------------- OI:The graduated cylinder is the most accurate because it had the lowest percent error following our calculations and is most comparable to the nutrition label.
What is a volumetric flask used for?
accomodate tight fitting glass stopper/plastic cap/used to make solutions of a known concentration (stock/standard solutions) remember pre-rinse with solvent calibration mark is single gradation line to indicate exact volume of the flask
GHS symbol: skull meaning
acute toxicity: substances are poisonous includes highly concentrated acids--> severe toxic effects
GHS exclamation mark
an immediate skin, eye, or respiratory tract irritant/narcotic CITRIC ACID CRYSTAL VIOLET OXALIC ACID hydrochloric acid ammonium chloride
if volume of the liquid does not need to be determined accurately use what glassware/ use for liquid transfer
beaker/Erlenmeyer flask volumes held are approximations
what are volumetric pipettes used for?
deliver a single fixed volume of a liquid at a specified temperature remember do not blow any liquid remaining inside never use to transfer heated solutions/incompletely dissolved solids
Purpose of Lab 1:
determine the more precise glassware out of a graduated cylinder, volumetric flask, beaker, and erlenmeyer flask determine if the mass of sugar in gatorade comparable to the nutrition label
GHS: fish/tree symbol
environmental hazard: chemicals toxic to aquatic wildlife lead, mercury, cronium BLUE dye
What are the 4 methods of extinguishing a fire?
exclude air (removing oxygen), remove fuel, remove heat (pour water), interruption by extinguisher chemicals
GHS: bomb
exploding bomb=explosives including organize peroxides and highly unstable material at risk of exploding even without exposure to air
GHS flame
flammable materials/substances liable to self ignite when exposed to water/air/which emit flammable gas
What are the sig figs assigned to volumetric glassware?
four
What 4 things are required to propagate a fire?
fuel, heat, oxidant, and chain reaction
GHS: person with hazard inside
health hazard: cancer causing agent or substance with respiratory/reproductive/organ toxicity that causes damage over time (chronic/long term health hazard) CRYSTAL VIOLET
Meniscus
is the curvature of the liquid surface in a narrow container. concave: downward curve at the bottom convex: upward read from the top of meniscus
Visible Spectroscopy
is the study of the interaction of radiation from the visible part of the electromagnetic spectrum with a chemical species. Quantifying the interaction of visible light with a chemical sample allows for the determination of an unknown solution concentration
GHS: hand and liquid
materials causing skin corrosion/burns or eye damage on contact or that are corrosive to metals amines/ sodium hydroxide/sulfuric acid hydrogen peroxide/bromine oxalic acid hydrochloric acid acetic acid ammonia
What is the sig fig rules for graduated cylinder?
record all the numbers associated with the markings and then the last number to right is an estimation where the top (or bottom) of the meniscus falls between the last two markings. usually 3 significant figures
accuracy
refers to the closeness of a measurement to the true value. If a true value is known percent error (also known as percent accuracy) can be used to quantify the closeness to the true value.
precision
refers to the reproducibility of a measurement (or measurements).
What is in a spill kit? whats missing?
safety goggles, dust pan and broom, gloves, absorbent pads, citric acid (to neutralize bases), sodium bicarbonate (to neutralize acids), vermiculite (absorbs corrosive liquids), trash bags > A lab coat or change of clothes that might be needed if the chemical spilled on one's clothing.
Standard solution/stock
solutions of a known concentration and are formed by dissolving desired amount of solute into a volumetric flask stock--> if solutions are made of lessened concentration
What are 3 main items to consider for risk of spill?
volume of spill hazards related to the material extreme hazards (ex: electrical equipment, location, etc.)
When diluting an acid, which do you add first: water or acid?Which one do you ADD to the other?
water then acid
