Chemistry Lab Safety Rules RP 273

• Chemistry Laboratory RP 273 Lab Manual was compiled by Ami Johannes in November 2021

Laboratory Safety Rules

• Lab safety rules are based on common sense, emphasizing awareness of surroundings
• Wear eye protection (goggles or approved glasses) at all times, avoiding contact lenses
• Wear closed-toe shoes to protect against dropped glassware
• Confine long hair and loose clothing; use a lab coat
• Use correct apparel when handling dangerous chemicals like a lab coat, apron, gloves and face shield
• Perform only authorized experiments with specified chemicals and quantities
• No eating or drinking is allowed in the lab
• Never use mouth-pipetting, and always instead use a pipette bulb
• Avoid touching chemicals, as many are absorbed through the skin
• Wash off skin chemicals with ample water
• Dispose of chemicals in designated collection bottles, not the sink, after consulting the TA
• Small quantities of innocuous reagents may be flushed down the sink with running water after consulting the TA
• Learn chemical hazards from material safety data sheets
• Never work alone; ensure at least one other person is present, with the instructor or TA available

Emergency Procedures

• Read posted emergency directions and in emergencies, notify occupants, evacuate, and call 911
• Immediately report fires or accidents to the instructor or TA
• Do not run if clothing catches fire; use the fire blanket or emergency shower to extinguish flames
• Know where fire extinguishers and eyewash stations are located
• Flush eyes with water for 15 minutes if exposed to chemicals and seek immediate medical attention
• Wash chemical spills on the body or clothing with large amounts of water, using the emergency shower, and remove affected clothing
• Know the location of the emergency shower and eyewash sink
• Report all injuries to the instructor or TA

Lab Report Guidelines

• Lab reports should be a typewritten, lengthier version of the lab notebook in paragraph form without an outline
• A lab report should have a title page (5 points) with the experiment title, experiment names, and experiment dates
• An introduction or background section (20 points) explains the experiment's purpose, analysis, methods, theory, and pertinent chemical equations
• The procedure section (15 points) summarizes the experiment's steps in past tense, including instrumental parameters and relevant references
• The data section (30 points) presents tabulated data with titles/numbers and includes appropriate figures with titles, numbers, and sample calculations
• The results and discussions section (25 points) discusses results, trends, findings, objectives, error sources, and improvement suggestions
• A references section (5 points) lists author, title, edition, city, publisher, and publication year
• Write-ups must use the past progressive tense and avoid pronouns like "I" or "We"; for example, "A 250 mL solution of 0.01 M NaCl was prepared"

Experiment 1: Pipette Calibration

• The experiment determines the accuracy of a pipette
• Uncertainty exists in chemistry lab measurements, so it should be minimized for precision and accuracy
• Calibrating ensures pipette accuracy
• Pipette accuracy is determined using D=M/V
• Determine pipettes volume using the equation, distilled water mass, and waters density
• An analytical scale and list of waters densities at various temperatures determines volume to four digits
• Repeat measurement indicates precision.

Pipette Calibration Materials

• Pipette
• Pipette bulb
• Analytical balance
• Kim wipes (tissue paper)
• Vial, small Beaker, or flask
• Unknown liquid

Pipette Calibration Safety

• Wear safety goggles and an apron in the lab
• Never use mouth suction for a pipette: only a pipette bulb
• Treat balances carefully as they are very delicate

Pipette Calibration Procedures:

• Accurately weigh a small, clean flask/beaker; record that mass
• Fill the pipette carefully, adjust the water to the line, and transfer its contents
• Weigh the container with water, and record the value
• Repeat the procedure four more times
• Measure water temperature, and find water density in a table and record the density
• Calculate the pipette volume using the water mass and density and then calculate the average volume and SD of measurements
• Calculate % relative error in the 10 mL pipette specification
• Determine determination precision for pipette volume and express as a relative SD in parts per thousand

Experiment 2: Acid-Base Titration

• The purpose of this lab is to experimentally determine the concentration of an unknown base solution
• The experiment is in four parts:
• Preparation of NaOH solution of unknown base and it's standardization and titration for an acids exact concentration
• With the acid solution from Part 3, experimentally determine the unknown base concentration

Experiment 3: Water Hardness

• Hard water occurs due to dissolved metal ions (minerals like Ca2+, Mg2+, Fe3+, SO42, HCO3) in groundwater
• Water hardness is measured with CaCO3.
• Measuring water hardness determines water quality for home and industrial use
• Originally, water hardness measured the capacity of water to precipitate soap
• Hard water is not a health hazard, but contributes calcium and magnesium to human diet
• Hard water causes soap scum as calcium ions bind to soap
• Heated water precipitates CaCO3 causing damage and malfunction
• Water softeners remove hardness, replacing Ca2+ with Na+ which makes it too salty for drinking

Types of Water Hardness:

• Temporary hardness is when bicarbonate ion, HCO3 is present in the water, removed by boiling: HCO3 <-> H2O + CO2(g)
• Permanent hardness happens when ions Ca2+, Mg2+, Fe3+, and SO42 are in water and cannot be eliminated by boiling

Water Hardness Degrees:

• Soft Water has CaCO3 concentration is 0 - 75 mg/L
• Medium hard Water has CaCO3 concentration is 70 - 150 mg/L
• Hard Water has CaCO3 concentration is 150 to 300 mg/L
• Very hard Water has CaCO3 concentration > 300 mg/L
• Permanent hardness is found by titrating in a stndard solution using ethylenediamminetetra acetic acid, EDTA
• EDTA is a chelating agent used to capture metal ions, softening the water by binding tightly to the metal ions
• EDTA is a versatile chelating agent, which molecules can form multiple bonds to a single metal ion
• Chelating agents are multi-dentate ligands; ligands are substances that bind metal ions
• Multidentate ligands are many clawed, and hold firmly to metal ions for stable complex

EDTA Uses

• EDTA forms complexes with calcium and magnesium ions, and is used in soaps and detergents
• EDTA is used for hard water, to remove ions from the enzymes that spoil food and to promote the color retention foods
• The lab determines total permanent hardness
• EDTA binds all metal ions (not just Ca2+), resulting in a 1% experimental error

EDTA Endpoint Color Change:

• Eriochrome Black T indicator is used in the titration
• The chelated or acidified form is PINK RED while the non-chelated basic form is BLUE

Experiment 4: Gravimetric Analysis

• Gravimetric analysis isolates a desired constituent in pure/combined form, weighs the isolated constituent, and then the percentage of the constituents is calculated,
• Precipitation affects inorganic/organic precipitating agents

Inorganic Precipitation agents

• Silver nitrate is an inorganic precipitation agent, precipitates halide ions like chloride
• Barium chloride precipitates sulfate ion.
• Potassium, rubidium, cesium ions are precipitations with sodium tetraphenylborate
• The product is a salt since it reactions occur between ion and anions, bonding is electrovalent
• Organic reagents contain carboxyl and hydroxyl groups, ionize into anions, and combine with cations to create insoluble salts (bonding is electrovalent here)
• Silver ions undertake a reaction with chloride
• Silver chloride relatively insoluable compound, solubility product Ksp = [Ag+] [Cl]) of 1.8 10-10.

Experiment 5: pH And Buffer Solutions

• Acids donate protons (hydrogen ions), while bases accept protons based on the Bronsted-Lowry theory
• Acids donate protons while bases accept them
• Strong acids/bases and weak acids/bases have varied strengths

Experiment 6: Enthalpy of Solution (ΔHs)

• One mole of a substance is dissolved in water and the temperature change is recorded, but no more heat is added

Experiment 7: Reaction Of Hydrocarbons

• Hydrocarbons are classified in a few types that differ based off sturcture like:
• Alkanes have single bonds (saturated)
• Alkenes and Alkynes have double/triple bonds (unsaturated)
• Aromatic hydrocarbons are cyclic (benzene-related)
• This experiment explores fundamental reactions of saturated, unsaturated, and aromatic hydrocarbons (reacting differently with reagents)

Experiment 8: Identification Of Alcohols And Phenols

• Specific atoms determine an organic m molecule's properties
• These groups are called functional groups, like the hydroxyl in alcohol
• Alcohols are used frequently in solvents, drugs and disinfectants

9: Synthesis of Esters

• A class of organic compounds prepared from the reaction of a classification reaction of an organic acid with alcohol with a strong acid (H2SO4)
• They impart aromas associated with the different fruits used in cosmetics and perumes
• Esters posses important psychological effets like acetylsalicyclic (aspirin) acts as an analgesic and an antipyretic

Liniments:

• Liniments contain methyl salicylate, which is prepared from reacting methyl alcohol with thesalicylic acid group.