Why should you never distill a flask to dryness?

It is a major safety hazard; high-boiling residues can become unstable or explode when heated without the bulk liquid present

What does a "misty ring" in the distillation or reflux column indicate?

It is the condensation point where vapors are turning back into liquid

In GC, what determines how much sample is actually analyzed?

Even though the vial contains 1.5 mL, the auto-sampler only injects 1 µL into the instrument

How does altitude affect Boiling Point?

Higher elevations have lower atmospheric pressure, which leads to lower boiling points

Where do sp³ C-H (alkane) peaks appear in an IR spectrum?

Strong to medium peaks between 2850 and 2960 cm⁻¹

Where do Aromatic C=C peaks appear?

Medium intensity peaks between 1450 and 1600 cm⁻¹

Why do we use KBr (Potassium Bromide) plates for IR?

KBr does not absorb infrared light in the region of interest, allowing the spectrum to show only the sample's absorptions

How should you handle IR salt plates?

Exclusively by the edges; oily residue from fingers can interfere with the spectrum

How can you tell if a reaction successfully removed a hydroxyl (-OH) group using IR?

The large broad peak between 3200–3600 cm⁻¹ will be absent in the product's spectrum

How should the Experimental Procedure be written in your lab notebook?

It should be a record of exactly what you did during the lab, including all physical observations and actual data (masses, volumes), not just a copy of the manual

What is the proper "voice" for a formal lab report procedure?

Past tense, third person, passive voice (e.g., “The solution was filtered” rather than “I filtered the solution”)

What should be included in the "Results and Discussion" section of a report?

Data tables, an explanation of the results, identification of the product, and a discussion of purity based on boiling point or melting point ranges

What is the purpose of an Abstract in a lab report?

A short summary covering the entire experiment, including the goal, the method, and the final results (such as yield and identity)

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Chem Lab Exam 4

Question	Answer
Why should you never distill a flask to dryness?	It is a major safety hazard; high-boiling residues can become unstable or explode when heated without the bulk liquid present
What does a "misty ring" in the distillation or reflux column indicate?	It is the condensation point where vapors are turning back into liquid
In GC, what determines how much sample is actually analyzed?	Even though the vial contains 1.5 mL, the auto-sampler only injects 1 µL into the instrument
How does altitude affect Boiling Point?	Higher elevations have lower atmospheric pressure, which leads to lower boiling points
Where do sp³ C-H (alkane) peaks appear in an IR spectrum?	Strong to medium peaks between 2850 and 2960 cm⁻¹
Where do Aromatic C=C peaks appear?	Medium intensity peaks between 1450 and 1600 cm⁻¹
Why do we use KBr (Potassium Bromide) plates for IR?	KBr does not absorb infrared light in the region of interest, allowing the spectrum to show only the sample's absorptions
How should you handle IR salt plates?	Exclusively by the edges; oily residue from fingers can interfere with the spectrum
How can you tell if a reaction successfully removed a hydroxyl (-OH) group using IR?	The large broad peak between 3200–3600 cm⁻¹ will be absent in the product's spectrum
How should the Experimental Procedure be written in your lab notebook?	It should be a record of exactly what you did during the lab, including all physical observations and actual data (masses, volumes), not just a copy of the manual
What is the proper "voice" for a formal lab report procedure?	Past tense, third person, passive voice (e.g., “The solution was filtered” rather than “I filtered the solution”)
What should be included in the "Results and Discussion" section of a report?	Data tables, an explanation of the results, identification of the product, and a discussion of purity based on boiling point or melting point ranges
What is the purpose of an Abstract in a lab report?	A short summary covering the entire experiment, including the goal, the method, and the final results (such as yield and identity)

Created by: bbrdd

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