IR Spectroscopy

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Total cards: 24•Content version: v4•Public deck•Updated: 8/1/2026

Card preview (24)

Front (Question)

Larger frequencies (higher energies) are absorbed by…

Back (Answer)

-Bonds with a higher bond order -Bonds between atoms with a larger mass difference

Front (Question)

What is the critical reference value for the N-H/O-H region?

Back (Answer)

3250 cm-1

Front (Question)

How do we differentiate between peaks in the N-H/O-H region?

Back (Answer)

-O-H peaks are typically strong to moderate and broad -N-H peaks are typically moderate to weak and sharp -C-H peaks are very sharp

Front (Question)

What is the critical reference value for the C-H region?

Back (Answer)

3000 cm-1

Front (Question)

How do you differentiate between peaks in the C-H region?

Back (Answer)

-sp3 is to the right of 3000 -sp2 is to the left of 3000 -Aldehyde is 2750 and 2850

Front (Question)

What is the critical reference value for the C triple bond N/C triple bond C region?

Back (Answer)

2250 cm-1

Front (Question)

How do you differentiate between peaks in the C triple bond N/C triple bond C region?

Back (Answer)

-Alkyne peaks are moderate to weak -Nitrile peaks are strong to moderate

Front (Question)

What is the critical reference value for the C=O region?

Back (Answer)

1715 cm-1

Front (Question)

What is the range possible for C=O?

Back (Answer)

1800-1650

#10

Front (Question)

How do you differentiate peaks in the C=O region?

Back (Answer)

C=O peaks are typically strong and slightly broad

#11

Front (Question)

What is the critical reference value for the C=C region?

Back (Answer)

1600 cm-1

#12

Front (Question)

How do you differentiate between peaks in the C=C region?

Back (Answer)

-C=C peaks are typically strong to moderate and sharp -Aromatic C=C is below 1600 cm-1 -Alkene C=C is above 1600 cm-1

#13

Front (Question)

What are critical reference values?

Back (Answer)

Center value of the FG range

#14

Front (Question)

List the approximate zone lines from left to right.

Back (Answer)

3200, 2700, 2000, 1650, 1400

#15

Front (Question)

What is the critical reference value for the C=O FG region?

Back (Answer)

1715 cm-1

#16

Front (Question)

How do you differentiate between peaks in the C=O region?

Back (Answer)

-Aldehyde has present of moderate C-H peak (2x below 3000) -Carboxylic acid has presence of extremely broad O-H peak

#17

Front (Question)

Ester _____ vibrational energy by _____.

Back (Answer)

increases, 30 cm-1

#18

Front (Question)

Amide ______ vibrational frequency by _____.

Back (Answer)

decreases, 30 cm-1

#19

Front (Question)

Acyl halides/anhydrides ______ energy more than ____.

Back (Answer)

increase, 30

#20

Front (Question)

Conjugation decreases vibrational frequency by ______.

Back (Answer)

30 cm-1

#21

Front (Question)

Conjugation on both sides of the carbonyl decreases frequency by _____.

Back (Answer)

60 cm-1

#22

Front (Question)

_______ is strain free and “normal”.

Back (Answer)

cyclohexane

#23

Front (Question)

Ring strain increases vibrational energy by ______.

Back (Answer)

30 cm-1

#24

Front (Question)

More strain = ______.

Back (Answer)

higher energy