化工群英文示例 沙鹿高工 簡佩琳

Analytical Chemistry Teaching Plan Unit Name Infrared Spectrometer   Time 150 minutes Textbook Analytical Chemistry II Design concept 1. Understanding the function of the infrared spectrometer. 2. In addition to the textbook CD-ROM, we also use the Internet to find out more relevant materials with more pictures and rich colors to help students learn efficiently. Student learning conditions 1. Students have studied general chemistry (chemical bonds, organic chemistry), analytical chemistry (Light fundamental principles of analysis, visible light and ultraviolet spectrometers). 2. Students have been operating the photometer. 3. The students are in the chemical engineering department .

2. Projector, computer, network resources Teaching Resources   1. Textbook Analytical Chemistry II 2. Projector, computer, network resources Teaching Objectives First: Cognitive domain 1. Students can understand the principle and structure of infrared light spectrometer 2. Students can recognize different kinds of infrared spectrometers. 3. Students can learn to distinguish the structure of the compound from the infrared spectrum. Second: Affect domain 1. Students can enjoy most of the classroom activities. 2. Develop the interests of the students in theproces of operating instruments.

Teaching Activities A. Preparations   Matters need to attention or think about Teaching Evaluation A. Preparations 1. Collecting and arranging the teaching materials of infrared spectrometer. 2. Computer and Projector. .

B. Development activities Teaching Activities   Matters need to attention or think about Teaching Evaluation B. Development activities The first section: The principle of infrared absorption spectroscopy 1. The principle of infrared radiation absorption spectrum .The difference between UV and visible light spectrometer. 2. Ask students if they can give examples of polar covalent bonds. 3. Explain the direction of the electric field and the dipole moment . 4. Explain what are infrared light active vibration and infrared light non-active vibration. 5. Introduce how the two physical quantities to affect the frequency of bond stretching vibration. 6. Ask students to show the relationship between the frequency and bonding energy of Table 7-4. 7. Introduce the IR spectrum and let students to observe the curve. 8. Tell the differences in absorption peaks of gases, liquids, and solids 9. Introduce the wave number of three infrared spectrum regions . 1.Pay attention to the ways the students ask. 2.Note whether the students look at the slides or not. . 1.Students can express their opinions fluently.

C. Comprehensive activities 1. Ask students to write exercises. Teaching Activities   Matters need to attention or think about Teaching Evaluation C. Comprehensive activities 1. Ask students to write exercises. 2. Ask students to write quizzes. 3. Ask students to write out answers . 4. Post answers and explain. 5. Play related video. 3.Pay attention to what the students wrote. 3.Students can solve the problems and know how to explain the answers.

The functions of IR spectroscopy (紅外線光譜) IR spectroscopy can be used to distinguish (區分) one compound(化合物) from another.

Absorption of IR energy by organic compounds (有機化合物) will occur in a manner characteristic of the types of bonds and atoms in the functional groups(官能基) present in the compound. Thus, infrared spectrum gives structural information (結構資訊) about function groups in a molecule.

Organic compounds Frequency of the function groups (官能基振動頻率) Alcohol(醇) -Broad OH absorption @ 3300 -3000 cm-1 -C-O absorption @ 1300 -1000 cm-1 Carboxylic acids(酸) -Broad OH Absorption @ 3300-2500 cm-1 Amide(胺) -NH Absorption @ 3500 cm-1(1 or 2 peaks) Easter(醚) C-O Absorption @ 1300-1000 cm-1

Infrared absorption spectroscopy is the covalent bond (共價鍵) of molecules that produces vibrational absorption (振動吸收) spectra.

The Vibrations of the molecule ( Stretching and Bending ) A. Stretching Vibration(伸縮振動) : Changes in bond length(鍵長)

B. Bending Vibration(彎曲振動) :Changes in bond angle(鍵角) In-Plane(平面)

Out-of-plane(非平面) Due to the six vibrations ,the molecule get vibrated(振動) and absorbed (吸收) by IR.

Polar Covalent Bond Have a dipole moment(偶極矩) : when the atoms forming a covalent bond are not the same , the electron density(電子密度) of the two atoms is not the same. Have a positive (正)charge and a negative(負) charge at both ends of the bond.

larger electronegativity(電負度) ---higher electron density --- a slight amount of negative charge ( δ− ) lower electronegativity(電負度) ---smaller electron density --- a slight amount of positive electricity ( δ+ )

The direction of the electric field(電場) is the same as the dipole moment, the bond will be compressed (壓縮) and the dipole moment will be reduced because of the homogeneity of the charge.

The direction of the electric field is opposite to the dipole moment, the bond will be elongated(拉長) due to the attraction of the charge. The dipole moment increases.

Conclusions: The interaction of bond elongation or compression is affected by electromagnetic waves (電磁波). Only polar covalent bonds (極性共價鍵) can interact with infrared light.

Only vibrations with dipole moment changes will generate electromagnetic oscillations(電 磁振盪), and they will resonate with infrared light to absorb the energy of infrared light, which is called infrared activity(紅外線活性). Molecular vibration can not produce infrared light absorption, said non-infrared activity(非 紅外線活性).

According to the Hooke's law, the frequency of stretching vibration between two atoms is related to : The mass of two atoms(原子質量) : The greater the mass of an atom, the slower the vibration

Bonding strength (強度)between two atoms: the greater the bonding strength ,the faster the vibration

quantitative analysis molecule with haevy atoms Region Transition Wavelength ( μm ) Wavenumber (cm-1) Near IR (NIR) overtones quantitative analysis (定量分析) 0.75-2.5 13,300-4,000 Mid IR Fundamental Vibs , rots(轉動) organic analysis 2.5-25 4000-400 Far IR Skeletal(骨架), rots molecule with haevy atoms 25-1000 400-10

1.Which compound’s absorption peak can not be found in the IR spectrum? (A) CO2 (B)O2 (C)H2O (D)CH3COOH Answer: (B)

down which vibration is out of the plane? 2.Please name these vibrations and write down which vibration is out of the plane? 1. 2. Answer: 1.Rocking 2.Twisting

Answer: triple bond> double bond>single bond 3.Please order these three bonds by the frequency of vibration: Answer: triple bond> double bond>single bond

4.Which region of IR is used for the organic analysis? Answer: Mid IR

How to prepare the sample for the IR spectrometer? https://youtu.be/uuAjA9UbA7Y