University:
Boston University
Course:
CAS CH 214 | Organic Chemistry with Qualitative Analysis
Academic year:

2024
Views:

44

Pages:

3
Author:

laj1a2s2z03ah

TP The periodic table indicates that “C” has a mass of 12.011. Which of the following statements is true? 14% 14% 14% 14% 14% 14% 14% 1. 2. 3. 4. 5. 6. 7. All carbon atoms have mass 12.011 g All carbon atoms have mass 12.011 No carbon atoms have mass 12.011 g No carbon atoms have mass 12.011 1 and 2 are correct 3 and 4 are correct None of the above 1 u is defined to be exactly 1/12 mass of 1 atom of 12C Exactly 12 g of 12C contains Therefore, the mass of one 12 g/NA 1.99265 6.02214 A 12C 1023 atoms atom is … 10‒23 g … 1/12 x 1.99265 10‒23 g For today … • Continue: Isotopes  atomic weight • Chemist’s dozen: The mole To memorize: Tables 3.2 and 3.4; Figures 3.7 and 3.8 see Handouts tab Quiz Which of the following is the correct mass of a 12C atom? Atomic mass unit u And so, 1 u Lecture 1.66054 10‒24 g 13% 13% 13% 13% 13% 13% 13% 13% 1. 2. 3. 4. 5. 6. 7. 8. 12 12 g 12 u 12 g/mol 12.011 12.011 g 12.011 u 12.011 g/mol 1 Mass spectrometer “weighs” atoms Average mass of CH101 students? 75 students weigh 100 lbs 100 students weigh 150 lbs 50 students weigh 200 lbs Sketch the “mass spectrum” of the class, using just counts for the vertical axis Strip away an electron, accelerate positive ions, and then deflect them in a magnetic field. Less deflection, heavier mass Neon has three “isotopes”: 20Ne, 21Ne, and 22Ne Relative peak heights  isotopic abundance TP For our hypothetical class, 75 students weigh 100 lbs, 100 students weigh 150 lbs, 50 students weigh 200 lbs. Based on your “mass spectrum” sketch, roughly guesstimate , what will the average be? 0% 0% 0% 0% 1. 2. 3. 4. Less than 100 Between 100 and 150 Between 150 and 200 Greater than 200 Average mass of CH101 students? 75 students weigh 100 lbs 100 students weigh 150 lbs 50 students weigh 200 lbs What is the expression for the fraction of students with mass 150 lbs, ? … 2 Average mass of CH101 students? Average mass of CH101 students? 75 students weigh 100 lbs In terms of the fractions to the exact average. 100 students weigh 150 lbs total mass 50 students weigh 200 lbs In terms of the fractions to the exact average. , , and , write the expression that evaluates 75 average mass , 100 lbs , and 100 , write the expression that evaluates 150 lbs total mass / students 50 / 75 200 lbs 100 50 total mass / 225 75/225 100 lbs 100 lbs 100/225 150 lbs 150 lbs 50/225 200 lbs 200 lbs TP For our hypothetical class, average weight of a CH101 student is 144 lbs. Which of the following statements is true for this class? 0% 1. The weight of each student is 144 lbs 0% 2. No student weighs 144 lbs 0% 3. Neither of the statements is true. 3