lab reports- half life
Name:Date:

Graded Assignment

Lab Report

Answer each question, using complete sentences. When you have finished, submit this assignment to your teacher by the due date for full credit.

(10 points)

Score
  1. You may use Table 1: Analysis of Decay of your laboratory guide to help you with this question. A very old tree limb contains an amount of carbon-14 that is approximately 1/8 of the current atmospheric 14C levels.. Calculate your answers to the following and be sure to show all steps of your calculations.
  • Approximately how long ago was the tree cut down?
  • If there were 1,500,000 carbon-14 atoms to begin with, how many atoms would remain?

Answer:

­­

(5 points)

Score
  1. Consider that Carbon-14 has a half-life of 5,750 years and the following timeline. Why is carbon-14 used to evaluate the age of ancient human remains, but is not used to date dinosaur bones?

word image 116

http://www.irregularwebcomic.net/2601.html

Answer:

(5 points)

Score
  1. The half-life of a sample of potassium-40 (40K) is approximately 1.3 billion years. Potassium -40 decays into argon-40 (40Ar). Some rocks containing potassium -40 have been here since the earth formed and have been accumulating argon-40 to the present day. When rocks are super-heated by volcanic action, all the 40Ar escapes the rock. Create your own imaginative scenario and discuss the value of potassium-argon dating to geologists. Base your answer on your own understanding of half-life.

Answer:

Your Score___ of 20
Name:Date:

Graded Assignment

Lab Report

Answer the questions below. When you have finished, submit this assignment to your teacher by the due date for full credit.

(7 points)

Score
  1. Define an isomer? From your work in the lab and the lab manual, how many isomers does heptane have? When considering isomers, what structural differences make molecules isomers. Sketch the two isomers of heptane you made in the lab using your models of methane and hexane. You may incorporate a picture of the molecules in the space.

Answer:

(6 points)

Score
  1. Please look at ‘Table 1: Boiling Points of Alkanes’ from lab 13. Butane is listed as having two isomers but heptane has nine isomers. Clearly discuss why increasing the number of carbon atoms in the alkane increases the number of possible isomers.

Answer:

(7 points)

Score
  1. Please look at ‘Table 1: Boiling Points of Alkanes’ from lab 13. Previously we have discussed intermolecular forces, which control the physical properties like melting point and boiling point.
    1. Use this prior chemistry knowledge and discuss why we see an increase in boiling point with larger alkane molecules
    2. The table provides the boiling point for the straight chain alkane. Isomers of an alkane do not all have the same boiling point. Again, rely on your previous knowledge of intermolecular forces to thoroughly discuss why isomers have different boiling points.

Answer:

Your Score___ of 20

Graded Assignment

Lab Report

Answer the questions below. When you have finished, submit this assignment to your teacher by the due date for full credit.

(7 points)

Score
  1. Define an isomer? From your work in the lab and the lab manual, how many isomers does heptane have? When considering isomers, what structural differences make molecules isomers. Sketch the two isomers of heptane you made in the lab using your models of methane and hexane. You may incorporate a picture of the molecules in the space.

Answer:

(6 points)

Score
  1. Please look at ‘Table 1: Boiling Points of Alkanes’ from lab 13. Butane is listed as having two isomers but heptane has nine isomers. Clearly discuss why increasing the number of carbon atoms in the alkane increases the number of possible isomers.

Answer:

(7 points)

Score
  1. Please look at ‘Table 1: Boiling Points of Alkanes’ from lab 13. Previously we have discussed intermolecular forces, which control the physical properties like melting point and boiling point.
    1. Use this prior chemistry knowledge and discuss why we see an increase in boiling point with larger alkane molecules
    2. The table provides the boiling point for the straight chain alkane. Isomers of an alkane do not all have the same boiling point. Again, rely on your previous knowledge of intermolecular forces to thoroughly discuss why isomers have different boiling points.

Answer:

Your Score___ of 20
Order a unique copy of this paper
(550 words)

Approximate price: $22