Log in
HomeStudy Guides420,000US230,000

CHM 124 Study Guide - Midterm Guide: Mechanistic Organic Photochemistry, Chloromethane, Photocatalysis

40 views3 pages
amaranthtoad188
7 Dec 2017
School
URI
Department
Chemistry
Course
CHM 124
Professor
Shahla Yekta

For unlimited access to Study Guides, a Grade+ subscription is required.

Document Summary

These are reactions in which one atom in a molecule is replaced by another atom or group of atoms. Free radical substitution for a" level purposes involves breaking a carbon-hydrogen bond in alkanes such as methane ethane ch3ch3 propane. A new bond is then formed to something else. It also happens in alkyl groups like methyl, ethyl (and so on) wherever these appear in more complicated molecules. methyl ch3 ethyl ch3ch2. For example, ethanoic acid is ch3cooh and contains a methyl group. The carbon-hydrogen bonds in the methyl group behave just like those in methane, and can be broken and replaced by something else in the same way. A simple example of substitution is the reaction between methane and chlorine in the presence of uv light (or sunlight). Notice that one of the hydrogen atoms in the methane has been replaced by a chlorine atom. Free radicals are atoms or groups of atoms which have a single unpaired electron.

Get access

Grade+
$40 USD/m
Billed monthly
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
10 Verified Answers

Related Documents

CHM 124
Final Exam
Study Guide
CHM 124 Study Guide - Midterm Guide: Methyl Group, Benzene, Chain Termination
amaranthtoad188
CHM 124 Lecture Notes - Lecture 3: Sigma Bond, Ethylene
amaranthtoad188
CHM 124 Lecture Notes - Lecture 12: Styrene, Nitration, Ethylbenzene
amaranthtoad188

Related Questions

The rates of many atmospheric reactions are accelerated by the absorption of light by one of the reactants. For example, consider the reaction between methane and chlorine to produce methyl chloride and hydrogen chloride:

Reaction 1: CH4(g) + Cl2(g) CH3Cl(g) + HCl(g)

This reaction is very slow in the absence of light. However, Cl2(g) can absorb light to form Cl atoms:

Reaction 2: Cl2(g) + hv 2 Cl(g)

Once the Cl atoms are generated, they can catalyze the reaction of CH4 and Cl2, according to the following proposed mechanism:

Reaction 3: CH4(g) + Cl(g) CH3(g) + HCl(g)
Reaction 4: CH3(g) + Cl2(g) CH3Cl(g) + Cl(g)

The enthalpy changes and activation energies for these two reactions are tabulated as follows:

(a) By using the bond enthalpy for Cl2 (Table 8.4), determine the longest wavelength of light that is energetic enough to cause reaction 2 to occur. In which portion of the electromagnetic spectrum is this light found? (b) By using the data tabulated here, sketch a quantitative energy profile for the catalyzed reaction represented by reactions 3 and 4. (c) By using bond enthalpies, estimate where the reactants, CH4(g) + Cl2(g), should be placed on your diagram in part (b). Use this result to estimate the value of Ea for the reaction CH4(g) + Cl2(g) CH3(g) + HCl(g) + Cl(g). (d) The species Cl(g) and CH3(g) in reactions 3 and 4 are radicals, that is, atoms or molecules with unpaired electrons. Draw a Lewis structure of CH3, and verify that it is a radical. (e) The sequence of reactions 3 and 4 comprises a radical chain mechanism. Why do you think this is called a “chain reaction”? Propose a reaction that will terminate the chain reaction.

Test 1-Multiple Choice: Choose and underline the best answer in each of the following statement/question.

_____1. Which of the following best differentiates an aldehyde from a ketone?

a. In aldehydes, carbon is bonded to a hydroxyl group.

b. In aldehydes, hydrogen is bonded to an oxygen group.

c. In aldehydes, hydrogen is bonded to a carbonyl group.

d. In aldehydes, oxygen is bonded to an oxygen group.

_____2. Which of statement is not true about petroleum and its products?

a. Petroleum is fossil fuel.

b. Petroleum is a mixture of hydrocarbons with sulfur as impurity.

c. There is no harm that comes from the use of petroleum products.

d. Petroleum comes from decomposition of materials of living origin.

_____3. Cooking gas or liquefied petroleum gas(LPG) is a mixture of C3H8 and C4H10. Which are these compounds?

a. pentane and butane b. methane and butane

c. propane and butane d. propane and methane

_____4. Which of the following compounds ionizes in water and, thus conducts electricity poorly?

a. acetic acid b. hydrochloric acid c. distilled water d. sodium hydroxide

_____5. A lead storage cell can function both as an electrolytic cell and as a voltaic cell. When a lead storage battery is being recharged, it converts ________ energy to_____--energy

a. chemical : electrical b. chemical to heat c. electrical to mechanical

_____6. The acid electrolyte in a lead storage battery is

a. HCl b. H2SO4 c. HNO3 d. CH3COOH

____7. The anode and cathode in a dry cell respectively are

a. Zn and C b. C and Zn c. Pb and PbO2 d. PbO2 and Pb

____8. What is the proper name for the compound CH3CH2CH3?

a. ethane b. propane c.butane d. pentane

____9. Which of the following is the simplest hydrocarbon?

a. CH2 b. C2H4 c. CH3 d. CH4

____10. Hydrocarbons such as CH2 =CH2 are said t be

a. ionic b. aromatic c. saturated d. unsaturated

_____11. Which of the following best describes hydrocarbons?

a. flammable ionic compounds that are insoluble in water and are denser than water

b. flammable ionic compounds that are insoluble in water and are denser than water

c. flammable covalent compound that are insoluble in water and are less dense than water

d. flammable covalent compounds that are soluble in water and less dense than water

_____12. Which of the following will result if hexane and water are mixed?

a. an explosion

b. clear solution of hexane dissolved in water

c. a layer of hexane on top of a layer of water

d. a layer of water on top of a layer of hexane

_____13.Which of the following is not a gas?

a. ethene b. octane c. methane d. acetylene

_____14. Which of the following is another name for wood alcohol?

a. methanol b. propanol c. grain alcohol d. rubbing alcohol

_____15. Which of the following alcohols groups are found in beverages?

a. ethyl b. methyl c. denatured d. wood

_____16. Which of the following is the only element present in organic compounds?

a. hydrogen b. oxygen c. carbon d. nitrogen

_____17. Which of the following is chlorofluorocarbon?

a. C3F8 b. CHF3 c. CFCl3 d. CHCl3

_____18.What percent of alcohol is present in vodka which is 90 proof?

a. 9 b. 45 c. 90 d. 180

____20. Which of the following is formed when carbohydrates undergo fermentation process?

a. ethanol b. methanol c. glucose d. formaldehyde

_____21. In ethene, the two carbon atoms are joined by a

a.single bond b. double bond c. triple d. ionic

____22. The IUPAC name of CH3CH2CHCH2CH3 is

│

CH2CH3

a. 3-methylpentane b. 3-ethylpentane c. 2-ehtylpentane d. 2-methylpentane

____23. The IUPAC name of CH3-O-CH3 is

a. methoxymethane b. ethylether c. dimethylether d. dimethyloxide

____24. Which is an alcohol?

a. C6H6

b. CH3-C-CH3

│

O

c. CH3-O-CH3

d. CH3OH

____25. A group which both aldehydes and ketones have in common is

a.-C=O b. –OH c. –O- d. -COOH

___26. The aroma associated with this class of compounds is regarded as pleasant.

a. amides b. esters c. carboxylic acids d. ketones

____27. The IUPAC name of CH3CH2CHO is

a. propanone b. propanol c. propanal d. propionic acid

____28.The –COOH group is called

a. aldehyde group b. hydroxyl group c. carbonyl group d. carboxylic group

____29.The alkyl group of butane is

a. C2H3 b. C3H5 c.C4H7 d. C4H9

____30. The simplest alkene is

a. CH=CH b. CH2=CH3 c. CH2=CH2 d. CH3CH=CH2

Test 2. Answer the following questions completely.(3 points each)

1.Why are alcohols of lower molecular weight more soluble in water than those with higher molecular weights?

2. Which of the following pairs of compounds has

a. higher bolilng point:1-bromopentane or 1-chloropentane _____________________

b. the greater density: heptanes or octane ______________________
c. the higher boiling point :pentyl alcohol or pentylamine ______________________

d. the higher boiling point: hexylamine or dipropylamine ______________________

3. Explain why each of the following names are incorrect.Give the correct IUPAC name.

a. 3-Butanone

b. 1-Butanone

4. What is unique about carbon atom that makes it form numerous compounds?

5. Acetone or propanone is completely soluble in water,but 4-heptanone is completely insoluble.Explain.

Test 3.. Give the name and chemical formula of the functional group of each of the following organic groups. The first one has been done for you.

Organic Group

Functional chemicalfFormula

Functional group name

1.Alkanes

-C-C-

carbon carbon single bond

2.Alkenes

3.Alkynes

4.Alcohols

5. Aldehydes

6. Ketones

7. Thiols

8. Ethers

9.Carboxylic acids

10.Esters

11. Amines

12. Amides