CHEM 1214 Lecture Notes - Lecture 3: Fluoropolymer, Stoichiometry, Proton-Exchange Membrane Fuel Cell

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pearwallaby931

15 Sep 2016

School

Northeastern University

Department

Chemistry & Chemical Biology

Course

CHEM 1214

Professor

Lykourinou Vasiliki

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Document Summary

Fuel cells: a few cell is a type of battery that utilizes a redox reaction between hydrogen and oxygen to produce water and electrical energy, fuel cells, like other batteries, utilize a redox reaction to generate electrical energy. However, unlike other batteries, fuel cells must be continuously supplied with oxidant (oxygen gas) and reductant (hydrogen gas in order to operate) Combustion reactions are redox reactions, and most common fuel cells involve the combustion of hydrogen and oxygen gas to form water vapor: 2h2 (g) + o2 (g) 2h2o (g) e cell = 1. 23 v: in fuel cells, hydrogen gas become oxidized at the anode and the oxygen gas is reduced at the cathode in two separate half reactions: In breaking the h-h bonds in the oxidation half reaction, hydrogen ions (h+) are produced at the anode. Anode reaction: 2h2 (g) 4h+ + 4e- (oxidation) The hydrogen ions produced migrate through the electrolyte through the electrolyte to the cathode.

Related Questions

1. (1 point) What are transferred in an oxidation-reduction reaction? *

â¢ atoms

â¢ electrons

â¢ ions

â¢ protons

2. (1 point) In the reaction of beryllium with fluorine, which atom is oxidized? *

â¢ fluorine

â¢ beryllium

â¢ neither of them

â¢ both of them

3. (1 point) Ag - - > Ag ^+ +1 e^- This equation represents the type of reaction called _____. *

â¢ hydrolysis

â¢ oxidation

â¢ redox

â¢ reduction

4. (1 point) What is the reducing agent in the following reaction? 2K + S - - > K2S *

â¢ K

â¢ S

â¢ K2S

â¢ None of the above

5. (1 point) The oxidation number of oxygen when it is in a compound other than a peroxide is ____. *

â¢ -2

â¢ -1

â¢ 0

â¢ +2

6. (1 point) What is the oxidation number for each atom in NH4F? *

â¢ N=+3, H=-4, F=+1

â¢ N=-3, H=+1, F=-1

â¢ N=+3, H+1, F=-1

â¢ N=-3, H=-1, F=+1

7. (1 point) Which atom has a change in oxidation number of +4 in the following redox reaction?K2Cr2O7 + H2O + S - - > KOH + Cr2O3 + SO2 *

â¢ K

â¢ Cr

â¢ O

â¢ S

Metal activity series for question 8

8. (1 point) Of the following metals, which ions are most easily reduced? Use the above table to answer the question. *

â¢ magnesium

â¢ lead

â¢ copper

â¢ sodium

9. (1 point) In a zinc-copper cell, Zn(s) | Zn^+2(1M) || Cu^+2(1M) | Cu(s), which electrode is positive? *

â¢ Cu^+2

â¢ Cu(s)

â¢ Zn(s)

â¢ Zn^+2

10. (1 point) How must a redox reaction that is to be used as a source of electrical energy be set up? *

â¢ One half reaction must involve two metals.

â¢ Two half reactions must use a metal wire electrodes.

â¢ One half reactions must involve more than one electron.

â¢ Two half reactions must be physically separated.

11. (1 point) In a voltaic cell at which electrode does reduction occur? *

â¢ anode only

â¢ cathode only

â¢ both anode and cathode

â¢ Either anode or cathode , depending on the metal

12. (1 point) What assures that there is no charge build up in a voltaic cell as oxidation and reduction occur? *

â¢ one of the half cells

â¢ the electrolyte solutions

â¢ the moving electrons

â¢ the salt bridge

13. (1 point) In the most common dry cell what material is the electrode that is the center rod made of? *

â¢ copper

â¢ graphite

â¢ lead

â¢ zinc

14. (1 point) To charge a lead storage battery you must ________. *

â¢ apply a direct current to it.

â¢ hold a magnet close to it.

â¢ Use alternating current through it.

â¢ increase the oxygen in it.

15. (1 point) In a hydrogen- oxygen fuel cell ______________. *

â¢ hydrogen diffuses through the cathode.

â¢ hydrogen and oxygen are mixed before entering the anode.

â¢ oxygen diffuses through the anode.

â¢ oxygen diffuses through the cathode.

16. (1 point) When electrical energy is used to cause a chemical reaction we call this process _____. *

â¢ electronation

â¢ electrolysis

â¢ hydration

â¢ reduction

17. (1 point) Which of the following is true about an electrolytic cell? *

â¢ It changes chemical energy into electrical energy.

â¢ It is the type of cell used in electrocution

â¢ It uses an electric current to make a nonspontaneous reaction go.

â¢ All of the above

18. (1 point) The products formed in the net reaction of the electrolysis of water are ____. *

â¢ aqueous hydrogen ion and hydroxyl ion

â¢ hydrogen gas and oxygen gas

â¢ hydrogen gas and liquid oxygen

â¢ water vapor

19. (1 point) What occurs in electroplating? *

â¢ decomposition of an ionic compound

â¢ decomposition of a salt layer

â¢ deposition of a metal layer on a material

â¢ deposition of a salt layer on a metal

Open response Questions : Answer questions 20 through 22 in complete sentences

20. ( 5 points) Write the equation for the reaction of calcium and oxygen ( 1 point). Write the oxidation numbers for both the reactants and the products ( 2 points) What is the reducing agent and why? ( 2 points)

21. ( 5 points) Tell how a voltaic cell works. Be sure to mention the various parts of the voltaic cell and what they have to do with how it works.

22. (4 points) What are the signs given to the electrodes in both the voltaic and electrolytic cells? What reaction (oxidation or reduction) is occurring at each?

peargnat685

Part A A fuel cell differs from a battery because the current is being generated from a reduction-oxidation (redox) reaction in which the reactant is consumed. A classic example of a fuel cell is the phosphoric acid fuel cell (PAFC), which have been used in stationary power generators, buses, and even submarines. Fuel cells require an electrolyte (similar to batteries) to carry electrically charged species between the electrodes, and a PAFC utilizes phosphoric acid (H3PO4) as its electrolyte. Phosphoric acid has three acidic protons that can dissociate in water, as highlighted in red here: H3PO4. However, it is considered a weak acid because some of the acid will remain in molecular form when dissolved in water. Write the complete ionic equation that depicts the dissociation of the first proton for the weak acid phosphoric acid (H3PO4). Make certain you include all charges for any ions produced. Express you answer as a chemical equation including phases. Titrations as analytical neutralization reactions Neutralization reactions can occur between any combination of weak/strong acids and bases. When we want to determine the concentration of a base in solution, we can apply the concept of neutralization by reacting the base with a known amount of an acid in the presence of an indicator (a compound that changes color depending on the pH). This method of determining the concentration of a base is called acid-base titration, and it can also be used to determine the concentration of an acid by titrating it with a known amount of base. A common acid to use for titrations is potassium hydrogen phthalate (written as KHP or KHPh; do not confuse the P for phosphorus). The reason KHP is common is because it is solid at room temperature, and we can accurately mass the amount that is added to solution. As a soluble salt, KHP completely dissociates to form a potassium ion (K+) and an acidic hydrogen phthalate ion (HPâ), which is a weak acid that has only one acidic hydrogen. This ionization is depicted below. KHP(s) â K+(aq)+HPâ(aq) Although ionization (the formation of ions) occurs as a result of acid dissociation for most weak acids, KHP ionizes before acid dissociation occurs. In other words, HPâ is a weak acid ion. Part C If you wanted to determine how much KOH (potassium hydroxide; a strong base) was dissolved in water, you could titrate it with a known amount of KHP (potassium hydrogen phthalate; a weak acid) until a color change indicates that the base is completely neutralized. The molecular equation below depicts this neutralization reaction. KHP(aq)+KOH(aq)âK2P(aq)+H2O(l) Write the net ionic equation that depicts the neutralization of the base by potassium hydrogen phthalate. Instead of using the entire chemical formula of phthalate, use HPâ to represent the acidic hydrogen phthalate ion and P2â to represent the phthalate ion. Express your answer as a net ionic equation including phases.

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

c. CH₃-O-CH₃

d. CH₃OH

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

a.-C=O b. âOH c. âO- 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 âCOOH 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

CHEM 1214 Lecture Notes - Lecture 3: Fluoropolymer, Stoichiometry, Proton-Exchange Membrane Fuel Cell

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