0

answers

0

watching

41

views

12 Dec 2019

The CO₂ inventory in todayâs atmosphere is about 780. Gigatons as carbon (1 Gt = 1 x 10¹⁵ grams = 1 Pg).

a.Explain what would happen to the inventory of CO₂ in the atmosphere if the formation of calcite minerals in the ocean were to stop? Assume any other fluxes of ions into or out of the ocean would remain the same.

b.Calculate how long it would take to change todayâs CO₂ inventory of the atmosphere by 33% if the formation of calcite minerals in the ocean were to stop.

0

answers

0

watching

41

views

For unlimited access to Homework Help, a Homework+ subscription is required.

Join us on Discord

Chemistry Study Group

Related textbook solutions

Basic Chemistry

ISBN: 9780134138046

Principles of Chemistry Molecular Approach

ISBN: 9780134112831

Chemistry: Structure and Properties

ISBN: 9780134293936

Principles of Chemistry Molecular Approach

3rd Edition, 2014

ISBN: 9780321971944

Chemistry: A Molecular Approach

ISBN: 9780321809247

Chemistry: A Molecular Approach

ISBN: 9780134874371

Principles of Chemistry: A Molecular Approach

ISBN: 9780134895741

Chemistry: The Central Science

14th Edition, 2017

ISBN: 9780134414232

Related questions

HERE IS HOW THIS IS GOING TO WORK! IF YOU ANSWER THE QUESTIONS IWILL GIVE YOU THE 3K POINTS + MORE AFTER I REPOST IT.

2. The amount of heat involved in the synthesis of 1 mole of acompound from its elements, with all substances in their standardstates at 25*C, is called _________.

3. What is a valid unit for specific heat?

4. Use Hess's Law to find the heat of reaction in the examplebelow.

N2O4 (g) ----> 2NO2 (g)

Given that:

N2O4 (g) ----> N2 (g) + 2O2 (g) (Delta H =-9.7kJ)

2NO2 (g) ----> 2O2(g) + N2(g) ( Delta H= -67.7kJ)

5. Use Hess's Law to find the heat of reaction in the examplebelow. (Example doesn't exist btw.)

6. (Delta H) for the formation of rust (Fe2O3) is -826 kJ/mol. Howmuch energy is involved in the formation of 5 grams ofrust?

7. How many kilocalories of heat are required to raise thetemperature of 50g of aluminum from -5*C to 35*C? (Specific heat ofAluminum = 0.21 cal/g*C)

8.Calculate the (Delta H) for this reaction:

Zn(s) + Cu (2+ ion)(aq) ---> Zn(2+) + Cu(s)

(Delta H) for Cu(2+) = +64.4 kJ/Mol; (Delta H) for Zn(2+) = -152.4kJ/mol

9. The following equation shows the reaction that occurs whennitroglycerine explodes.

4C3H5O9N3 ----> 12CO2 + 6N2 + O2 +10H2O + 1725 Kcal

Is this reaction exothermic , endothermic, a combustion reaction ,or a combination reaction?

10. What does it mean for ammonia, (NH3) to have a (Delta H f) =-46 kJ/mol?

(for example: Define heat of formation. What does a negative heatof formation mean? what do the units of kJ/mol mean?)

11. What is the maximum amount of KCl that can dissolve in 500g ofwater?

(solubility of KCl is 34 g/ 100g of water at 20*C)

12.List the ways(operations) that can help make a substancedissolve faster in a solvent?

13. If a crystal added to an aqueous solution causes many particlesto come out of solution, the original solution was (saturate,unsaturated, supersaturated).

14. What is the number of moles of solute in 165 mL of a 0.82 Msolution?

15. What mass of NaCl is needed to make 350 mL of a 1.00 Msolution?

16. Colligative properties depend upon...

17. If one mole of each of these solutes in added to the sameamount of water, which solution has the highest boiling point?(glucose, aluminum sulfate, magnesium acetate, copper (I)chloride)

18. When an acid reacts with a base, what compounds areformed?

19. If the [H+] in a solution is 1x10^(-13) mol/L, what is the[OH-]?

20. If the [OH-] = 1x10^-6 mol/L, what is the pH of thesolution?

21. For a solution to be considered acidic what must be thehydrogen-ion concentration?

22. Which of the following represents a Bronsted-Lowry conjugateacid-base pair?

a) SO3(2-) and SO2 b) CO3(2-) and CO c) H3O and H2 d) NH4(+) and NH3

23. With solutions of "strong" acids and "strong" bases, the word"strong" refers to ...

24. What are the products of Al(OH)3 + H2CO3?

25.What is the concentration of hydrochloric acid if 5.0 mL of acidis neutralized by 30.0 mL of 2.00M sodium hydroxide.

26. At equilibrium, what is the rate of production of reactantscompared with the rate of production of products?

27. What is the equilibrium constant for the following reaction2SO3 ---> 2SO2 + O2

28. How does an increase in pressure affect the following reaction?2SO3 (g) --> 2SO2(g) +O2(g)

29.What stresses would shift the reaction to the right?

2SO3(g) ==> 2SO2(g) + O2(g)

30. The Keq of a reaction 4.9 x 10^(-7). Are products or reactantsfavored at equilibrium?

31. In which of these systems is the entropy decreasing?

a) air escaping from a tire b) snow melting c) a gas condensing d) salt dissolving inwater

32. If an atom is reduced in a redox reaction, what must occur toanother atom in the system?

33. Identify the oxidizing agent in the following reaction: 2Na + S---> Na2S

34. What are transferred in an oxidation -reductionreaction?

35. Give the oxidation number for each atom in KMnO4.

36. Which atom has a change in oxidation number of +4 in thefollowing reaction?

K2Cr2O7 + H2O + S ----> KOH + Cr2O3 +SO2

37. What is the oxidation number of sulfur in each of the following:

a. SO3 c.SO2(2-)

b. Na2SO4 d. S2O4 (2-)

38.Fe(3+) ----> Fe represents oxidation, reduction, orhydrolysis?

39. When the half reactions Br2+ 2e- -----> 2Br- and Na---->e- + Na(+) are combined the balanced redox equation is_____________________ ( WRITE the BALANCED REDOX eq)

40. To balance the oxygen and hydrogen for a redox reaction thattakes place in basic solution, it is necessary to use whichsubstance?

41. What particle completes this nuclear equation? 55/25 Mn + 2/1 H====> _____ +2 1/0 n

42. The half-life of tungsten-182 (182/74 W) is 1.1x10^(17) years.How long would it take for a 376.2 kg sample to decay until only123.0 grams remain?

43. After 3 days, the quantity of certain radioisotope is reducedfrom 13.6 grams to 1.9 grams. Calculate the half-life of theisotope.

44. What is the name of the compound having the formulaC8H18.

45. What is the name of the following compound:

O

//

CH3---CH2----CH---CH2--C

I \

CH3 OH

46. What is an isomer? Give an isomer of hexane (C6H14) and drawit's structure.

47. What is the name of the hydrocarbons with double covalentbonds?

48. Draw the stucture for 3-methylbutanoic acid.

49. Draw the structure for methylbenzene?

50. What is the name of the following compound:

Br

|

CH3----C-----CH3

|

CH3

47

EXPERIMENT

9

Williamson Ether Synthesis

Reading and Preparation

TaskSource

S

-

115

Safety

Chemwatch

(website)

Background

In todayâs laboratory class you will preparetert

-butyl methyl ether from potassiumtert

-

butoxide

and iodomethane using the Williamson ether synthesis according to Scheme 1. This is classified

as a substitution reaction of an alkyl halide, where iodine

in

iodomethane is replaced by a

tert

-

butoxide group.

Scheme 1

Substitution reactions of alkyl halides can occur by either an SN1 or S

N2 mechanism. In the SN1process, the rate-determining step in the reaction is breaking of the carbon-halogen bond and the

formation of a carbocation intermediate (Scheme 2).Scheme 2Such reactions follow first order kinetics because the rate of the reaction only depends on the

decomposition of one molecule and is therefore only affected by the concentration of the alkylhalide. In the SN2 mechanism,

the rate-determining step is the displacement of the halide by an attacking nucleophile (Scheme 3).

Scheme 3

This reaction follows second order kinetics because the rate depends on the interaction between

two molecules and thus the concentration of both the alkyl halide and thetert

-

butoxide

nucleophile. Nucleophilic substitution reactions are discussed in McMurry,

Chapter 11, pages

C

H

I

H

H

+

C

H

3

C

O

H

3

C

H

3

C

C

H

H

H

C

H

3

C

O

H

3

C

H

3

C

K

+

KI

HOC(CH

3

)

3

C

H

H

H

+

I

C

H

I

H

H

C

H

I

H

H

C

H

3

C

O

H

3

C

H

3

C

C

H

3

C

O

H

3

C

H

3

C

C

H

H

H

+

I

48

372

â

395. You will follow the progress of the reaction between potassium

tert

-

butoxide and

iodomethane in order to determine the mechanism of this reaction. If the reaction follows first

order kinetics, then the reaction occurs by the

S

N

1 mechanism. If the reaction follows second

order kinetics, then the reaction occurs by the S

N

2 mechanism.

The progress of the reaction is monitored by following the change in concentration of the

reactants over time. For this experiment, aliquots of the reaction mixture are withdrawn every

10 minutes for the first hour and every 20 minutes for the second hour

. The aliquots of reaction

mixture are placed in cold water to stop the reaction. The unreacted

tert

-

butoxide ions present

reacts with water to liberate hydroxide ions (Scheme 4).

Scheme 4

(H

3

C)

3

CO

Ì

+ H

2

O

â

(H

3

C)

3

COH + HO

Ì

Hydroxide ion is then t

itrated using standardised sulfuric acid and the concentration of the

tert

-

butoxide ion and iodomethane for each time can be calculated.

Notes

:

1.

The concentration of the

potassium

tert

-

butoxide

stated on the stock bottle

cannot be relied

upon as the

solution begins decomposing once prepared. For this reason you will need to

take a 1.00 mL aliquot of the stock solution and quench this in cold water. This solution

will then need to be titrated against the standard H

2

SO

4

solution to get the correct sto

ck

concentration of

tert

-

butoxide

. Note also this is

not

the concentration of the (H

3

C)

3

COK at

time zero in the reaction mixture

â

the (H

3

C)

3

COK solution has been mixed with the CH

3

I

solution in the reaction flask. Thus an appropriate calculation needs t

o be done to get the

(H

3

C)

3

COK concentration in the reaction mixture at time zero.

2.

The concentration stated on the bottle for the stock CH

3

I solution can be used but again note

that the time zero concentration of the CH

3

I in the reaction mixture is not th

is value.

Remember the CH

3

I solution is mixed with (H

3

C)

3

COK solution in the reaction flask so an

appropriate calculation needs to be carried out to get the time zero concentration for the

CH

3

I.

Record the initial concentrations of your two solutions and

the standard sulfuric acid as

shown below and d

raw

a

table in your laboratory notebook

or prepare an excel

spreadsheet

.

Initial Concentration of (H

3

C)

3

COK in (H

3

C)

3

COH

Initial Concentration of CH

3

I in (H

3

C)

3

COH

Concentration of standardised H

2

SO

4

You will use the data calculated in the table to draw 2 graphs. A plot or time versus log [CH

3

I]

will give a straight line if the reaction is first order.

A plot of time versus log ([(H

3

C)

3

CO

Ì

] / [CH

3

I]) will give a straight line if the reaction is second

order.

49

Experimental

*

Note that the melting point of (H

3

C)

3

COH is 23

o

C

â

26

o

C. It may solidify if the room

temperature is cool, so keep all solutions warm.

*

Work in pairs for this experiment.

In separate conical flasks, place iodomethane in

tert

-

butanol (200.0 mL) and potassiumtert

-

butoxide intert

-

butanol (20.0 mL). If not already warmed, place the separate solutions in a water

bath (~40

o

C) for a few minutes. Start

timing on

the stop

-

watch as you quickly combine the

solutions, swirling to mix them thoroughly. Place the reaction vessel in the water bath to

maintain constant temperature. Prepare a conical flask containing cold water (20.0 mL). After

10 minutes pipette an aliquot of th

e reaction mixture (10.0 mL) and run it into the cold water to

quench the reaction. Later you can add phenolphthalein indicator and titrate the liberated

hydroxide ion using the standardised sulfuric acid. After removal of each aliquot the pipette

should

be thoroughly rinsed with water and acetone. The pipette can be dried if necessary by

blowing air through it using the house compressed air and appropriate tubing. Remove aliquots

every 10 minutes for the first hour and every 20 minutes for the second h

our. Write the sulfuric

acid titres in your table, carry out all necessary calculations and plot the graphs.

Questions

1.

By what mechanism would you expect the reaction between potassium

tert

-

butoxide

and iodomethane to proceed? Explain your answer and

write the curved arrow

mechanism.

2.

Do your results support your prediction? If not, offer some possible explanations.

3.

Provide a sample calculation of each of the cells in the spreadsheet for one time

interval. Show the formulae used for each calculation

Weekly leaderboard

Homework Help 3,900,000

Chemistry 830,000

Start filling in the gaps now

New to OneClass?Sign up