Arrange & Explain by Raj #YNWA

bm0900 — 2021-03-16 06:50:24 UTC

Arrange the following alkanes in order of decreasing boiling point. Explain your answer.

2,2-dimethylbutane, hexane, butane

mms1911170130 — 2021-03-16 07:06:21 UTC

hexane, butane, 2,2-dimethylbutane
-the number of carbon atom hexane> butane > 2,2-dimethylbutane
-molecular size of hexane > butane > 2,2-dimethylbutane
-van der Waals forces hexane > butane > 2,2-dimethylbutane. - energy requires to overcome to separate molecules hexane > butane > 2,2-dimethylbutane

m500023 — 2021-03-16 07:09:47 UTC

Hexane, Butane, 2,2-dimethylbutane

Hexane has higher number of carbon atom compared to Butane. Thus, it has higher molecular size and higher molecular surface area. The van der Waals forces are stronger. Thus, more energy required to separate molecules from one another. Thus, Hexane has higher boiling point than Butane.

2,2-dimethylbutane has the lowest boiling point because it has the highest number of branches. Its molecular surface area is the smallest. Therefore, van der Waals forces between the molecules are the weakest. Energy required to separate molecules from one another are the least. Thus, 2-2,dimethylbutane has lower boiling point compared to Hexane and Butane.

m1558740 — 2021-03-16 07:12:20 UTC

mms1911170613 — 2021-03-16 07:13:52 UTC

Hexane > Butane > 2,2-dimethylbutane
- The number of carbon atom in butane is less than hexane while the number of branches of 2,2-dimethylbutane is more than butane.
- Molecular size and molecular surface area becomes smaller.
- van der Waals forces become weaker. Thus, less energy required to separate molecules from one another.
- Therefore, the boiling point of hexane > butane > 2,2-dimethylbutane.

m2537488 — 2021-03-16 07:17:59 UTC

Pavan (S16P12)

In decreasing order :
Hexane, butane, 2,2-dimethylbutane

-Hexane and butane are straight chain alkanes while 2,2-dimethylbutane is a branched alkane.
-The boiling point of butane is lower than hexane because it contains lower number of carbon atoms.
-The molecular size and molecular surface area of butane is smaller than hexane
-Butane has weaker van der Waals forces between molecules compared to Hexane.
-Less energy is required to separate the molecules of butane compared to Hexane.
-2,2- dimethylbutane has lower boiling point than butane because it is a branced alkane.
-The molecular suface area of 2,2-dimethylbutane is smaller than butane.
-The van der Waals forces between the 2,2-dimethylbutane molecules is weaker than butane.
-Thus less energy is is required to separate the molecules.

m2413302 — 2021-03-16 07:18:30 UTC

m10175650 — 2021-03-16 07:19:32 UTC

mms1911170117 — 2021-03-16 07:19:44 UTC

hexane > 2,2-dimethylbutane > butane
- The number of carbon of hexane and 2,2-dimethylbutane which is 6 carbons is higher than the number of carbon of butane which is 4 carbon.
- The number of branch of hexane is zero while the number of branch of 2,2-dimethylbutane is two.
- Hence, the molecular surface of hexane > 2,2-dimethylbutane > butane.
- The strength of van der Waals forces of hexane > 2,2-dimethylbutane > butane.
- The energy needed to separate molecules from one another of hexane > 2,2-dimethylbutane > butane.
- Thus, the boiling point of hexane > 2,2-dimethylbutane > butane.

bm0900 — 2021-03-16 07:22:15 UTC

Arrange the following alkanes in order of increasing boiling point. Explain your answer.

2,2-dimethylheptane, 4-ethylheptane, 2,2,4,4-tetramethylpentane, nonane

m6058626 — 2021-03-16 07:22:45 UTC

Chua Xin Lin
-Hexane > 2,2-dimethylbutane > butane
- Hexane and 2,2-dimethylbutane has the same number of carbon but the number of branch in 2,2-dimethylbutane is more.
- The molecular surface area of 2,2-dimethylbutane is smaller than hexane.
- Hence, van der Waals force in 2,2-dimethylbutane is weaker compared to hexane.
- Less heat is required for 2,2-dimethylbutane to break it's bond compared to hexane.
- Hexane has higher boiling point that butane because hexane has higher number of carbon causes it's molecular surface area greater than butane.
-Thus, hexane has stronger van der Waals force than butane.
- More heat is required by hexane to break bonds compare to butane.

m9052742 — 2021-03-16 07:25:39 UTC

Arrangement : Hexane, 2,2-dimethylbutane, butane

Explanation

Hexane and 2,2-dimethylbutane

•Hexane has the same number of carbon atoms as 2,2-dimethylbutane but 2,2-dimethylbutane has more branches than hexane, hence molecular surface area becomes smaller. Hence Van Der Waals forces between the molecules in 2,2-dimethylbutane is weaker than hexane, hence less energy required to separate the molecules from one another. Hence boiling point of hexane is higher than 2,2-dimethylbutane

2,2-dimethylbutane and butane.

• number of carbon atoms in 2,2-dimethylbutane is higher than in butane. Hence molecular size and molecular surface area of 2,2-dimethylbutane Is larger than butane , hence Van Der Waals forces between the molecules in 2,2-dimethylbutane is stronger than in butane. More energy required to separate the molecules from one another in 2,2-dimethylbutane than butane. Hence boiling point of 2,2-dimethylbutane is higher than butane.

m1474778 — 2021-03-16 07:29:01 UTC

hexane > butane > 2,2-dimethylbutane

-Butane and 2,2-dimethylbutane contain four carbon atoms while hexane contain six carbon atoms.
-Boiling point increases with the increasing number of carbon atoms. Hexane has the largest contact surface area. Thus, it has the strongest van der Waals forces and the highest boiling point.
-Branching alkanes decreases the surface area of molecules. 2,2-dimethylbutane has two branches than butane. It has the smallest contact surface area and the weakest van der Waals forces. Thus, 2,2-dimethylbutane has the lowest boiling point.

mms1911170768 — 2021-03-16 07:30:52 UTC

Hexane > 2,2-dimethylbutane > butane

•Butane is made up of 4 carbons while hexane and 2,2-dimethylbutane are made up of 6 carbons

•Hexane and butane has no brunch while 2,2-dimethylbutane has two branches.

•The molecular weight of butane is smaller than hexane and 2,2-dimethylbutane.

•The strength of Van der Waals forces in butane is weaker compared to hexane and 2,2-dimethylbutane.

•The energy needed to overcome the Van der Waals in butane is weaker compared to hexane and 2,2-dimethylbutane.

•Thus, the boiling point of butane is lower compared to hexane and 2,2-dimethylbutane.

m3535478 — 2021-03-16 07:31:32 UTC

Hexane,2,2-dimethylbutane,butane
-The no. of C atom for hexane and 2,2-dimethylbutane was same which is 6 carbon while no. of C atom for butane was lower which is 4 carbon.
-Thus butane has the lower boiling point compared to hexane and 2,2-dimethylbutane.
-Hexane has the highest boiling point because it is unbranced alkanes compared to 2,2-dimethylbutane which is branched alkanes.
-Branched alkanes has lower boiling point compared to the unbranched because branched alkanes have smaller molecular surface area (molecules are more compact) therefore Van der Waals forces decreases,thus less energy required to separate molecules from one another,which gives lower boiling point.
-Thus,hexane has the highest boiling point compared to 2,2-dimethylbutane and butane.

m1556662 — 2021-03-16 07:31:32 UTC

hexane , 2,2-dimethylbutane, butane

because hexane and 2,2-dimethylbutane have the highest carbon atoms which is 6 compare with butane which is 4.
Therefore butane have the lowest boiling point.
2,2-dimethylbutane have lower boiling point compare with hexane because it have a 2 branched while hexane is unbranched alkanes.
When there have a branched alkanes the molecular surface area will be small, therefore van der walls forces is decreases.
Thus, less energy required to separate molecule from one another.

mms1911170258 — 2021-03-16 07:34:45 UTC

m9052742 — 2021-03-16 07:39:10 UTC

Arrangement : 2,2,4,4-tetramethylpentane < 2,2-dimethylheptane<4-ethylheptane
Explanation
•No of carbon atoms in 2,2,4,4-tetramethylpentane =2,2-dimethylheptane=4-ethylheptane=nonane which is 9
•No of branches of 2,2,4,4-tetramethylpentane>2,2-dimethylheptane>4-ethylheptane>nonane
•Molecular surface area of 2,2,4,4-tetramethylpentane<2,2-dimethylheptane<4-ethylheptane•van Der Waals forces between molecules of 2,2,4,4-tetramethylpentane<2,2-dimethylheptane<4-ethylheptane•energy required to separate molecules from one another in 2,2,4,4-tetramethylpentane<2,2-dimethylheptane<4-ethylheptane•Hence boiling point of 2,2,4,4-tetramethylpentane < 2,2-dimethylheptane<4-ethylheptane

bm0900 — 2021-03-16 07:41:44 UTC

For the first question..you have to categorise them according to molar mass...and then isomeric compounds..yg ada branch dan tak de branch😀✌🏼

bm0900 — 2021-03-16 07:42:38 UTC

Baru susun compounds sama ada ascending atau descending

mms1911170258 — 2021-03-16 07:46:02 UTC

m1558740 — 2021-03-16 07:46:24 UTC

2.
2,2,4,4-tetramethylpentane<2,2-dimethylheptane<4-ethylheptane
2,2,4,4-tetramethylpentane
-has the lowest boiling point because it has the smallest number of C atom and has branched alkane.
-Has the smallest molecular size and molecular surface area
-Van der Waals forces between the molecules is the weakest
-Less energy needed to seperate the molecules

Nonane
-has the highest boiling point because it has the largest number of Carbon atom and unbranched.
-Molecular size and surface area is the largest
-Van der Waals forces between molecule become stronger
-More energy required to seperate molecules from one another

2,2-dimethylheptane<4-ethylheptane
-has more number of branches that attached to parents chain.
-Have smaller molecular surface area as the molecules are more compact
- Van der Waals forces between molecules weaker
-Less energy required to seperate molecules from one another.

m6058626 — 2021-03-16 07:48:08 UTC

-2,2-dimethylheptane, 4-ethylheptane, 2,2,4,4-tetramethylpentane, nonane.
- 4-ethylheptane has lesser number of branches compared to 2,2-dimethylheptane.
-Hence, 4-ethylheptane has bigger molecular surface area compared to 2,2-dimethylheptane.
- Van der Waals force in 4-ethylheptane is stronger than 2,2-dimethylheptane.
-More energy is need by 4-ethylheptane to separate molecules from one another compared to 2,2-dimethylheptane.
- Boiling point of 4-ethylheptane higher than 2,2-dimethylheptane.

-2,2,4,4-tetramethylpentane has higher boiling point than 4-ehtylpentane because it has higher number of carbon.
- 2,2,4,4-tetramethylpentane has higher molecular surface area hence strength of Van der Waals forces is stronger than 4-ethylpentane.
- More energy is required to separate the molecules from one another by 2,2,4,4-tetramethylpentane compared to 4-ethylpentane.

-Nonane has higher boiling point than 2,2,4,4-tetramethylpentane because nonane is linear alkane, which does not has branches.
-This causes surface area of nonane bigger than 2,2,4,4-tetramethylpentane.
- Van der Waals force in nonane is stronger than 2,2,4,4-tetramethylpentane.
- More energy is required by nonane to separate molecules from each other compared to 2,2,4,4-tetramethylpentane.

ms1911170635 — 2021-03-16 07:50:48 UTC

Nur Sabrina S16T12

mms1911170768 — 2021-03-16 07:50:59 UTC

Let,

A: 2,2-dimethylheptane
B: 4-ethylheptane
C: 2,2,4,4-tetramethylpentane
D: nonane

•Compound A,B,C and D are isomeric alkanes.

•All compounds given are made up of 9 carbons and have same molecular weight.

•Compound D haa no branches, compound B has one branches, compound A has two branches while compound C has 4 branches.

•Size of compound D is larger compared to compund A, B and C.

•The strength of Van der Waals forces of compound D is stronger than compound A, B and C.

•The molecular contact surface are of compound D is larger than compound A, B and C.

•Thus, the boiling point increasing from compound C to A to B and to D.

2,2,4,4-tetramethylpentane < 2,2-dimethylheptane < 4-ethylheptane < nonane

Peace ✌🏻

ms1911170635 — 2021-03-16 07:51:04 UTC

bm0900 — 2021-03-16 07:58:49 UTC

So, conclusion for today, kita kena tengok SAIZ MOLEKUL dulu.. or kira bilangan carbon atom. More C atoms higher boiling point..kemudian tengok bilangan BRANCH..lagi banyak branch, lower boiling point...

bm0900 — 2021-03-16 08:00:07 UTC

Sticker berwarna merah boleh dijadikan template answer for boiling point...for molar mass and branch discussions ONLY

bm0900 — 2021-03-16 08:03:12 UTC

Answer this and post!😎

m2413302 — 2021-03-16 08:08:29 UTC

Soalan kedua

m6058626 — 2021-03-16 12:03:13 UTC

L is aldehyde, M is carboxylic acid while N is alcohol.
- Boiling point increases from L to N then M.
- L has the lowest boiling point because it is a polar compound that have dipole-dipole forces between molecule.
- N has higher boiling point than L because it has hydrogen bonding and van der Waals force. This causes more energy is needed by N compared to L to break it's bonds.
- M has the highest boiling point because it's molecules are arranged closely packed and it forms a stable hydrogen-bonded dimer which needs more energy to break bonds compared to compound N and L.

mms1911170613 — 2021-03-16 13:48:44 UTC

L is aldehyde, M is carboxylic acid and N is alcohol.
Boiling point: L < N < M
- M has the highest boiling point due to its molecules are arranged closely packed which causes the ability to form stable hydrogen bonded dimers between molecules. Thus, more energy is needed to overcome the strong hydrogen bonding.
- N has the higher boiling point than L due to the ability to form hydrogen bond between molecules. L has the lowest boiling point because it is a polar molecule and thus only dipole-dipole forces existed between molecules. Hydrogen bonding in N is relatively stronger than dipole-dipole forces in L.
- Therefore, the ascending order of boiling point is L < N < M

m9052742 — 2021-03-16 15:44:11 UTC

Arrangement : L
Explanation
• Molecule M is a carboxylic acid whereas molecule L and N are aldehydes and alcohols respectively. Molecules of Carboxylic Acids are arranged in a closely packed manner hence, enabling formation of stable hydrogen bonds which forms dimers between molecules . Since more energy is required to overcome hydrogen bonds, the boiling point of Carboxylic Acids (M) are higher than aldehydes (L) and alcohols (N).

•Meanwhile, N , which is an alcohol has a higher boiling point than L, which is an aldehyde because alcohol molecules are held together by stronger hydrogen bonds , which needs higher energy to overcome when compared to the aldehyde molecules' weaker dipole-dipole forces as aldehydes are polar compounds. Hence the boiling point of L is higher than N

•Thus, arrangement of boiling point in increasing order : L

bm0900 — 2021-03-17 02:06:45 UTC

Less energy required to overcome attractive forces between 2,2-dimethylbutane molecules.

bm0900 — 2021-03-17 02:23:29 UTC

Aldehyde & ketone - generally van der waals forces

Specifically - dipole dipole forces

bm0900 — 2021-03-17 02:34:41 UTC

bm0900 — 2021-03-17 02:48:51 UTC

Alkane/Alkene/benzene - VDWF@ LF
Haloalkane - dipole-dipole forces
Alcohol - hydrogen bond
Carbonyl - dipole-dipole forces
Carboxylic acid - hydrogen bond in dimer
Amines - hydrogen bond
Amino acid - hydrogen bond

bm0900 — 2021-03-17 02:51:23 UTC

m2413302 — 2021-03-17 03:00:21 UTC

bm0900 — 2021-03-17 03:25:10 UTC

Arrange the following compounds in the increasing order of acidity. Explain.

Ethanoic acid, phenol, 2-chloroethanoic acid ethanol, ethanol

m681483 — 2021-03-17 12:58:32 UTC

Ascending order of acidity
Ethanol < phenol < ethanoic acid < 2-chloroethanoic acid

-2-chloroethanoic acid has highest acidity in water because it consist of Cl as an electron withdrawing group(EWG)
-EWG stabalises the carboxylate ion through inductive effect by withdrawing electron density from carboxylate ion.
-The electron only delocalise between two similar oxygen atom in carboxylate ion which from resonance stabalization.
-Ionisation of 2-chloroethanoic acid shift forward produces more H+ ion which increase the acidity.

-Acidity of ethanoic acid is higher than phenol and ethanol because carboxylate ion of ethanoic acid is resonance stabilised whereby electrons are delocalised over two similar electronegative oxygen atom.
-Wherease in phenoxide ion of phenol, electrons are delocalised within the benzene ring.
-The resonance structure of carboxylate ion is more stable than the phenoxide ion.
-Hence, ethanoic acid has higher acidity as compare with phenol.

-Ethanol is the least acidic compound because electrons are localised at oxygen atom in alkoxide ions only.

2021-03-17 13:31:30 UTC

Increasing order of acid (ATIKAH)
Ethanoic acid=A, B=phenol ,C=2-chloroethanoic acid, D=ethanol

DA•CL is an electron withdrawing (EWG)
•The presence of Cl in A stabilises the carboxylate ion through inductive effect by EWG density from carboxylate ion.
•this makes,less negative charge is delocalised over the oxygen atom of the ion. Therefore, morr stable anion is formed which akes the acid stronger.

B• carboxylate ion of compound A is resonance stabilised whereby electrons are delocalised over two electronegative oxygen atoms.
•whereas in phenoxide ion, the electron ls are delocalised within the benzene ring.
•the resonance structure of carbixylate ion is more stable than phenoxide ion. Therefore, A is more acidic than B.

B• B is the least acidic compare to other due to the electrons are localised at oxygen atom in alkoxide ions.

2021-03-17 16:27:44 UTC

2021-03-17 16:27:50 UTC

adwd

2021-03-17 16:27:51 UTC

dwdw

2021-03-17 16:47:19 UTC

Ascending order of acidity (fikriyah)
Ethanoic acid = A ,phenol = B ,2-chloroethanoic acid = C ,ethanol = D

Arrangement: D
A- Cl is an electron withdrawing group (EWG), reduce the electron density of O-H.
-thus the O-H bond becomes weaker and H+ can be easily released.
-therefore a more stable anion is formed which makes compound C stronger.

D- compound D less acidic than B due to the electrons are localised at oxygen atom in alkoxide ions.

B-the electron in carboxylate ion of compound A are delocalised between two oxygen atoms which stabilises the carboxylate ion and promotes the release of H+.
-due to the resonance stabilisation of the carboxylate ion, A is more acidic than B

m1983082 — 2021-03-17 17:58:51 UTC

ACIDITY
Ethanol < phenol < ethanoic acid < 2-chloroethanoic acid

-2-chloroethanoic consist Cl is an electron acid that has highest acidity EWG which is electron withdrawing group

-EWG stabilises the carboxylate ion through inductive effect by EWG density from carboxylate ion

-Ionisation of 2-chloroethanoic acid produces more H+ ion which increase the acidity.

-Hence the 2-chloroethanoic acid is the most stronger acid

-Acidity of ethanoic acid is higher than phenol and ethanol

-Carboxylate ion of ethanoic acid is resonance stabilises because the electrons are delocalised over two similar electronegative oxygen atom.

-Besides that, in phenol, there have phenoxide ion.

-Electrons are delocalised within the benzene ring.

-The stability of resonance structure of carboxylate ion > phenoxide ion.

-Therefore, ethanoic acid has higher acidity as compare with phenol.

-Ethanol is the least acidic because electrons are localised at oxygen atom in alkoxide ions

So the arrangement:
ethanol

2021-03-17 21:38:13 UTC

Increasing order of acidity (AMZAR)

•The acidity increase from Ethanol
•2-chloroethanoic acid has more acidity than Ethanoic acid because 2-chloroethaoic acid has electron withdrawing group(EWG) with is Cl.

•Cl stabilises the carboxylate ion through inductive effect by withdrawing electron density from the carboxylate ion. Because of that, the oxygen atom of the has less negative charge that delocalised over them.

•Thus, 2-chloroethanoic acid can form more stable ion which makes the acid stronger compared to ethanoic acid.

•Carboxylate ion of ethanoic acid is resonance stabilised whereby the electrons delocalised over 2 electronegative oxygen atoms.

•In phenoxide ion which in Phenol, the electrons are delocalised within the benzene ring.

•The resonance structure of carboxylate ion is more stable than phenoxide ion which makes Ethanoic acid more acidic than Phenol.

• Ethanol has the lowest acidic compared to 2-chloroethanoic acid, Ethanoic acid and Phenol because the electron delocalised at oxygen atom in alkoxide ion. Therefore, Ethanol has the lowest acidic among the others.