Materials Science C

Test your knowledge of various Science Olympiad events.
Tesel
Exalted Member
Exalted Member
Posts: 161
Joined: January 30th, 2016, 8:03 pm
Division: C
State: MI

Materials Science C

Postby Tesel » February 8th, 2018, 6:31 am

I was surprised to see that there wasn't a forum for this, so I'll start us off.

Image

A. Give the common name of this compound.

B. Give the strict IUPAC system name of this compound. (Even though the common name is also generally accepted by the IUPAC.)
University of Michigan Science Olympiad Div. C Event Lead

2018 MI Mission Possible State Champions

wethose
Member
Member
Posts: 7
Joined: August 11th, 2017, 4:08 pm
State: -

Re: Materials Science C

Postby wethose » February 13th, 2018, 10:31 pm

A) tert-butylcyclohexane
b) (1,1-dimethylethyl) cyclohexane


Speaking in terms of hybridization, why do alkanes lack isomers?

Tesel
Exalted Member
Exalted Member
Posts: 161
Joined: January 30th, 2016, 8:03 pm
Division: C
State: MI

Re: Materials Science C

Postby Tesel » February 14th, 2018, 6:47 am

wethose wrote:A) tert-butylcyclohexane
b) (1,1-dimethylethyl) cyclohexane


Speaking in terms of hybridization, why do alkanes lack isomers?


Correct on both parts!

Alkanes have structural isomers, of course. However, they do not have geometric isomers. This is because they contain only sigma bonds, which are able to freely rotate between all possible geometric configurations. In terms of hybridization, their carbons form bonds with 4 sp3 hybrid orbitals. Geometric isomers occur when pi bonds (in double and triple bonds) restrict rotation around the sigma bond. To form such geometric isomers, carbon atoms must contain sp or sp2 hybrid orbitals for sigma bonds and p orbitals for pi bonds.

I assume this covers the question, but I will wait for you to verify before I post another question.
University of Michigan Science Olympiad Div. C Event Lead

2018 MI Mission Possible State Champions

wethose
Member
Member
Posts: 7
Joined: August 11th, 2017, 4:08 pm
State: -

Re: Materials Science C

Postby wethose » February 15th, 2018, 1:02 am

Tesel wrote:
wethose wrote:A) tert-butylcyclohexane
b) (1,1-dimethylethyl) cyclohexane


Speaking in terms of hybridization, why do alkanes lack isomers?


Correct on both parts!

Alkanes have structural isomers, of course. However, they do not have geometric isomers. This is because they contain only sigma bonds, which are able to freely rotate between all possible geometric configurations. In terms of hybridization, their carbons form bonds with 4 sp3 hybrid orbitals. Geometric isomers occur when pi bonds (in double and triple bonds) restrict rotation around the sigma bond. To form such geometric isomers, carbon atoms must contain sp or sp2 hybrid orbitals for sigma bonds and p orbitals for pi bonds.

I assume this covers the question, but I will wait for you to verify before I post another question.


Yep! Thanks for catching the structural vs geometric thing.. I'm new to this event lol

Tesel
Exalted Member
Exalted Member
Posts: 161
Joined: January 30th, 2016, 8:03 pm
Division: C
State: MI

Re: Materials Science C

Postby Tesel » February 15th, 2018, 4:52 am

wethose wrote:Yep! Thanks for catching the structural vs geometric thing.. I'm new to this event lol


Not a problem, it was still a good question!

Below is a stress-strain curve characteristic of thermoplastic polymers:

Image

Given that this graph uses engineering stress and strain values, why does the polymer show a rapid decrease in stress after the yield strength, then a plateau, then a gradual increase in stress before fracture?
University of Michigan Science Olympiad Div. C Event Lead

2018 MI Mission Possible State Champions

IcsTam
Member
Member
Posts: 58
Joined: March 1st, 2017, 5:09 pm
Division: C
State: PA

Re: Materials Science C

Postby IcsTam » February 25th, 2018, 10:04 am

Tesel wrote:
wethose wrote:Yep! Thanks for catching the structural vs geometric thing.. I'm new to this event lol


Not a problem, it was still a good question!

Below is a stress-strain curve characteristic of thermoplastic polymers:

Image

Given that this graph uses engineering stress and strain values, why does the polymer show a rapid decrease in stress after the yield strength, then a plateau, then a gradual increase in stress before fracture?


The polymer chains become increasingly oriented with the tensile axis, increasing the strength of the polymer (strain hardening)
Penncrest ‘18
UPenn ‘22
PM me about UPenn, Physics, or anything college or SciOly related!

Tesel
Exalted Member
Exalted Member
Posts: 161
Joined: January 30th, 2016, 8:03 pm
Division: C
State: MI

Re: Materials Science C

Postby Tesel » February 25th, 2018, 11:54 am

IcsTam wrote:The polymer chains become increasingly oriented with the tensile axis, increasing the strength of the polymer (strain hardening)


Correct!
University of Michigan Science Olympiad Div. C Event Lead

2018 MI Mission Possible State Champions

IcsTam
Member
Member
Posts: 58
Joined: March 1st, 2017, 5:09 pm
Division: C
State: PA

Re: Materials Science C

Postby IcsTam » February 25th, 2018, 4:27 pm

What is the Ziegler-Natta catalyst and what is its function?
Penncrest ‘18
UPenn ‘22
PM me about UPenn, Physics, or anything college or SciOly related!

User avatar
Name
Member
Member
Posts: 275
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset

Re: Materials Science C

Postby Name » February 25th, 2018, 5:17 pm

IcsTam wrote:What is the Ziegler-Natta catalyst and what is its function?

Ziegler natta catalyst is used in addition polymerization in order to control tacicity and eliminate branching, allowing to produce certain types of polymers that couldn't have produced otherwise
South Woods MS (5 medals)/Syosset HS (24 medals)
Favorite Past Events: Microbe, Invasive, Matsci, Fermi
Next Year: Astro, Code, hopefully Orni, and maybe Compound
2018-19 highlights
mit- 1st code, 3rd fermi
cornell- 1st fermi
states- 1st fermi, 3rd astro, 3rd code
19 medals

IcsTam
Member
Member
Posts: 58
Joined: March 1st, 2017, 5:09 pm
Division: C
State: PA

Re: Materials Science C

Postby IcsTam » February 25th, 2018, 5:52 pm

Name wrote:
IcsTam wrote:What is the Ziegler-Natta catalyst and what is its function?

Ziegler natta catalyst is used in addition polymerization in order to control tacicity and eliminate branching, allowing to produce certain types of polymers that couldn't have produced otherwise


Correct! Your turn.
Penncrest ‘18
UPenn ‘22
PM me about UPenn, Physics, or anything college or SciOly related!

User avatar
Name
Member
Member
Posts: 275
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset

Re: Materials Science C

Postby Name » February 26th, 2018, 8:37 am

What is vulcanization? What effect does it have on rubber? How does vulcanization molecularly affect the rubber?
South Woods MS (5 medals)/Syosset HS (24 medals)
Favorite Past Events: Microbe, Invasive, Matsci, Fermi
Next Year: Astro, Code, hopefully Orni, and maybe Compound
2018-19 highlights
mit- 1st code, 3rd fermi
cornell- 1st fermi
states- 1st fermi, 3rd astro, 3rd code
19 medals

Tesel
Exalted Member
Exalted Member
Posts: 161
Joined: January 30th, 2016, 8:03 pm
Division: C
State: MI

Re: Materials Science C

Postby Tesel » February 26th, 2018, 9:47 am

Name wrote:What is vulcanization? What effect does it have on rubber? How does vulcanization molecularly affect the rubber?


Vulcanization is a process where natural rubber is heated with sulfur. It causes the rubber to become less sticky, more durable, and more useful. It creates sulfur cross-links between the rubber chains, similar to the curing of thermoplastic polymers.
University of Michigan Science Olympiad Div. C Event Lead

2018 MI Mission Possible State Champions

User avatar
Name
Member
Member
Posts: 275
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset

Re: Materials Science C

Postby Name » February 26th, 2018, 12:33 pm

Tesel wrote:
Name wrote:What is vulcanization? What effect does it have on rubber? How does vulcanization molecularly affect the rubber?


Vulcanization is a process where natural rubber is heated with sulfur. It causes the rubber to become less sticky, more durable, and more useful. It creates sulfur cross-links between the rubber chains, similar to the curing of thermoplastic polymers.

Yup your turn
South Woods MS (5 medals)/Syosset HS (24 medals)
Favorite Past Events: Microbe, Invasive, Matsci, Fermi
Next Year: Astro, Code, hopefully Orni, and maybe Compound
2018-19 highlights
mit- 1st code, 3rd fermi
cornell- 1st fermi
states- 1st fermi, 3rd astro, 3rd code
19 medals

IcsTam
Member
Member
Posts: 58
Joined: March 1st, 2017, 5:09 pm
Division: C
State: PA

Re: Materials Science C

Postby IcsTam » March 3rd, 2018, 3:43 pm

I'm just going to post a question, if that's alright.

1. What is a copolymer?
2. Describe and differentiate between a random, alternating, block, and graft copolymer.
Penncrest ‘18
UPenn ‘22
PM me about UPenn, Physics, or anything college or SciOly related!

Tesel
Exalted Member
Exalted Member
Posts: 161
Joined: January 30th, 2016, 8:03 pm
Division: C
State: MI

Re: Materials Science C

Postby Tesel » March 3rd, 2018, 5:53 pm

IcsTam wrote:I'm just going to post a question, if that's alright.

1. What is a copolymer?
2. Describe and differentiate between a random, alternating, block, and graft copolymer.


Yep, my bad.

Answer
1. A copolymer contains multiple different monomer units.
2A. A random copolymer has monomers randomly ordered, e.g. ABAAABBAABABBBAAB.
2B. An alternating copolymer has regularly alternating monomer units, e.g. ABABABAB.
2C. A block copolymer consists of multiple "blocks" which each contain only one type of monomer, e.g. AAAABBBBAAAAABBB.
2D. A graft copolymer has one type of monomer on the main chain and a different type of monomer on the side chains. In other words, one chain is "grafted" onto the other.


Assuming I'm right, I'll just post the next question, to make sure I don't forget.

Describe the "melting process" for:
1. Amorphous thermoplastic polymers.
2. Crystalline thermoplastic polymers.
3. Thermoset polymers.
University of Michigan Science Olympiad Div. C Event Lead

2018 MI Mission Possible State Champions


Return to “2018 Question Marathons”

Who is online

Users browsing this forum: No registered users and 1 guest