[lazyndnkid]

Which of the following gases is easier to liquefy.
CH4 or SiH4
the answer is SiH4
but i dont understand why?
I was thinking since they are both similar compounds the lower molar mass would be easier to liquefy.

[CollisionTheory]

CH4 is easier becaue its got a lower molar mass than Si in it self and as it is alkanes are a group that are easier to liquefy the highest boiling point of an Alkane gas would be around 79 C so thats why its CH4

[Borek]

CH4 is easier becaue its got a lower molar mass than Si in it self and as it is alkanes are a group that are easier to liquefy the highest boiling point of an Alkane gas would be around 79 C so thats why its CH4

Interesting answer, but completely wrong, especially taking into account that SiH₄ is easier to liquefy with boliling point at -112 deg C (as compared to -162 deg C of methane), so much, much lower than 79 deg C you suggest (which is - BTW - boling point of ethanol).

[Astrokel]

sorry, but i don't get the basic concept.

when talking about liquefy, its talking about substance becoming liquid.

melting or condensation? I guess its talking about condensation since both are gases at room temp?

If so why is boiling point being discussed?

kelvin 

[Borek]

Condensation and boiling are two sides of the same coin.

Take water - it boils at 100 deg C. It also starts to condense in the same temperature.

Same happens to each other liquid/vapor pair.

[Astrokel]

Condensation and boiling are two sides of the same coin.

Take water - it boils at 100 deg C. It also starts to condense in the same temperature.

Same happens to each other liquid/vapor pair.

Thx for the concept! 

Am i right to say when ease of liquefy is being compared, it is necessary to compare the strength of intermolecular forces?

In my school, i've learnt how Size of electrons cloud, 'Packing' of the molecules and the Ease of polarizability affects the intermolecular forces.

Im thinking, size of electrons cloud is not applicable in this case, and 'Packing' is also not since CH4 molecules are smaller than that of SiH4.

Therefore, it left me with ease of polarizability. But i do not get the idea of what is the meaning of ease of polarizability. I've checked up on wiki it is how easy an electron cloud is being distorted. How is it applicable to the case of SiH4 and CH4? Does it refer to the ease of forming Si4+?

kelvin

[Borek]

Number of electrons plays very important role here. Molecule size as well.

[Astrokel]

Number of electrons plays very important role here. Molecule size as well.

There are more electrons in SiH4 than CH4, therefore larger electron clouds, electron clouds more easier to be distorted, thereby increasing induced dipole-dipole attractions?

SiH4 has larger molecular size than CH4, therefore increases the surface area of contact with other SiH4 molecules, hence increases the induced dipole dipoled attractions.

But all these suggest SiH4 has stronger intermolecular forces than CH4, hence ease of liquefy is harder.

Thx Borek, and sorry lazyndnkid for sorta snatching your post 

[lazyndnkid]

its cool kelvin,
but no1 really answered my question. I also believed that CH4 is easier to liquefy. But on my review the answer key says SiH4 is the right answer.
Feel free to add tot he post please

[Astrokel]

hey!

anyone could point me out for this qn?

thx heaps 

K

[ayu]

yes. it's SiH4

[Astrokel]

why? 

[JGK]

Number of electrons plays very important role here. Molecule size as well.

There are more electrons in SiH4 than CH4, therefore larger electron clouds, electron clouds more easier to be distorted, thereby increasing induced dipole-dipole attractions?

SiH4 has larger molecular size than CH4, therefore increases the surface area of contact with other SiH4 molecules, hence increases the induced dipole dipoled attractions.

But all these suggest SiH4 has stronger intermolecular forces than CH4, hence ease of liquefy is harder.

Surely from your reasoning, if SiH4 molecules attract each other more and have stronger interractions between molecules than CH4, SiH4 would form a liquid more easily than CH4.

[Astrokel]

Number of electrons plays very important role here. Molecule size as well.

There are more electrons in SiH4 than CH4, therefore larger electron clouds, electron clouds more easier to be distorted, thereby increasing induced dipole-dipole attractions?

SiH4 has larger molecular size than CH4, therefore increases the surface area of contact with other SiH4 molecules, hence increases the induced dipole dipoled attractions.

But all these suggest SiH4 has stronger intermolecular forces than CH4, hence ease of liquefy is harder.

Surely from your reasoning, if SiH4 molecules attract each other more and have stronger interractions between molecules than CH4, SiH4 would form a liquid more easily than CH4.

Hey, thx for it, i got it now 

sorry for the mislook

kelvin