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Chemistry: Post your doubts here!

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Can anyone help solve this, I used Mr=MRT/PV but I couldn't get a proper value.

When an evacuated glass tube of volume 200cm^3 is filled with a gas at 300k and 101kPa the mass of the tube increases by 1.06g.

What is the identity of the gas?

A) Argon
B) Krypton
C) Neon
D) Xenon
 
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View attachment 65257Can anyone explain the first point , and why’s its wrong and the third one
Heyy ... I had to ask for help because I was bamboozled by the fact that 1 is not correct. Here's the deal. 1 is wrong because the equilibrium pressure will only be reached once the external pressure (atmospheric pressure) is equal to the internal pressure .Work will be done by the expanding gas until the pressures inside and out even each other . This is an application of some Isobaric Processes Theory I suggest you look that up.

Number 3 can be explained in two ways . The English there was a bit tricky for me 😂😂😂 . (1)Well the expanding gas(from dissociation products) pushes back on the plunger and hence that is the increase in the volume there
(2) There's increase in moles of gases and since moles of gases directly proportional to the volume from PV=nRT thus theres a higher volume than there would be if no dissociation occurred
 
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Heyy ... I had to ask for help because I was bamboozled by the fact that 1 is not correct. Here's the deal. 1 is wrong because the equilibrium pressure will only be reached once the external pressure (atmospheric pressure) is equal to the internal pressure .Work will be done by the expanding gas until the pressures inside and out even each other . This is an application of some Isobaric Processes Theory I suggest you look that up.

Number 3 can be explained in two ways . The English there was a bit tricky for me 😂😂😂 . (1)Well the expanding gas(from dissociation products) pushes back on the plunger and hence that is the increase in the volume there
(2) There's increase in moles of gases and since moles of gases directly proportional to the volume from PV=nRT thus theres a higher volume than there would be if no dissociation occurred
I’m mind blown right now😂😂 that’s such an important pointer right there
Thank you so muchhh. I tried to research about any relationship between the equilibrium pressure and atmospheric pressure , but I couldn’t .
 
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Hello ,
Can anyone help solve this, I used Mr=MRT/PV but I couldn't get a proper value.

When an evacuated glass tube of volume 200cm^3 is filled with a gas at 300k and 101kPa the mass of the tube increases by 1.06g.

What is the identity of the gas?

A) Argon
B) Krypton
C) Neon
D) Xenon
check your conversions of pressure and volume , because I got 130.8 as the answer which I assume is for Xenon
 
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I’m mind blown right now😂😂 that’s such an important pointer right there
Thank you so muchhh. I tried to research about any relationship between the equilibrium pressure and atmospheric pressure , but I couldn’t .
I’m mind blown right now😂😂 that’s such an important pointer right there
Thank you so muchhh. I tried to research about any relationship between the equilibrium pressure and atmospheric pressure , but I couldn’t .
My Pleasure 😊😊

Yeah it doesn't appear much in textbooks but here's where I trust that you will find it

Its a textbook
 
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My Pleasure 😊😊

Yeah it doesn't appear much in textbooks but here's where I trust that you will find it

Its a textbook
I can’t access it tho, but thank you anyway
 
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View attachment 65260

Can someone please solve part c (ii) and explain thanks in advance
c i) a yellow flame is seen . Since there's presence of the Sodium Ion so we expect the colour change when sodium is burnt ...

ii) We expect to see a blue solution. Since the basic CuO will react with the NaHSO4 to give NaSO4 + CuSO4 and water. We know for sure that Copper (ii) Oxide is basic(because it is an oxide of a metal) but you may be unsure about the acidity or basicity of HSO4-. The lewis structure of HSO4- shows that it has a hydrogen atom bonded to an oxygen atom . The Anion may act as a Brownsted Lowry acid and lose this proton(hydrogen) in chemical reactions because it has not undergone full deprotonation.(it would have undergone full deprotonation if it was SO4- . )
*Note that HSO4- is a derivative of SO4-

Therefore overall an acid base reaction will take place and we get a blue solution observed .
 
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¬Meet a Chemistry Academic 2020¬
Organized by ChemSoc & The Chemistry PASS Scheme
Interested in finding more about different themes in chemistry? This is the chance!
The event is open to anyone who has an interest in chemistry or a related field, including, but not limited to, physics, biology, biochemistry, environmental science, education and teaching. This includes students currently studying A/L's as well from any country and is a completely free event!

Register here: https://forms.gle/MzXWCuyDBPhHnWZ8A
Speakers include:

(a)22nd July 2020

1. Dr. David Mills (Inorganic Chemistry) - Inorganic Synthesis, Molecular magnetism & Spectroscopy.

Session suitable for those who have an interest in inorganic chemistry, inorganic spectroscopic analysis, and its applications including in nuclear fuel cycles and data storage.

2. Prof. Peter Budd (Materials Chemistry) - Novel Polymers, 2D materials & Membranes for Molecular Separations.

Session suitable for those who have an interest in materials chemistry, industrial separations and membrane technologies.

3. Dr. Kristy Turner (Chemical Education) - STEM Teaching, portfolio careers & science communication.

Session suitable for those who have an interest in teaching, science writing and communication as well as other careers that are possible after completing a STEM based degree.

4. Prof. Perdita Barran & Dr. Drupad Trivedi (Analytical Chemistry) - Mass spectrometry, chemometrics and it’s applications to biomarker discovery and on tuberculosis.

Session suitable for those who have an interest in analytical science, including mass spectrometry, and its applications in diagnosis of Parkinson's disease and TB.

(b) 23rd July 2020
1. Dr. Nicholas F. Chilton (Theoretical Chemistry) - Quantum Chemistry & Computational Chemistry

Session suitable for those who have an interest in quantum mechanics, science based program development and theoretical chemistry.

2. Prof. Igor Larrosa (Organic Chemistry) - Catalysis & Organic Synthesis

Session suitable for those who have an interest in organic chemistry, including catalysis and organic synthesis.

3. Dr. Nicholas Weise (Chemical Biology) - Biocatalysis, sustainable chemistry & Public Engagement

Session suitable for those who have an interest in enzymes and their applications, sustainable development of existing chemical processes & in public engagement.

Any questions, please feel free to message or email at [email protected]!
 

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But the problem is , isn’t the entalphy change is only needed for C2H2. Here it gives C2H2 and H2
 
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But the problem is , isn’t the entalphy change is only needed for C2H2. Here it gives C2H2 and H2
In the Transformation of carbon and hydrogen to ethyne we need 2 moles of Carbon and 1 mole of hydrogen . The other mole of hydrogen is not used in the reaction and hence the change in enthalpy of that step is zero . I hope you can see in the picture
 

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