[Shahab Mirza]

answer is acidic , but how to get that answer , i mean how we know that it is acidic?

[mjc123]

What is the definition of an acid?

[Shahab Mirza]

What is the definition of an acid?

bro , acid =a chemical species that donates protons or accepts , or donates or accepts hydrogen ion ,

but tell me answer to that questions sir, i want to know?

[orgopete]

Let me guess the question, how can  silver replace a proton without using a strong base to make the anion first? If so, the look at my answer in this thread:

http://www.chemicalforums.com/index.php?topic=76622.msg279103#msg279103

[AromaticAcrobatic]

What is the definition of an acid?

bro , acid =a chemical species that donates protons or accepts , or donates or accepts hydrogen ion ,

but tell me answer to that questions sir, i want to know?

"Bro" you dont need 2 ways of describing a bronsted-lowry definition of an acid.
Also, when does Carbon have 6 bonds?
Lastly, take the toga off, put a lab coat on, show some effort and read alittle bit more. I would suggest starting with internuclear distances of Alkynes for this particular problem.

[mjc123]

How would internuclear distances help?

[Shahab Mirza]

So according to my work , i assume that  Because there is Hydrogen ion present in HNO3. hence it is acid. if i am wrong plz correct me

[orgopete]

While ionization of HNO3 does indicate it is an acid, this is not the same as acetylene. I also would not have worded this question in the way indicated. While the hydrogens of acetylene are acidic in the sense that the acidity of the hydrogens of HF, H2O, NH3, and CH4 can also be determined. That is different than determining the equilibrium of acetic, nitric, or sulfuric acid in water. In water, the hydrogens of acetylene are not removed to form acetylide anions and hydronium cations. In that sense, I would not have labeled the acetylene hydrogens as acidic. The net reaction having taken place are the result of replacing the CH hydrogens with a silver atom. The electrons remain with the carbon in that reaction, so a proton was lost in the reaction. In that sense, it is similar to an acid. However, if an alkyl bromide is treated with sodium ethoxide, a proton is also lost in forming an alkene, but we do not describe the alkyl hydrogens as acidic.

What I wished to point out is that the pKa of an alkane is much too high for an alkoxide to remove them in any equilibrium reaction. The bromine atom must in some way alter the pKa of the hydrogens in order for this reaction to take place. I argue this must also be the case for the acetylene hydrogens. If silver nitrate were replaced with sodium nitrate, the product would not be sodium acetylide and nitric acid. Silver is known to complex with alkenes and acetylenes, so it may not be surprising that a complexation may alter the net acidity. I argue it is the complex that enables the acetylene hydrogens to be removed.

[Shahab Mirza]

While ionization of HNO3 does indicate it is an acid, this is not the same as acetylene. I also would not have worded this question in the way indicated. While the hydrogens of acetylene are acidic in the sense that the acidity of the hydrogens of HF, H2O, NH3, and CH4 can also be determined. That is different than determining the equilibrium of acetic, nitric, or sulfuric acid in water. In water, the hydrogens of acetylene are not removed to form acetylide anions and hydronium cations. In that sense, I would not have labeled the acetylene hydrogens as acidic. The net reaction having taken place are the result of replacing the CH hydrogens with a silver atom. The electrons remain with the carbon in that reaction, so a proton was lost in the reaction. In that sense, it is similar to an acid. However, if an alkyl bromide is treated with sodium ethoxide, a proton is also lost in forming an alkene, but we do not describe the alkyl hydrogens as acidic.

What I wished to point out is that the pKa of an alkane is much too high for an alkoxide to remove them in any equilibrium reaction. The bromine atom must in some way alter the pKa of the hydrogens in order for this reaction to take place. I argue this must also be the case for the acetylene hydrogens. If silver nitrate were replaced with sodium nitrate, the product would not be sodium acetylide and nitric acid. Silver is known to complex with alkenes and acetylenes, so it may not be surprising that a complexation may alter the net acidity. I argue it is the complex that enables the acetylene hydrogens to be removed.

Thanks for reply , I can understand the deepness of your concepts by you know sir, that only 1 min is given to us to solve such questions in the examination hall, how can we go that deep, we have to figure our quick term solution.

[mjc123]

In that case you just say that acetylene is acting as an acid by giving up protons; they can't be expecting anything more profound.

[Shahab Mirza]

In that case you just say that acetylene is acting as an acid by giving up protons; they can't be expecting anything more profound.

thanks, but what if we describe it like this . 
CH3 ≡  CH + 2AgNO3 → AgC ≡  CAg + "2HNO3" - here we can see that NO3 has Hydrogen infront and it can act as a acid ?
correct me if i m wrong

[Shahab Mirza]

I know that HNO3 is an acid but it has weak base , and in presence of hydrogen it become acid, is this thing has to do something with answer?

[mjc123]

No, it has nothing to do with the answer, the question was what property of ACETYLENE was being demonstrated.
And you are still getting the formula of acetylene wrong. It is HC≡CH.

[AromaticAcrobatic]

How would internuclear distances help?

If the internuclear distance is small, there is more of an attraction from the carbon nucleus to the electron of the Hydrogen atom. Which would leave a proton hanging out. Hence, the acidity of Alkynes.

I had a long day and am kind of beat but if anyones interested I could find the pgs of the book I'm referring to and reference it.
 

[Shahab Mirza]

Thank , but this answer is too deep, short explaination will work. :/