Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: sharbeldam on September 27, 2020, 11:23:26 AM
-
How to distinguish between NaHSO4 and Na2SO4 in lab using these reactants in this table?
I looked up every reaction online, nothing helps!! please give me a hint.
we can only use our eyes to know the difference between the two colorless tubes using these reactants in table.
for instance if i use bacl2 , they will both form white percipitate which doesnt help...etc.
-
What do you know about to detect sulfates?
You found BaCl2. Great. So you know both are sulfates.
What does it mean if a salt contain hydrogenatoms regarding pH?
Which of the substances could be used if something is acidic?
Answer this questions, by the way we do not solve homeworks, without your own atempt.
-
they both contain sulfates tho so bacl2 wont work as i mentioned. This is not homework sir, i know the site rules, Im trying to help someone solving this question, i gave my try for the first reactant, i tried to see the products of them all.
I dont want you to solve anything for me, thanks
-
I changed a little bit the answer above. But anyway, why the other one dont do the work by him/her self.
-
I dont understand, what is the problem of me helping someone? i spend most of my time helping people and sometimes i get help from this great site.
we can only use eyes, so indicators dont work, for instance if i use NaOH, both solution will stay colorless.
-
You can use your eyes, there is one substances what change dramatically if you add it, which could it be?
This one is also used in the kitchen.
-
you mentioned in your hint the acidic compound so i think your talking about adding a base, is there another base than NaOH?
kitchen... baking soda?
i appreciate your help btw.
-
Compare the acidity constants of carbonic acid with K2 of sulfuric acid.
-
you mentioned in your hint the acidic compound so i think your talking about adding a base, is there another base than NaOH?
kitchen... baking soda?
i appreciate your help btw.
NaOH doesnt help because no indicator present.
Yes correct baking soda.. Which one is the baking soda here? Do you know effervescent powder? What happens if you add the compound to the hydrogensulfat.
-
well baking soda is NaHCO3, it should release CO2 with the HSO4? and does nothing with Na2SO4?
-
Yes correct you will see a lot of bubbles and foam.
-
Thank you :)
-
Compare the acidity constants of carbonic acid with K2 of sulfuric acid.
If I have two tubes with two sulfates, how should it help if I look up the K2 values of carbonic acid and sulfuric acid. If I find them in a table how to go further..
-
we can only use eyes, so indicators dont work
This is a rather strange statement, plenty of pH indicators that work by changing colors. They are not lsited between substances that can be used, but pH strip would be my tool of choice here.
for instance if i use NaOH, both solution will stay colorless.
NaOH is not an indicator, I am not sure why you mention it here.
-
If I have two tubes with two sulfates
You don't have two tubes with two sulfates, you have a tube with a sulfate and a tube with hydrogensulfate.
-
Hydogensulfat is also a sulfate, it dissociates. Why would it react with Barium ions, the precipitate is Bariumsulfate not Bariumhydrogensulfate.
Even Sulfuric acid is a sulfate. Dihydrogensulfate.
The exercise was to use the given chemicals in the table to figure out, which chemical is in the two samples. No indicator to use.
-
Barium hydrogen sulfate can be obtained from barium sulfate in concentrated sulfuric acid. When diluted with water, barium sulphate will precipitate.
-
That is possible of course. But here we have two aquaeous samples.
I answered because we don't have two sulfate was told and this I disagree.
-
One solution is highly acidic, the other is neutral, that's what is important here. You can be nitpicky about whether these are both sulfates, but your question about why to compare dissociation constants suggested you are overlooking the most important property by which these solutions differ.
-
Everything ok, what you are saying, nur it doesnt help if I have the two samples in the hand.
If I know the two K values, what to do next.
-
The stronger acid replaces the weaker acid, HCO3- gets protonated and decomposes, this is exactly a HS level reasoning necessary here. TBH, knowing your level of expertise I am not sure if you are not trolling now.
-
I am not trolling. We have two tubes with one of sodium sulfate and one of sodium hydrogen sulfate.
A list of some chemicals are given to find out what is what.
The TES picked Bariumchloride, what is ok to determine sulfate. Also he want to take NaOH, but this is without indicator or pH probe not possible, to get a result.
At the end I gave a hint for the baking soda, which would react with the hydrogen sulfate.
The miracle is solved.
Between AWK came up with the discussion of k values of carbonic acid and sulfuric acid. But this will not help, if the TES don't know what is going on. It would be same we you know the a melting point of both but they are dissolved., if not can heat up. Probably it is a paperwork and no lab exercise.
Carbonate came into the rule after baking soda was picked up.
My answer was still, what to do with a k value if carbonate is not in the game.
-
My hint regarding the acidity constants of carbonic and sulfuric acid (K2) is the theoretical basis for selecting NaHCO3 for the NaHSO4 test.
Students learn about acid strength (acidity constants) and how they apply to predict the direction of chemical reactions at the very beginning of general chemistry. You probably missed something in your study - carbonic acid contains two active protons.
-
You are right, but before to do so has to have the expierence to pick the right one.
Some people pick maybe Permanganate or copper sulfate, what of course makes no sense.
So given two samples and the list of chemicals. Do you check all physical parameters of each to find out what is for? In my case no. The expierence and the practise is to know that sodiumhydrogencarbonate release gas CO2. Prepared my self candy with strawberry an citric acid and baking soda and not looking up some k values.