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Acid/base neutralisation reaction

how do i work out the product of H3PO4 + NaOH ? ? ? ?

Well as this is a neutralisation reaction you're goingto make a salt and water. So basically as you're making water, you know that's 2 hydrogens and an oxygen taken care with then you have 2 hydrogens, 4 oxygens, phosphorus and sodium left. This compound then has the formula of NaH2PO4.

H3PO4 + NaOH --> NaH2PO4(aq) + H2O

Reply 2

HG1

Original post by FrooshGuitar

thanks for the helps ,but how would i apply the same method for e.g.

siO2 + NaOH ?

Reply 3

milutin767

Original post by HG1

how do i work out the product of H3PO4 + NaOH ? ? ? ?

technically you could end up with three different salts:
Na3PO4
NaHPO4
Na2H2PO4

however in a level syllabus im pretty sure you would just want Na3PO4 because H3PO4 is a strong acid therefore fully dissociates which leaves you with PO4(3-) ion hence sodium-phosphate :smile:

Reply 4

HG1

Original post by milutin767

Thanks , im still confused as to how these are worked out or do you just have to memeorise them ?

Reply 5

milutin767

Original post by HG1

Thanks , im still confused as to how these are worked out or do you just have to memeorise them ?

well i wouldn't memorise the actual reaction but principle is pretty much the same

H3PO4 is an acid therefore releases protons in solution:
H3PO4---> H+ + H2PO4(-)
H2PO4----->H+ + HPO4(2-)
HPO4(2-)---->H+ + PO4(3-)

so NaOH has only one OH group:
NaOH---->Na+ + OH-

so you can get:
NaH2PO4 (acidic salt)
Na2HPO4 (acidic salt)
Na3PO4 (neutral salt)
(i see a made a mistake in the previous answer sorry about that)

i don't think you need to know that but essentially neutralisation reaction is the one between acid and a base to form a salt and water :smile:

Reply 6

Nayzar

Yeah I tried working them out once and it takes too much effort to make sense of it (though i managed it in the end). Im just gonna learn them

btw i learnt the ionic equaions so i can apply them to several compounds

(edited 7 years ago)

Reply 7

HG1

Original post by Nayzar

hey man could you explain the priciple of how to work these out as my book doesnt have all the ones i need as apparently any combination of acid and base could come up on my exam ?

Reply 8

Nayzar

Original post by HG1

hey man could you explain the priciple of how to work these out as my book doesnt have all the ones i need as apparently any combination of acid and base could come up on my exam ?

its kinda guesswork but basically in the example of H3PO4:
PO4^3- is the main ion and its bonded to 3H+ so it's triprotic (Bronsted-Lowry - donates protons). Therefore those H+ will be replaced by 3 positive charges from the metal its reacting with. eg with NaOH:
H3PO4 + 3Na+ ---> Na3PO4 + 3H+

(edited 7 years ago)

Reply 9

HG1

Original post by Nayzar

its kinda guesswork but basically in the example of H3PO4:PO4^3- is the main ion and its bonded to 3H+ so it's triprotic (Bronsted-Lowry - donates protons). Therefore those H+ will be replaced by 3 positive charges from the metal its reacting with. eg with NaOH:
H3PO4 + 3Na+ ---> Na3PO4 + 3H+

Thanks alot ! that def makes sense , does it work with all acids and bases though ?