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AnAn

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1) a solution of hydrochloric acid was chown to have a pH of approximately 1.2 but the accurate concentration was not know. Addition of 100mL of silver nitrate solution to 100mL of hte hydrochloric acid produced a white precipitate of silver chloride with a dried weight of 0.861 g.
a) estimate the concentration of the hydrochloric acid from the pH

b) give an ionic equation for the precipitation reaction.

c) the pH of the solution remaining after filtration of the precipitate was found to be approximately 1.5. account for this observation. No calculation are necessary

2) why is use of the hydronium ion more appropriate in chemical equation than the hydrogen ion??
 

xiao1985

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a) since hydrochloric acid is a strong acid and ionises to completion, pH = - log[H<sub>3</sub>O]<sup>+</sup>

therefore, using ur calculator, it should be 6.31 x 10<sup>-2</sup>mole/L...

b)Ag<sup>+</sup>(aq) + Cl<sup>-</sup> (aq) --> AgCl (s)

c) probably the added water with agcl diluted the original acid...

2) because essentially, hydrogen ions ionises water molecules to form hydromium ions... also i believe it take into account that degree of ionisation depends on the solvent as well...
 
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spice girl

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Originally posted by AnAn
c) the pH of the solution remaining after filtration of the precipitate was found to be approximately 1.5. account for this observation. No calculation are necessary
you've diluted the acid when you added the silver nitrate in. that's why [H+] is decreased and hence pH rises
 

AnAn

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thx everybody^^
i hv one more question to help..

Lowry spills an unlabelled bottle in the chemistry lab. as he is doing an acid/base practical he suspects it is either an acid or a base. what would be a good method for cleaning it up? ( suggest a chemical the could use and give uquations to explain your reasoning)
 

~*HSC 4 life*~

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Originally posted by AnAn
thx everybody^^
i hv one more question to help..

Lowry spills an unlabelled bottle in the chemistry lab. as he is doing an acid/base practical he suspects it is either an acid or a base. what would be a good method for cleaning it up? ( suggest a chemical the could use and give uquations to explain your reasoning)
use an amphoteric substance such as Al2O3 which can act as an acid or a base so it can neutralise this unknown substance then you can clean it up
 

CM_Tutor

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The usual choice for acidic / basic spills is sodium hydrogencarbonate.

Lactic acid is 2-hydroxypropanoic acid, CH<sub>3</sub>-CH(OH)-COOH
 

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