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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: Minimalist on November 10, 2012, 10:10:53 pm

Title: Question about diluting acidic solution.
Post by: Minimalist on November 10, 2012, 10:10:53 pm

Not sure if this is on the course, but if you have 10mL 6pH solution if HCl and and dilute it to 1000mL, what is the new pH? Thanks

Title: Re: Question about diluting acidic solution.
Post by: dfgjgddjidfg on November 10, 2012, 10:42:58 pm

approximately 8

Title: Re: Question about diluting acidic solution.
Post by: Shenz0r on November 10, 2012, 10:46:55 pm

You diluted it by a factor of 100, so you move two units up, giving a new pH of 8. This only works for strong acids though.

Title: Re: Question about diluting acidic solution.
Post by: Minimalist on November 10, 2012, 11:06:36 pm

But 8 implies it's basic... surely that's not possible??

Title: Re: Question about diluting acidic solution.
Post by: emiinaaa on November 10, 2012, 11:36:03 pm

Because the HCl is present in the solution at such a low concentration (10^-6), the main reaction occuring in that beaker or whatever is the self ionisation of water rather than the HCl + H₂O --> H₃O⁺ + OH^- reaction, making it essentially neutral, ie. pH close to 7.
I may be wrong, but this is how a similiar question that I've done was approached.

Title: Re: Question about diluting acidic solution.
Post by: kenhung123 on November 11, 2012, 01:31:27 am

Quote from: Minimalist on November 10, 2012, 11:06:36 pm

But 8 implies it's basic... surely that's not possible??

Remember the definition of an acidic and basic solution is based on the relative amounts of protons in relation to the hydroxides

Title: Re: Question about diluting acidic solution.
Post by: sin0001 on November 11, 2012, 08:59:18 am

pH will approach 7, but won't pass it imo