# Chemical Forums

## Chemistry Forums for Students => High School Chemistry Forum => Topic started by: mizzyman on December 05, 2011, 12:52:20 PM

Title: AS CHEMISTRY HELP PLEASE!! :(
Post by: mizzyman on December 05, 2011, 12:52:20 PM
Hi am really struggling on some chemistry work i need done and just need some help...
Titrations : A standard solution of Sodium hydroxide containing 1.11g of sold dissolved in a 250cm3 conical flask. 25 cm3 of the alkali was neutralised by 23.2cm3 of nitric acid.

Find - A ) The molarity of the standard solution
B)the moles of alkali used in titration
C) how many moles of nitric acid are present in 23.2 cm3 of solution

Any help with this will be most appreciated...
Title: Re: AS CHEMISTRY HELP PLEASE!! :(
Post by: Arkcon on December 05, 2011, 12:55:40 PM
We start these sort of problems the same way every time ... can you write out a balanced chemical reaction?  It looks like a simple task, but it really is important to visualize what's happening.
Title: Re: AS CHEMISTRY HELP PLEASE!! :(
Post by: mizzyman on December 05, 2011, 01:00:11 PM
Yes of course...a balanced equation for this is :

NaOH + HNO3 ---> NaNO3 + H20
Title: Re: AS CHEMISTRY HELP PLEASE!! :(
Post by: Arkcon on December 05, 2011, 01:34:51 PM
Great.  So ... one mole of NaOH reacts with one mole of HNO3, and they neutralize each other.  But, you have grams and milliliters.  You have to convert.
Title: Re: AS CHEMISTRY HELP PLEASE!! :(
Post by: mizzyman on December 05, 2011, 03:46:54 PM
Ahhh so 0.25L???
Title: Re: AS CHEMISTRY HELP PLEASE!! :(
Post by: UG on December 05, 2011, 06:40:59 PM
Yes the volume of the standard solution is 0.25 L. You have the mass of sodium hydroxide (1.11g), can you work out the number of moles of sodium hydroxide using the mass and molar mass? Once you have figured this out, the molarity of the standard solution can be calculated using the volume.