Google Answers Logo
View Question
 
Q: Chemistry : Alkali-indicator ( No Answer,   5 Comments )
Question  
Subject: Chemistry : Alkali-indicator
Category: Science > Chemistry
Asked by: santayan-ga
List Price: $2.00
Posted: 16 Jul 2004 03:38 PDT
Expires: 15 Aug 2004 03:38 PDT
Question ID: 374860
Background
Thoughtshop Foundation a non-profit organisation based in Kolkata,
India. We develop educational tools for other developmental
organsiations. For more information please visit
www.thoughtshopfoundation.org.
We are in the process of developing a kit for HIV/AIDS awareness in
schools. The kit comprises games and activities that can be conducted
by teachers or young people themselves.
One of the activities in the kit involves an alkali and an indicator.
The alkali is dissolved in a few transparent cups that participants
are given. The idea is that it is impossible to tell just by looking
which cup has alkaline water.
To ensure ease of use, we are using purified NaOH pellets (produced by
E.Merck India, product ID 17573). In the kit the pellets are
re-packaged into small plastic bottles. Each bottle fills up with
about 20 pellets.

The Problem
The NaOH pellets are delinquescent and they lose shape and get stuck
to each other after about a week even in a bottle sealed with teflon
tape.

·	Is there any inert "coating" that the pellets can be given to reduce
contact with air without significantly affecting the purpose of the
activity?
·	Is there any other way to dry-package small quantities of alkali
(e.g. paper strips, cotton buds)
·	Is there any alternative agent-indicator combination that will meet
our requirements (that is :  can be dry packaged, invisible in water
until indicator is added)


What we have considered
The bottle with pellets could be packed with common salt to minimise
trapped air, and absorb some of the moisture.
We do not know how the salt will react with the pellets over a long period of time.

Thanks for your help!!

Clarification of Question by santayan-ga on 12 Aug 2004 23:55 PDT
We have tried out some of your suggestions, thanks a lot. 
dr_bob-ga K2C03 works, but we got powder, which is cumbersome, trying
to get some more user friendly form. If we find it, it will be the
best alternative so far.
BTW we had reasonable succes by dissolving NaOH in Glycerine. it is
easier to handle. Trying to work out the concentration now.
Answer  
There is no answer at this time.

Comments  
Subject: Re: Chemistry : Alkali-indicator
From: till-ga on 16 Jul 2004 05:33 PDT
 
I realy doubt if you are going to get a comprehensive answer at thhe current
pricing. The question´s topic requires a lot of
research work to be done.
May I point your attention to the google answers pricing guidelines to
find out more ?
Google Answers FAQ:
( http://answers.google.com/answers/faq.html#howmuch )

till-ga
Subject: Re: Chemistry : Alkali-indicator
From: purkinje-ga on 16 Jul 2004 09:14 PDT
 
You might use anhydrous sodium sulfate, which is relatively cheap, and
absorbs water very well. It will not react with the NaOH over time,
and neither will salt. You could also use parafilm to wrap the
container. However, isn't it kind of dangerous to allow kids to be
doing this since putting NaOH into water release tons of heat and
could splash out, etc.?
Subject: Re: Chemistry : Alkali-indicator
From: thelonemonk-ga on 16 Jul 2004 10:26 PDT
 
You may want to try contacting Taylor Industries, a company that makes
all types of water testing kits.  They have a number of alaklinity
reagents and indicators and are generally very helpful in locating
what I need.  You can call them at 800-TEST-KIT.
Subject: Re: Chemistry : Alkali-indicator
From: dr_bob-ga on 16 Jul 2004 14:48 PDT
 
You just need an alkaline solution.

Potassium Carbonate or Sodium Carbonate  (NOT BICARBONATE) are
commercially available and will get you a pH of around 9 ish.  White
powder, not hygroscopic.  Just pick an indicator in that
range(phenolpthalein should work)

chugs,

Bob
Subject: Re: Chemistry : Alkali-indicator
From: djredcat-ga on 12 Aug 2004 06:19 PDT
 
what about using some clear acid (such as a white vinegar?) to add to
water? That way the pH will not go beyond safe levels, and kits can
easily be replicated by teachers wishing to replenish the equipment?

Important Disclaimer: Answers and comments provided on Google Answers are general information, and are not intended to substitute for informed professional medical, psychiatric, psychological, tax, legal, investment, accounting, or other professional advice. Google does not endorse, and expressly disclaims liability for any product, manufacturer, distributor, service or service provider mentioned or any opinion expressed in answers or comments. Please read carefully the Google Answers Terms of Service.

If you feel that you have found inappropriate content, please let us know by emailing us at answers-support@google.com with the question ID listed above. Thank you.
Search Google Answers for
Google Answers  


Google Home - Answers FAQ - Terms of Service - Privacy Policy