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Forming alkalis - HSN forum

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Forming alkalis


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#1 jambo david

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Posted 18 January 2006 - 02:01 PM

I can't remember standard grade that well but i thought alkalis were made when a metal oxide is dissolved in water.

Quiestion 2 in past paper 2001 says

Which gas would issolve in water to form an alkali?

A HBr
B NH3
C CO2
D CH4

Answer in B NH3

Can someone explain this please? blink.gif

#2 jambo david

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Posted 18 January 2006 - 02:02 PM

Also does anyone have a site that goes through the past paper questions, explaining the answers? A long shot maybe

#3 dfx

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Posted 18 January 2006 - 06:32 PM

NH base3.gif dissolves in water to form Ammonium Hydroxide NH base4.gif OH which is an alkali.

#4 Nathan

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Posted 18 January 2006 - 07:48 PM

QUOTE(jambo david @ Jan 18 2006, 02:02 PM)
Also does anyone have a site that goes through the past paper questions, explaining the answers? A long shot maybe

View Post



Dont think so....all i can suggest is looking at the SQA Solutions for the last few years...otherwise, just post any questions you have on here and you should get a pretty quick reply

#5 ad absurdum

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Posted 18 January 2006 - 10:06 PM

It takes a H+ from hydronium ions (H30, the ones that make it acidic) and leaves the rest as water molecules, so that increases the ratio of hydroxide ions to hydronium ions.
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#6 Ally

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Posted 18 January 2006 - 10:11 PM

QUOTE(jambo david @ Jan 18 2006, 02:01 PM)
Which gas would issolve in water to form an alkali?

A HBr
B NH3
C CO2
D CH4

Answer in B NH3

View Post


You should be able to cancel two gases straight away - CO2 and CH4. They are non - polar; hence they don't dissolve in water.

And as dfx explained, it's NH3.

#7 ad absurdum

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Posted 19 January 2006 - 04:25 PM

QUOTE(Ally @ Jan 18 2006, 11:11 PM)
You should be able to cancel two gases straight away - CO2 and CH4. They are non - polar; hence they don't dissolve in water.

And as dfx explained, it's NH3.

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Carbon dioxide does dissolve in water, to form H2CO3, but that's acidic though.
But yeah, dfx is right, I think what I said is an additional reason
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#8 Ally

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Posted 20 January 2006 - 06:36 PM

QUOTE(ad absurdum @ Jan 19 2006, 04:25 PM)
QUOTE(Ally @ Jan 18 2006, 11:11 PM)
You should be able to cancel two gases straight away - CO2 and CH4. They are non - polar; hence they don't dissolve in water.

And as dfx explained, it's NH3.

View Post

Carbon dioxide does dissolve in water, to form H2CO3, but that's acidic though.
But yeah, dfx is right, I think what I said is an additional reason

View Post


Oh yeah, so it does. blush.gif





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