Discuss the questions here!

For Science Chemistry

Paper 5152/03 and 5154/03

open already ah? I was thinking how strange for a mod to lock his own thread after the opening post

grrr GG liao.

ammonia + water -> aqueous ammonia
the equation i dunnoe how to write.

simi oxygen welding...oso dunnoe.

hydrogen chloride dissolves in water, equation oso dunnoe

Originally posted by Y_Shun:

grrr GG liao.

ammonia + water -> aqueous ammonia
the equation i dunnoe how to write.

simi oxygen welding...oso dunnoe.

hydrogen chloride dissolves in water, equation oso dunnoe

NH3(g) + H2O(l) --> NH4OH(aq)

Hydrogen Chloride dissolves in water to gives Hydrochloric acid.

i din know aqeous ammonia is NH4(OH)... !!!!!!!!!!!!!!

wasted =[

all those weid werid qtns come out wf.

ya loh.. sian liao lah… alot of question come out on topic : metals .. i only study reactivity series and burst furnace on that topic only….. siao liao la… no more As for me

Share some of the questions which you don't know. We can help you figure out.

careless.

btw, the school never return us A MATH PAPAER 2

Originally posted by Y_Shun:

careless.

btw, the school never return us A MATH PAPAER 2

You must request from the Chief Presidenting Examiner.

OKay this time round, the chemicals seem to be all colourless. I remember during my O level chem practical, i just need to observe what color/gas other pple are getting, then i analyse the questions and plus my chemicals...i know the answer liao

Originally posted by Darkness_hacker99:

You must request from the Chief Presidenting Examiner.

lol who is that?

dunno rah....they say can get it frm school office. we go get they say haven't 24 hrs blah blha blha...then nobody care liao.

Lame la..most of the topics that came out i never study properly or never study at all..

wooooooooooot

marcromolcules my death chapter neva come out...MCQ coming out for sure

Wah riaos. Pwned hard hard.

This paper more of thinking required.

GG.

LAST QTN.

It ask whats the reactions rubidium with water.

Do we just say cold water? or oso with steam

Originally posted by Y_Shun:

LAST QTN.

It ask whats the reactions rubidium with water.

Do we just say cold water? or oso with steam

Take it as cold water, unless it specify steam.

2Rb(s) + 2H2O(l) --> 2RbOH(aq) + H2(g)

Originally posted by Darkness_hacker99:

Hydrogen Chloride dissolves in water to gives Hydrochloric acid.

I wrote:
HCl + H2O --> H2O2 + Cl2 + H2

I balanced in test paper. But not gona balanced here.

I wiki-ed, H2O2, hydrogen peroxide is weak acid. Cl2, to the right of the periodic table, also acid. I think. Not sure.

Originally posted by zanemiller:

I wrote:
HCl + H2O --> H2O2 + Cl2 + H2

I balanced in test paper. But not gona balanced here.

I wiki-ed, H2O2, hydrogen peroxide is weak acid. Cl2, to the right of the periodic table, also acid. I think. Not sure.

you wiki liao....still dunno the answer? H2O2 not so easily produced.

HCl is very soluble in water (and in other polar solvents).

Upon contact, H2O and HCl combine to form hydronium cations H3O+ and chloride anions Cl- through a reversible chemical reaction:

HCl + H2O ¨ H3O+ + Cl−

http://en.wikipedia.org/wiki/Hydrogen_chloride

Originally posted by zanemiller:

I wrote:
HCl + H2O --> H2O2 + Cl2 + H2

I balanced in test paper. But not gona balanced here.

I wiki-ed, H2O2, hydrogen peroxide is weak acid. Cl2, to the right of the periodic table, also acid. I think. Not sure.

Firstly, I don't think that HCl + H2O will produce Hydrogen Peroxide. Cl2 is Chlorine gas, which is found at group VII of the periodic table.

I still believe that the product is Hydrochloric acid.

As for why is the solution acidic, the correct answer I supposed. is because of the presence of Hydrogen ion.

The front statement "...to form an acidic solution..." acts as a smokescreen, but it's actually testing you on the knowledge of what gives acids it's property.

For this case, it's because of the Hydrogen ions.

Originally posted by HyuugaNeji:

you wiki liao....still dunno the answer? H2O2 not so easily produced.

HCl is very soluble in water (and in other polar solvents).

Upon contact, H2O and HCl combine to form hydronium cations H3O+ and chloride anions Cl- through a reversible chemical reaction:

HCl + H2O ¨ H3O+ + Cl−

http://en.wikipedia.org/wiki/Hydrogen_chloride

Hydronium cation H3O+ is not under O level syllabus.

Originally posted by Y_Shun:

i din know aqeous ammonia is NH4(OH)... !!!!!!!!!!!!!!

wasted =[

all those weid werid qtns come out wf.

NH4(OH) <-- No need bracket.

Originally posted by Darkness_hacker99:

Take it as cold water, unless it specify steam.

2Rb(s) + 2H2O(l) --> 2RbOH(aq) + H2(g)

lucky they never say want equations...if not i gg.

but i only say it produces rubidium hydroxide....

hmm then i wrote the reaction with oxide incase.

Originally posted by zanemiller:

I wrote:
HCl + H2O --> H2O2 + Cl2 + H2

I balanced in test paper. But not gona balanced here.

I wiki-ed, H2O2, hydrogen peroxide is weak acid. Cl2, to the right of the periodic table, also acid. I think. Not sure.

H2O2 is a lewis acid but HCl is a strong Bronsted acid.
In your question, it is assumed that the term acid refers to Bronsted acid.

You think too much... too complicated

so how? I not really sure how well I did. Haisss… I just hope that 70%+ gurantee A2. Anyone who has friends who did very well?

me took the paper too.

lost much marks on mole question, and the hydrogen chloride question too.

and i wrote ammonia + water -> ammonium hydroxide

why molten state ionic compound can conduct electricity?

i wanted to write the txtbk says so, but dint lah made a wild guess that electricity can pass through the spaces the ions have between them..

haiz, section B was rather easy though