chem help

[hassam]

Which salt is produced by adding aqueous ammonia to aqueous sulphur dioxide until just
alkaline?
A NH4 SO3 B NH4 SO4 C (NH4)2 SO3 D (NH4)2 SO4

 

[hassam]

8 Which of the following would be suitable for use in a fire extinguisher?
1 CBrF3
2 CH3(CH2)5CH2Br
3 HCl

 

[libra94]

Which salt is produced by adding aqueous ammonia to aqueous sulphur dioxide until just
alkaline?
A NH4 SO3 B NH4 SO4 C (NH4)2 SO3 D (NH4)2 SO4

C...when SO2 is added we get SO3 in the salt and when SO3 is added we get SO4 in the final salt
the valency for SO3 is -2 and the valency for NH4 is +1 so we cross the numbers and get (NH4)2SO3.

 

[libra94]

8 Which of the following would be suitable for use in a fire extinguisher?
1 CBrF3
2 CH3(CH2)5CH2Br
3 HCl

 

[ahmed t]

for question 8 i would say b or d
u cant use an acid as a fire extinguisher
and im not sure about the second option but i dont think its correct because hydrocarbons are flamable
so i would go for D

 

[DragonCub]

Which salt is produced by adding aqueous ammonia to aqueous sulphur dioxide until just
alkaline?
A NH4 SO3 B NH4 SO4 C (NH4)2 SO3 D (NH4)2 SO4

C...when SO2 is added we get SO3 in the salt and when SO3 is added we get SO4 in the final salt
the valency for SO3 is -2 and the valency for NH4 is +1 so we cross the numbers and get (NH4)2SO3.

Well I think the key point in this question is about the OXIDATION STATE/NUMBER. It is clear that before and after the reaction, the oxidation state is unchanged for N, H and O. So that of S shouldn't change (i.e. remains at +4). So only in SO3 ion S has +4 oxidation state. Answer is C therefore.

 

[hassam]

oh ....i remember ...dragon club u r ryt....cos its a neutralisation reaction and NEUTRALISATION reactions are not redox reactions

 

[hassam]

oh ....i remember ...dragon club u r ryt....cos its a neutralisation reaction and NEUTRALISATION reactions are not redox reactions

 

[hassam]

well question 8 abt fire extinguishers....ahmed t ur anser is ryt bt still nt convincing explanation for me

 

[hassam]

"Halogenoalkanes in which all of the hydrogen atoms in the alkane have been replaced by halogen atoms are difficult to burn - hence their use in flame retardants and even in fire extinguishers."....this what chemguide says.....so u r ryt abt that flammability thing in 2 thnxxx

 

[nehaoscar]

"Halogenoalkanes in which all of the hydrogen atoms in the alkane have been replaced by halogen atoms are difficult to burn - hence their use in flame retardants and even in fire extinguishers."....this what chemguide says.....so u r ryt abt that flammability thing in 2 thnxxx

Which revision guide do you use?

 

[alevel_student]

I need HALOGENOALKANES past paper questions can u help me out pls ......