Originally posted by Reynard lee:1) which substance present in car exhaust does not have an effect on limestone?
A)carbon monoxide
B)carbon dioxide
C)nitrogen dioxide
D)sulfur dioxide
( i chose c , which is the answer and why? )
2i) what happens when sodium is burnt in the mixture of gases?
ii)write the chemical equation for the reaction
3)suggest why the air(Argon,nitrogen and oxygen) is filtered before it is compressed.
4) suggest a reason why the gases are stored under high pressure
5) suggest why the percentage composition of the different gases in air is different for the two countries
6) is nuclear power a renewable of non-renewable resource? give a reason for your answer.
7a) decribe, using one suitable example, the formation of ionic bonds between metallic and non-metallic elements.
b)Explain why ionic compounds have high boiling points and most covalent compounds have low boiling point.
8)a volume of 1000dm3 of methane is burnt completely in oxygen.
Calculate the volumes of the gaseous products when measured
i) above 100 degree Celsius
ii) below 100 degree celsius
(assume that all volumes are measured at the same pressure)
thanks!!! and can anyone tell me the indicators and their colours in neutral, acid and alkaline solution? do we need to know all the indicators? our textbook onli wrote colour of indicator when it is in acidic and alkaline solution so i don't know the colour of the neutral solution. thanks a lot!
>>> 1) which substance present in car exhaust does not have an effect on limestone?
A)carbon monoxide
B)carbon dioxide
C)nitrogen dioxide
D)sulfur dioxide
( i chose c , which is the answer and why? ) <<<
CO is non-acidic. It needs to be oxidized to CO2 before it can be hydrolysed to carbonic acid to react with limestone.
>>> 2i) what happens when sodium is burnt in the mixture of gases?
ii)write the chemical equation for the reaction <<<
Sodium, like all reactive metals, much prefer to be in the cationic oxidized state.
>>> 3)suggest why the air (Argon,nitrogen and oxygen) is filtered before it is compressed.
4) suggest a reason why the gases are stored under high pressure <<<
Make your own reasonable deductions : http://en.wikipedia.org/wiki/Compressed_air
>>> 5) suggest why the percentage composition of the different gases in air is different for the two countries <<<
Good question with interfaces chemistry with geography, economics and industrial sciences. Think about the sources (eg. industrial) of various gases and how they might be vary significantly across countries and continents (eg. highly industrialized versus non-inhabited). Also, Google-&-Wikipedia is excellent for learning and research.
>>> 6) is nuclear power a renewable of non-renewable resource? give a reason for your answer. <<<
Like any General Paper question, this is debatable (there isn't a simple yes or no answer for this one), and groups with vested interests on either side will push for their own agenda. Google "nuclear power renewable"
>>> 7a) decribe, using one suitable example, the formation of ionic bonds between metallic and non-metallic elements.
b)Explain why ionic compounds have high boiling points and most covalent compounds have low boiling point. <<<
Metal atom loses electron(s) to form cation. Non metal atom gains electron(s) to form anion. Electrostatic attraction between oppositely charged ions are referred to as 'ionic bonds'. These electrostatic attractions between ions are significantly stronger than the relatively weaker intermolecular (van der Waals) attractions between molecules of covalent compounds.
>>> 8)a volume of 1000dm3 of methane is burnt completely in oxygen.
Calculate the volumes of the gaseous products when measured
i) above 100 degree Celsius
ii) below 100 degree celsius
(assume that all volumes are measured at the same pressure) <<<
Apply PV=nRT formula. Question is incomplete with specific values for specific parameters (eg. 1000dm3 at r.t.p or s.t.p?), so use algebraic variables and leave them in the answer as necessary.
>>> thanks!!! and can anyone tell me the indicators and their colours in neutral, acid and alkaline solution? do we need to know all the indicators? our textbook onli wrote colour of indicator when it is in acidic and alkaline solution so i don't know the colour of the neutral solution. thanks a lot! <<<
Google by thy Sword, Wikipedia be thy Shield.
http://en.wikipedia.org/wiki/PH_indicator
The colour of any indicator in neutral solution depends on which pH (acidic or alkaline environment) you began with, and which direction you're going with the titration.
chim
i dun understand.. these are o level questions and must of the things u say are not in the syllabus
thank you very much for answering :D
What does the alphabets in PV=nRT represent? Is it tested in O level?
Originally posted by qdtimes2:What does the alphabets in PV=nRT represent? Is it tested in O level?
It's part of the 'A' level syllabus.
If it is included in an 'O' level exam qn, the formula will be provided with explanations. Do you recall how the molar volume of any gas at r.t.p is said to be 24dm3? It's actually based on this formula :
P V = n R T
(1atm) (Vdm3) = (1mol) (0.08206) (298K)
V = 24.45388dm3 = 24dm3 (to 2 significant figures)
Originally posted by UltimaOnline:
It's part of the 'A' level syllabus.
If it is included in an 'O' level exam qn, the formula will be provided with explanations. Do you recall how the molar volume of any gas at r.t.p is said to be 24dm3? It's actually based on this formula :
P V = n R T
(1atm) (Vdm3) = (1mol) (0.08206) (298K)
V = 24.45388dm3 = 24dm3 (to 2 significant figures)
is it releated to Boyle, Gay-Lussac laws
Originally posted by SBS n SMRT:is it releated to Boyle, Gay-Lussac laws
Yes, the formula PV=nRT is the combination of Boyle's, Charles', Gay-Lussac's, and Avogadro's Laws :
Originally posted by UltimaOnline:
Yes, the formula PV=nRT is the combination of Boyle's, Charles', Gay-Lussac's, and Avogadro's Laws :
no wonder i find the formulae familar yet distant..........i learned all but have not taughted the link