(Plz answer the following question with further explanation...thz)
1. Why calcium carbonate can be obtained by adding limewater (Ca(OH)2) into the Na2CO3? (I realise hydroxide ion can not react with carbonate ion.)
2. What is the position of sulphite ion and NH3 in the ECS? (I know they are reducing agents...) (Give me a range)
3. One question gives the information that green patches appear on the surface of the metallic surface in a museum.... what metal does the statue contain? The answer is copper... why not iron.... (since I regard Fe forms Fe2+)
4. Which of the following will not react with hot HCl & NaOH?
i. Fe2+
ii. NH4+
iii. SO42-
iv. SO32-
5. If a question regarding neutralization(acid and base), how to determine which reagent should be in excess? (is it based on its solubility in water?)
6. Why mixing dilute HCl can react with sodium sulphite to produce sulphur dioxide. Plz write a chem eq. and name the process
7. Which of the following substances has a sharp b.p.? (wt does sharp b.p. mean)
petrol.... red wine.... molten wax.... liquid ammonia
8. 50 ml of CO2 burns completely in 50 ml of O2. Assuming that all volumes are measured at room temp and pressure, wt is the final gaseous volume of the combustion? (Molar volume of gas: 24dm3)
9. Why using scrubber to remove sulphur dioxide from flue gas in a power station is neutralization? Show an eq
10. An aqueous soln of a compound reacts with dilute HCl to give a gas. This aqueous soln does not give a ppt with NaOH. Wt could it be?
K2SO3..... FeSO4..... (NH4)2CO3
Chem question problem
2010-12-30 4:28 am
回答 (2)
2011-01-01 6:35 am
✔ 最佳答案
10 points for 10 questions... too little. 10 points for further explanation... not possible.
1.
who said that carbonate reacts with hydroxide?
it's the calcium ion reacts with carbonate ion. they form insoluble precipitate.
on the other hand, sodium ion and hydroxide ion remains unreacted, leaving sodium hydroxide solution.
2.
what products and what conditions are you referring to?
acidic / alkaline?
ammonia to what? nitrogen? hydrazine?
sulphite to what? sulphate? dithiolate? or what?
3.
the patch is product of oxidation of metal.
if iron(II) is present, it'll be readily oxidized to iron(III) by air.
instead, it's probably basic copper(II) carbonate, 銅綠. it's the highest oxidized form.
4.
"&" or "OR" ?
iron(II) reacts with hydroxide to give precipitate;
ammonium reacts with hydroxide to give ammonia gas;
sulphite reacts with acid to give sulphur dioxide gas.
5.
excess? why excess? in what reaction?
excess reagent can be determined by mole calculation; but what reaction / experiment you're referring to?
6.
2H(+) + SO3(2-) ------> H2O + SO2
name the process? well, i'd say "displacement", though it's not quite appropriate... or effervescence?
7.
boiling point. boiling points of impure substances are usually ranged, while pure substances' are sharp.
petrol is a mixture of 8-12 carbon-hydrocarbons;
red wine is a mixture of water, ethanol, pigments and flavorings;
wax is a mixture of >18-carbon hydrocarbons.
8.
though CO2 can potentially react with oxygen, it'll NOT burn in oxygen.
what gas are you referring to? methane?
9.
sulphur dioxide dissolves in water to give sulphurous acid, an acid.
it reacts with solution of alkali, like calcium hydroxide. neutralization.
Ca(OH)2 + H2SO3 ------> CaSO3 + 2H2O
10.
both carbonate and sulphite reacts with acid to give gases (carbon dioxide and sulphur dioxide respectively). neither potassium or ammonium precipitates with hydroxide.
if more detailed explanation wanted, open a NEW question and ask for it.
2010-12-30 6:45 am
So many questions wo...
Can u separate them into different parts...
Can u separate them into different parts...
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