Chem qns
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hey!! please help! Tmr chem test and still not know how to do.
Which of the following does not react with dilute sulphuric acid?
A. Magnesium hydroxide
B. Magnesium metal
C. Magnesium nitrate
D. Magensium Oxide
Bi(2)O(3)(s) + 3C(s) --> 2Bi(s) + 3CO(g)
How many moles of carbon are required to remove the oxygen from 2 moles of Bi(2)O(3)?
What is the maximum mass of the element that could be manufactured using thirty-six tonnes of carbon?
Thanks a lo! -
if i am not wrong its C. Magnesium nitrate
second qns should be 6
i'm not sure bout the 3rd qns... sorry -
Hey thanks a lot! it did help me. But would you mind if u explain the qn??
and thanks again. -
Bi(2)O(3)(s) + 3C(s) --> 2Bi(s) + 3CO(g)
36ton-3C
1mol-12ton
12ton x 2 = 24ton if u are asking for Bi. -
hmmm magnesium nitrate is a salt that's why it doesn't react.
Bi(2)O(3)(s) + 3C(s) --> 2Bi(s) + 3CO(g)
in this equation, 1 mole of bi2o3 requires 3 moles of C
thats why 2 moles of it require 6 moles of C
that's what my teacher taught.
sorry if it's wrong
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If I am not wrong OasisBlue's first and second answer is correct while the thrid... I think is 24 tonnes.
3rd Question:
Bi[2]O[3] + 3C --> 2Bi + 3CO
Since 3 moles of Carbon is used in the equation. We may use a direct proportion method.
3 moles C --> 2 moles Bi
36 tonnes C --> 24 tonnes Bi
For the 1st question:
Magnesium Nitrate does not react as it is already a salt[an stable ionic compound].
Magnesium metal, Magnesium oxide and Magnesium oxide do react to form a salt.
For the 2nd question:
Direct proportion method
1 mole of Bi[2]O[3] --> 3 mole C
Therefore,
2mole of Bi[2]O[3] --> 6 mole C
I think the answers are correct though I am not sure... Good Luck... Byebye
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Bi(2)O(3)(s) + 3C(s) --> 2Bi(s) + 3CO(g)
to remove ,in other words is to make it react
since 1 mol of Bi2O3 reacts with 3 mol of C,
2 mol of Bi2O3 should react with 6mols of C. -
Errmm...so what is the ans for the third part ar?..haha..24???...
and anyone got any gut feeling that a certain topic is sure to come out tml? ...haha...other than organic chem -
all wrong explaination for qn 1. Try again.
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first one. answer is C.
cause:
acid + carbonate - Salt + carbon dioxide + water.
acid + metal - salt + hydrogen.
acid + base - salt and water.
I believe metal nitrate is a salt? -
ur explanation confirm right meh?Originally posted by davidche:all wrong explaination for qn 1. Try again.
anyway here's my explanation, not sure whether correct anot
When u mix H2SO4 (aq) with Mg(NO3)2 (aq), the acid does not dissociate its ions (H+ and SO4 2-), therefore they wont "look for and combine with" the Mg2+ and NO3- ions
hope it's correct
cos i anyhow crap 1 -
qns 1
C.
magnesium nitrate is a salt. so if u add sulphuric acid in, its a case of displacement. the hydrogen ion is less reactive than magnesium ion, so theres no way of magnesium being displaced by hydrogen and so there's no reaction.
the other options can react with sulphuric acid because
-magnesium hydroxide(alkali) and magnesium oxide(basic oxide) reacts with sulphuric acid to result in a neutralisation action, ie salt and water are produced.
-magnesium metal will react with sulphuric acid..to form...magnesium sulphate and hydrogen gas if im not wrong o.0
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Sometimes try to answer 'O' level questions in 'A' level way can cause you to lose marks.
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x2!Originally posted by ^tamago^:Sometimes try to answer 'O' level questions in 'A' level way can cause you to lose marks. -
i tot nitrates are soluble?Originally posted by wishboy:ur explanation confirm right meh?
anyway here's my explanation, not sure whether correct anot
When u mix H2SO4 (aq) with Mg(NO3)2 (aq), the acid does not dissociate its ions (H+ and SO4 2-), therefore they wont "look for and combine with" the Mg2+ and NO3- ions
hope it's correct cos i anyhow crap 1 -
dunno lehOriginally posted by davidche:i tot nitrates are soluble?
i tot (aq) means soluble in water nia -
Actually since the nitrates is a MCQ, you are not required to know why this happens for 'O' Levels. Just take it that the rest will react and eliminate them to get Magnesium Nitrate.
Nitrates don't react with H2SO4 but with chloride/iodide/bromide salts.
Reactivity Series for Anions:
I (most reactive)
Br
OH
Cl
NO3
CO3
SO4 (least reactive) -
well my teacher said it's nitrate tooOriginally posted by davidche:i tot nitrates are soluble? -
soluble + soluble = what?Originally posted by OasisBlue:well my teacher said it's nitrate too -
Let me try explaining the first qn.Originally posted by TYING:hey!! please help! Tmr chem test and still not know how to do.
Which of the following does not react with dilute sulphuric acid?
A. Magnesium hydroxide
B. Magnesium metal
C. Magnesium nitrate
D. Magensium Oxide
Bi(2)O(3)(s) + 3C(s) --> 2Bi(s) + 3CO(g)
How many moles of carbon are required to remove the oxygen from 2 moles of Bi(2)O(3)?
What is the maximum mass of the element that could be manufactured using thirty-six tonnes of carbon?
Thanks a lo!
Magnesium nitrate is a soluble salt while magnesium sulphate should be a soluble salt. I am not sure the reason but I guess it has got to do with the balance of ion dipole attraction and id-id attraction.
What I have been taught during my secondary school days are only 3 sulphates are insoluble in water and they are calcium sulphate, lead (II) sulphate and barium sulphate.
Anyway, when sulphuric acid containing hydrogen ions and sulphate ions is added into a solution containing magnesium ions, nitrate ions, hydrogen ions and hydroxide ions, it is merely an addition of ions into the solution. Reason: as stated above.
If barium nitrate is used instead of magnesium nitrate. A visible reaction will occur.
BaSO4 (s) reversible sign Ba2+ + S042-
As concentration of SO4 2- increases, equilibrium will tend to the left for reversible reactions to counteract the change. Therefore, BaS04 (s) will form.