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Chemistry: Post your doubts here!

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When ever two stages are involved in reaction its ethalpy profile diagram will have two humps in its graph .......as it is stated in the question X-Y is positive thus it will be endo and reactants will have low energy than the products....in Y-Z ethalpy change is neg thus its exo and reactants will have high energy than products as shown in option A
So it can't be B r8
 
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Screenshot_20171231_004730_2.png
 
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2Al+Ba(NO3)2--->Al2O3+Bao+N2
Mole of Ba(NO3)2= 0.783/(261)=3x10^-3 mole
Mole of N2=mole of Ba(NO3)2= 3x10^-3 mole
1 mole--->24 dm^3
3x10^-3= 24x(3x10^-3)=0.072 dm^3
0.072dm^3=72 cm^3.
the answer is B. right?

The balanced equation should be 10Al + 3Ba(NO3)2 = 5Al2O3 + 3BaO + 3N2 , right? therefore we will get a different answer..
plz reply as soon as possible..
 
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Can anyone help me please?
What is involved in the mechanism of the mechanism of the reaction between aqueous sodium hydroxide and 2-bromo-2-methylbutane?
A heterolytic bond fission, attack by an electrophile on a carbanion
B heterolytic bond fission, attack by an nucleophile on a carbocation
C homolytic bond fission, attack by an electrophile on a carbanion
D homolytic bond fission, attack by an nucleophile on a carbocation
 
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Can anyone help me please?
What is involved in the mechanism of the mechanism of the reaction between aqueous sodium hydroxide and 2-bromo-2-methylbutane?
A heterolytic bond fission, attack by an electrophile on a carbanion
B heterolytic bond fission, attack by an nucleophile on a carbocation
C homolytic bond fission, attack by an electrophile on a carbanion
D homolytic bond fission, attack by an nucleophile on a carbocation

2-bromo-2-methylbutane is a tertiary halogenoalkane and will undergo sN1 'unimolecular' via carbocation reactions.



The C-Br bond will be broken heterolytically and a carbocation ion will be formed. The carbocation would then be attacked by the nucleophile (OH-)
 
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The balanced equation should be 10Al + 3Ba(NO3)2 = 5Al2O3 + 3BaO + 3N2 , right? therefore we will get a different answer..
plz reply as soon as possible..

I don't have the context of the full question.

But in both equations, the ratio of Ba(NO3)2 and N2 happens to be 1:1. Therefore, it's a coincidence that the answers ended up to be the same.
 
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Hey download this app called A level chemistry by overdose
available on playstore
 

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lime stone is CaCO3
lime is CaO or Ca(OH)2
now all three would react with acids because acids react with carbonates (CaCO3) and bases (CaO/Ca(OH)2)

But old lime mortar effervesces (which means produces a gas), so this would be CaCO3 as it would produce CO2 gas with HCl

between A and D, D would be correct as water is present as well so quiklime would be Ca(OH)2
 
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Hi Everyone I would like to post some very inportant notes for cie AS Level Chemistry. Download the notepad file. It contains the link to the website for Chemistry notes AS Levels only
 

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View attachment 62955
why ans is B plzzzzzzzzzz help

First, you write out the equation

2C3H7OH(l) + 9O2(g) -> 6CO2(g) + 8H2O(l)

0.1 mol of propanol = 2.4dm3

From the equation:
2mol of propanol reacts with 9mol of oxygen
0.1mol of propanol reacts with 0.45mol of oxygen

0.45mol of oxygen=10.8dm3

After the reaction,
Since we have 12dm3 of oxygen (excess), there will be 1.2dm3 of oxygen left.
7.2dm3 of carbon dioxide will be produced from the reaction.

1.2+7.2=8.4dm3
 
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