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Chemistry: Post your doubts here!

Mairaxo

Mairaxo

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soso247 said:
can you help me with mine too please , thank you in advance
Click to expand...
Q4- 1st write the combustion equations of all the alkanes. Then calculate how much volume of O2 is needed and how much is remaining. then add the volume of CO2 produced. For example CH4+2O2-->CO2+2H2O
10cm3 of alkane was used so we take that as 1 mole. 2 moles of O2 were needed so 20cm3 of O2 is used up. 70-20=50cm3 remaining. Then 1 mole of CO2 is produced which means 10cm3 so 50+10=60cm3
do it for the other alkanes :)
 
Mairaxo

Mairaxo

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soso247 said:
can you help me with mine too please , thank you in advance
Click to expand...
Q14- Use the Ar of each elements. Then calculate the mole ratio. For example- Mg(NO3)2 is 5g and 3.29 is lost meaning MgO is 1.71g. moles of Mg(NO3)2= 5/148=0.034 moles. then moles of MgO= 1.71/40=0.043moles. mole ratio should be 1:1 so its not magnesium. try it with calcium and u get it :)
Q25- Just substitute n with any integer and youll get the answer. For example take n=1. then u get C3H6 + 4.5O2--> 3CO2 + 3 H2O so it gets balanced :)
Q37- Its not 2 because 2 will form only one ketone and the other will be an acid. D is the only option with no 2 so chose D :D Also 3 is not possible as both the componds are isomers :)
 
Mairaxo

Mairaxo

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ahmed abdulla said:
>? any one
Click to expand...
i just answered the first one right now : Q4- 1st write the combustion equations of all the alkanes. Then calculate how much volume of O2 is needed and how much is remaining. then add the volume of CO2 produced. For example CH4+2O2-->CO2+2H2O
10cm3 of alkane was used so we take that as 1 mole. 2 moles of O2 were needed so 20cm3 of O2 is used up. 70-20=50cm3 remaining. Then 1 mole of CO2 is produced which means 10cm3 so 50+10=60cm3
do it for the other alkanes :)
 
soso247

soso247

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Mairaxo said:
Q14- Use the Ar of each elements. Then calculate the mole ratio. For example- Mg(NO3)2 is 5g and 3.29 is lost meaning MgO is 1.71g. moles of Mg(NO3)2= 5/148=0.034 moles. then moles of MgO= 1.71/40=0.043moles. mole ratio should be 1:1 so its not magnesium. try it with calcium and u get it :)
Q25- Just substitute n with any integer and youll get the answer. For example take n=1. then u get C3H6 + 4.5O2--> 3CO2 + 3 H2O so it gets balanced :)
Q37- Its not 2 because 2 will form only one ketone and the other will be an acid. D is the only option with no 2 so chose D :D Also 3 is not possible as both the componds are isomers :)
Click to expand...

thank you soo much
 
ahmed abdulla

ahmed abdulla

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Mairaxo said:
Answer is B because more energy is needed when the electron is removed from next orbital. In all options there are 2 p electrons. But in B theres only 1 so the next electron is removed from next orbital so more energy is needed :)
Click to expand...

my godness ... i considered water as a gas :p
Thanks bro .. ;)
what about the last one
 
Tanvir Azad

Tanvir Azad

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Here's a question which i tried but remained unable to solve. So i would really be grateful if anyone attempts to give it a try...
Ques: Two moles of compound P were placed in a vessel. The vessel was heated and compound P
was partly decomposed to produce Q and R. A dynamic equilibrium between chemicals P, Q and
R was established.
At equilibrium x moles of R were present and the total number of moles present was (2 +2/x ).
What is the equation for this equilibrium reaction? [Key: --> is the equilibrium sign]
A P --> 2Q + R
B 2P --> 2Q + R
C 2P --> Q + R
D 2P --> Q + 2R
 
yousef

yousef

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Mairaxo

Mairaxo

Messages
189
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118
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Tanvir Azad said:
Here's a question which i tried but remained unable to solve. So i would really be grateful if anyone attempts to give it a try...
Ques: Two moles of compound P were placed in a vessel. The vessel was heated and compound P
was partly decomposed to produce Q and R. A dynamic equilibrium between chemicals P, Q and
R was established.
At equilibrium x moles of R were present and the total number of moles present was (2 +2/x ).
What is the equation for this equilibrium reaction? [Key: --> is the equilibrium sign]
A P --> 2Q + R
B 2P --> 2Q + R
C 2P --> Q + R
D 2P --> Q + 2R
Click to expand...
ugh this was my exam! i wasnt able to get it that time :/ is it C anyway?
 
Mairaxo

Mairaxo

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Tanvir Azad said:
nope, the answer is D.
Any idea how to solve it?
Click to expand...
okay the only way i get D is by substituting X with the no. of moles of R from the equations. Then find total moles. The equation which has same no. of moles is the right 1 and i got D that way :p
 
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