HELPPP!!
The thermal decomposition of potassium chlorate is a convenient preparation for small amounts of oxygen gas in the laboratory. The reaction is:
2KClO3(s) -> 2KCl(s) + 3O2(g)
What mass of potassium chlorate would produce a theoretical yield of 10.00 g of oxygen?
a) 25.5 g b) 30.4 g c) 38.3 g d) 51.1 g e) 57.5 g
Im trying to teach myself chemistry and this question has popped up and i have no idea how to answer it and what the question is actually asking? and i cant find any explanation in my notes etc.
Could you please tell me the answer, how you got to the answer, and just explain the basic concepts of the question.
Thanks. you will be my lifesaver!
The thermal decomposition of potassium chlorate is a convenient preparation for small amounts of oxygen gas in the laboratory. The reaction is:
2KClO3(s) -> 2KCl(s) + 3O2(g)
What mass of potassium chlorate would produce a theoretical yield of 10.00 g of oxygen?
a) 25.5 g b) 30.4 g c) 38.3 g d) 51.1 g e) 57.5 g
Im trying to teach myself chemistry and this question has popped up and i have no idea how to answer it and what the question is actually asking? and i cant find any explanation in my notes etc.
Could you please tell me the answer, how you got to the answer, and just explain the basic concepts of the question.
Thanks. you will be my lifesaver!
-
Easy. 10 grams of oxygen equals .625 moles oxygen. Since 2 parts KClO3 are required to make 3 parts of O2, we know that 2/3 as many moles of KClO3 are required.
2/3 times .625 = .416666667 moles KClO3.
molar mass KClO3 is 122.55 g/mol. (.41666667 moles)(122.5 g/mol) = 51.1 grams KClO3.
D) 51.1
If I helped, rate this the best answer. If you need clarification, just ask!
2/3 times .625 = .416666667 moles KClO3.
molar mass KClO3 is 122.55 g/mol. (.41666667 moles)(122.5 g/mol) = 51.1 grams KClO3.
D) 51.1
If I helped, rate this the best answer. If you need clarification, just ask!
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Well , its quite an easy question ...but the problem is u dont know the basic concepts ....
This question is based on mole concept and stoichimetry calculations ....
1st method .... (POAC Method )
U dont need to balance chemical equation for this method .......so
writing the chemical eq as
KClO3(s) ->KCl(s) + O2(g)
Now it says that number of atoms of oxygen on both r equal ....( lass of conservation of mass )
Since kclo3 contains 3 atoms of O and o2 contains 2 atoms
=> 3xatoms of O in kclo3 = 2 x atoms of O in O2
3x Moles of kclo3 = 2 x moles of O2
also molecular mass of kclo3 = 122.6 and molecular mass of 02 = 32
mole = w ( mass given ) / molecular mass
=> 3 X( w /122.6 ) = 2 x ( 10 / 32 )
w = 25.54 gms
( NOTE : 10 gms of oxygen means 10 gms of O2 and not O bcoz it doesnt exist as O )
2nd method ...stoichiometry method
it requires balancing of equations ....
here it is balanced .....
2KClO3(s) -> 2KCl(s) + 3O2(g)
Now it says tht
ratio of moles of substances = ratio of their coefficients
here coefiicient of kclo3 = 2 and 02 = 3
=> moles of kclo3 / moles of 02 = 2/3
thus we get same result from both methods ......
i personally recommend using 1st method as it doesnt require balancing ......
HOpe tht helps !! Also buy some decent book on mole concept !! Good Luck !!
This question is based on mole concept and stoichimetry calculations ....
1st method .... (POAC Method )
U dont need to balance chemical equation for this method .......so
writing the chemical eq as
KClO3(s) ->KCl(s) + O2(g)
Now it says that number of atoms of oxygen on both r equal ....( lass of conservation of mass )
Since kclo3 contains 3 atoms of O and o2 contains 2 atoms
=> 3xatoms of O in kclo3 = 2 x atoms of O in O2
3x Moles of kclo3 = 2 x moles of O2
also molecular mass of kclo3 = 122.6 and molecular mass of 02 = 32
mole = w ( mass given ) / molecular mass
=> 3 X( w /122.6 ) = 2 x ( 10 / 32 )
w = 25.54 gms
( NOTE : 10 gms of oxygen means 10 gms of O2 and not O bcoz it doesnt exist as O )
2nd method ...stoichiometry method
it requires balancing of equations ....
here it is balanced .....
2KClO3(s) -> 2KCl(s) + 3O2(g)
Now it says tht
ratio of moles of substances = ratio of their coefficients
here coefiicient of kclo3 = 2 and 02 = 3
=> moles of kclo3 / moles of 02 = 2/3
thus we get same result from both methods ......
i personally recommend using 1st method as it doesnt require balancing ......
HOpe tht helps !! Also buy some decent book on mole concept !! Good Luck !!