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supernova1203
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Question 29b)
I have the actual question in the attachment.
I go through the calculations as follows
Mg + O2 ---> MgO
then i balance equation
2Mg + O2----> 2 MgO
since we are given the mass of the magnesium and oxygen reactants, i prooced to finding the number of moles for magnesium and oxygen
for Mg
=2.6/24.3 (Molar mass)
=0.1 mols of Mg
now O2
=1.6/32(Molar mass)
= 0.05 mols
now that we have the number of moles of Mg and O2
i continue and find the limited and excess reactant(although i think both are limited, since there is only enough of Mg and O2 to do the reaction, so I use Mg in cross multiplication with MgO to find the number of MgO moles.
2 mols of Mg ----->2 mols of MgO
0.1 mole ---------> x
2/0.1=2/x
2x=0.2
x=0.1
so now we know the number of moles for MgO is 0.1
finally we calculate the mass of MgO
mass = number of moles x molar mass
molar mass of MgO is 24.3(mg) + 16(Oxygen)
24.3 + 16 = 40.3
mass = 0.1 x 40.3
=4.03 g
according to the law of conservation of mass, both sides reactant and product should be equal and in my calculations they are almost equal, the slight difference (4.2g) on reactants and 4.03g on products side is there because the course curriculum uses different decimal values for molar mass of each element and i use wikipedia (course says Oxygen has molar mass of 16, whereas wikipedia says its 15.9) the same goes for magnesium, book says a value and wikipedia has a slightly different value(again very slightly, which probably accounts for the slight difference in mass)
so the book and i are off by very little, does this check out?
I have the actual question in the attachment.
I go through the calculations as follows
Mg + O2 ---> MgO
then i balance equation
2Mg + O2----> 2 MgO
since we are given the mass of the magnesium and oxygen reactants, i prooced to finding the number of moles for magnesium and oxygen
for Mg
=2.6/24.3 (Molar mass)
=0.1 mols of Mg
now O2
=1.6/32(Molar mass)
= 0.05 mols
now that we have the number of moles of Mg and O2
i continue and find the limited and excess reactant(although i think both are limited, since there is only enough of Mg and O2 to do the reaction, so I use Mg in cross multiplication with MgO to find the number of MgO moles.
2 mols of Mg ----->2 mols of MgO
0.1 mole ---------> x
2/0.1=2/x
2x=0.2
x=0.1
so now we know the number of moles for MgO is 0.1
finally we calculate the mass of MgO
mass = number of moles x molar mass
molar mass of MgO is 24.3(mg) + 16(Oxygen)
24.3 + 16 = 40.3
mass = 0.1 x 40.3
=4.03 g
according to the law of conservation of mass, both sides reactant and product should be equal and in my calculations they are almost equal, the slight difference (4.2g) on reactants and 4.03g on products side is there because the course curriculum uses different decimal values for molar mass of each element and i use wikipedia (course says Oxygen has molar mass of 16, whereas wikipedia says its 15.9) the same goes for magnesium, book says a value and wikipedia has a slightly different value(again very slightly, which probably accounts for the slight difference in mass)
so the book and i are off by very little, does this check out?