(a) when 5g of calcium is burnt in 2g of oxygen then 7g of calcium oxide is produced. what mass of calcium oxide will be produced when 5g of calcium is burnt in 20g of oxygen .which law of chemical combination will govern your answer? state the law. (b) write the chemical formula of calcium oxide.
Answers
Answered by
89
The reaction between oxygen and calcium is as follows:
2Ca + O₂ -----------------> 2CaO
The mole ratio of the above equation is :
2:1:2 which means that every 2 moles of calcium requires 1 mole of oxygen to form 2 moles of calcium oxide.
Calculate the actual moles of both oxygen and calcium to find the limiting reagent in the equation as follows;
moles of oxygen :
moles = mass/molar mass -----> 2/32 = 0.0625 moles
moles of calcium:
moles = mass/molar mass ---------> 5/40 = 0.25 moles
When 20 grams of oxygen is used:
find moles of 20g of oxygen
moles = mass/molar mass -----------> 20/32 = 0.625 moles
Therefore calcium is the limiting reagent --we will use its actual moles(which is 0.25) to calculate the mass of CaO produced.
The mole ratio between Ca used and CaO produced from the equation above is: 2:2 which is 1 to 1. This means that 1 mole of Ca will give 1 mole of CaO.
Since the mole of Ca is 0.125, then mole of CaO produced will also be 0.125.
If the moles of CaO produced is 0.125, calculate its mass as follows:
Mass = moles × molar mass
molar mass of CaO is 56
Therefore mass produced = 0.125 × 56
= 7g
a) The mass of calcium oxide produced will be 7g(all the calcium will be used up but the oxygen will remain in excess)
b) The law of chemical combination governing this equation is the law of reciprocal proportions (and the law of conservation of mass as well)
c) The chemical formula of Calcium oxide is CaO
2Ca + O₂ -----------------> 2CaO
The mole ratio of the above equation is :
2:1:2 which means that every 2 moles of calcium requires 1 mole of oxygen to form 2 moles of calcium oxide.
Calculate the actual moles of both oxygen and calcium to find the limiting reagent in the equation as follows;
moles of oxygen :
moles = mass/molar mass -----> 2/32 = 0.0625 moles
moles of calcium:
moles = mass/molar mass ---------> 5/40 = 0.25 moles
When 20 grams of oxygen is used:
find moles of 20g of oxygen
moles = mass/molar mass -----------> 20/32 = 0.625 moles
Therefore calcium is the limiting reagent --we will use its actual moles(which is 0.25) to calculate the mass of CaO produced.
The mole ratio between Ca used and CaO produced from the equation above is: 2:2 which is 1 to 1. This means that 1 mole of Ca will give 1 mole of CaO.
Since the mole of Ca is 0.125, then mole of CaO produced will also be 0.125.
If the moles of CaO produced is 0.125, calculate its mass as follows:
Mass = moles × molar mass
molar mass of CaO is 56
Therefore mass produced = 0.125 × 56
= 7g
a) The mass of calcium oxide produced will be 7g(all the calcium will be used up but the oxygen will remain in excess)
b) The law of chemical combination governing this equation is the law of reciprocal proportions (and the law of conservation of mass as well)
c) The chemical formula of Calcium oxide is CaO
Answered by
50
When Calcium is burnt in Oxygen the following reaction takes place.
2Ca + O₂ → 2CaO
Answer(a). From the reaction it is clear that 2 moles of calcium reacts with 1 mole of oxygen to give 2 moles of CaO. So the mole ratio is 2:1:2.
Now it is given that 5 g of Ca reacts with 2 g of oxygen to give 7 g of CaO.
N.O of moles of Ca = 5/40 = .125
N.O of moles of O₂ = 2/32 = .0625
here O₂ is limiting reactant and will disappear first and since 1 mole of O₂ forms 2 moles of CaO ,therefore .0625 moles of O₂ will form .125 moles of CaO and it is given tha 7 g of Cao is formed.
In the second case 20 g of O₂ i.e .625 moles of O₂ is used and hence Ca is the limiting reactant which is present 5g i.e .125 moles and as it's given that 2 moles of Ca forms 2 moles of CaO ,therefore 0.125 moles of Ca will form 0.125 moles of CaO.
So mass of CaO produced = 0.125*56 = 7g
The law of Chemical combination that governs this is "Law of Conservation of Mass". According to this law mass of product in a chemical reaction is equal to the mass of reactants.
Answer(b). Chemical Formula of Calcium Oxide is CaO.
2Ca + O₂ → 2CaO
Answer(a). From the reaction it is clear that 2 moles of calcium reacts with 1 mole of oxygen to give 2 moles of CaO. So the mole ratio is 2:1:2.
Now it is given that 5 g of Ca reacts with 2 g of oxygen to give 7 g of CaO.
N.O of moles of Ca = 5/40 = .125
N.O of moles of O₂ = 2/32 = .0625
here O₂ is limiting reactant and will disappear first and since 1 mole of O₂ forms 2 moles of CaO ,therefore .0625 moles of O₂ will form .125 moles of CaO and it is given tha 7 g of Cao is formed.
In the second case 20 g of O₂ i.e .625 moles of O₂ is used and hence Ca is the limiting reactant which is present 5g i.e .125 moles and as it's given that 2 moles of Ca forms 2 moles of CaO ,therefore 0.125 moles of Ca will form 0.125 moles of CaO.
So mass of CaO produced = 0.125*56 = 7g
The law of Chemical combination that governs this is "Law of Conservation of Mass". According to this law mass of product in a chemical reaction is equal to the mass of reactants.
Answer(b). Chemical Formula of Calcium Oxide is CaO.
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