Answer:
The concentration the student should write down in her lab is 2.2 mol/L
Explanation:
Atomic mass of the elements are:
Na: 22.989 u
S: 32.065 u
O: 15.999 u
Molar mass of sodium thiosulfate, Na2S2O3 = (2*22.989 + 2*32.065 + 3*15.999) g/mol = 158.105 g/mol.
Mass of Na2S2O3 taken = (19.440 - 2.2) g = 17.240 g.
For mole(s) of Na2S2O3 = (mass taken)/(molar mass)
= (17.240 g)/(158.105 g/mol) = 0.1090 mole.
Volume of the solution = 50.29 mL = (50.29 mL)*(1 L)/(1000 mL)
= 0.05029 L.
To find the molar concentration of the sodium thiosulfate solution prepared we use the formula:
= (moles of sodium thiosulfate)/(volume of solution in L)
= (0.1090 mole)/(0.05029 L)
= 2.1674 mol/L
Potassium chlorate decomposes to form potassium chloride and oxygen.
Balancefd equation is as follows;
2KClO₃ --> 2KCl + 3O₂
stoichiometry of KClO₃ to O₂ is 2:3
At STP, 1 mol of any gas occupies a volume of 22.4 L.
Number of moles in 22.4 L is - 1 mol
Therefore in 11.2 L - 1/22.4 x 11.2 = 0.5 mol
When 3 mol of O₂ are formed - 2 mol of KClO₃ react
therefore when 0.5 mol of O₂ are formed - 2/3 x 0.5 = 0.33 mol of KClO₃ reacted
Therefore 0.33 mol of KClO₃ are required
the mass of KClO₃ required - 0.33 mol x 122.5 g/mol = 40.43 g
Answer: +35
explanation: 30+35£~£
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