MOLECULE
2 answers:
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Answer:
The answer to your question is 0.269 g of Pb
Explanation:
Data
Lead solution = 0.000013 M
Volume = 100 L
mass = 0.269 g
atomic mass Pb = 207.2 g
Chemical reaction
2Pb(s) + O₂(aq) + 4H⁺(aq) → 2H₂O(l) + 2Pb₂⁺(aq)
Process
1.- Calculate the mass of Pb in solution
Formula
Molarity =
Solve for number of moles
Number of moles = Volume x Molarity
Substitution
Number of moles = 100 x 0.000013
Number of moles = 0.0013
2.- Calculate the mass of Pb formed.
207.2 g of Pb ----------------- 1 mol
x g ----------------- 0.0013 moles
x = (0.0013 x 207.2) / 1
x = 0.269 g of Pb
Answer:
827 mL
Explanation:
To answer this question we use the <em>definition of Molarity</em>:
Molarity = mol / L
[Cl⁻] = mol Cl⁻ / L
Now we calculate the moles of Cl⁻ present in 42.0 g of MgCl₂⋅6H₂O:
Molar mass of MgCl₂⋅6H₂O = 24.3 + 2*35.45 + 6*18 = 203.2 g/mol
moles of Cl⁻ = 42.0 g MgCl₂⋅6H₂O ÷ 203.2 g/mol * = 0.4134 mol Cl⁻
Finally we use the definition of molarity to calculate the volume:
0.500 M = 0.4134 mol Cl⁻ / xL
xL = 0.827 L = 827 mL