18) The balanced chemical equation is given. 2 NaOH (aq) + MgCl 2 (aq) ------> M
ID: 700002 • Letter: 1
Question
18) The balanced chemical equation is given.
2 NaOH (aq) + MgCl2 (aq) ------> Mg(OH)2 (s) + 2 NaCl (aq)
As per the stoichiometric equation,
2 moles NaOH = 1 mole Mg(OH)2.
Molar mass of Mg(OH)2 = (1*24.305 + 2*1.008 + 2*15.9994) g/mol = 58.3198 g/mol.
Mole(s) of Mg(OH)2 corresponding to 0.120 kg = (0.120 kg)*(1000 g/1 kg)*(1 mole/58.3198 g) = 2.0576 mole.
Mole(s) of NaOH required to produce 2.0576 mole Mg(OH)2 = (2.0576 mole Mg(OH)2)*(2 moles NaOH/1 mole Mg(OH)2) = 4.1152 moles.
The volume of the NaOH solution is 200 L; therefore, the molar concentration is (moles of NaOH)/(volume of NaOH) = (4.1152 mole)/(200 L) = 0.020576 mol/L 0.0206 M (ans).
19) The balanced chemical equation for the reaction is
2 NaOH (aq) + H2SO4 (aq) -------> Na2SO4 (aq) + 2 H2O (l)
As per the stoichiometric equation,
2 moles NaOH = 1 mole H2SO4.
Millimoles of H2SO4 = (100 mL)*(0.20 M) = 20.00 mmole.
Millimoles of NaOH required for the titration = (20.00 mmole H2SO4)*(2 moles NaOH/1 mole H2SO4) = 40.00 mmole.
Molarity of NaOH = (mmoles of NaOH)/(volume of NaOH taken) = (40.00 mmole)/(300 mL) = 0.1333 M (ans).
Explanation / Answer
Q18: (5 pts) Calculate molar concentration of a NaOH solution knowing that 200 L of this solution is needed to produce 0.120 kg of Mg(OHals) according to the reaction below 2 NaOH(aq) + MgCl2(aq) Mg(OH)2(s) + 2 Naci(aq) 019: (5 pt) Wat is the molanty of a Naoe souton ir300 mL is needed to neutralize 100 mL of 0.20 M H2SO, solution?
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