Answer: B) You are to continue heating the round-bottom flask until all liquid has been distilled.
Explanation:
Fractional distillation refers to a method that's useful for the separation of mixtures of solvents whereby there is less than 40°C in the boiling point difference.
With regards to the options given, the incorrect statement about the procedure for distillation is that you are to continue heating the round-bottom flask until all liquid has been distilled. This isn't correct.
D. Steam enters a cylinder and pushes a piston
Answer:
pH of resulting solution = 7.98
Explanation:
The balanced equation
HA + NaOH - Na+ + A- + H2O
Number of moles of A = Number of moles of HA = Number of moles of NaOH
= 35.8/1000 * 0.020 = 0.000716 mol
Initial concentration of A = 0.000716/0.0608 = 0.01178 M
pKb = 14 – pKa = 14 -3.9 = 10.1
Kb = 10^{-Kb} = 10^{-10.1} = 7.943 * 10^-11
Kb = [HA][OH-]/[A-]
Kb = a^2/(0.01178 -a) = 7.943 * 10^-11
a^2 + 7.943 * 10^-11 a – 9.357 * 10^-13 = 0
a = 9.673 * 10^-7
OH- = a = 9.673 * 10^-7 M
pOH = -log [OH-] = -log (9.673 * 10^-7) = 6.02
pH = 14-6.02 = 7.98
Answer:
The correct answer is 0.52 moles.
Explanation:
Based on the given question, 37 grams of magnesium reacts with 38 grams of HCl to produce MgCl2 or magnesium chloride. The reaction is:
Mg (s) + 2HCl (aq) ⇒ MgCl2 (aq) + H2 (g)
There is a need to find the theoretical yield in moles of MgCl2. The formula for calculating the no. or moles is mass/molar mass. Therefore, moles of magnesium is 37/24 = 1.54 and moles of HCl will be 38/36.5 = 1.04.
From the reaction it is clear that one mole of magnesium reacts with two moles of HCl, as lesser quantity of HCl is present in the given case, therefore, HCl will be the limiting reagent.
Now theoretical moles of magnesium chloride will be,
= moles of HCl / 2
= 1.04 / 2
= 0.52 moles
