Answer:
E) Two of the above statements are true.
Explanation:
The options are:
A) Before the solution is titrated with HCl it is pink and when the color changes from pink to colorless, the moles of H*(aq) equals the moles of OH"(aq) used in the hydrolysis of the neutralized aspirin. <em>TRUE. </em>Before the solution is titrated, there is an excess of NaOH (Basic solution, phenolphtalein is pink). Then, at equivalence point, after the addition of HCl, the pH is acidic and phenolphtalein is colorless.
B) Before the solution is titrated with HCl it is colorless and when the color changes from colorless to pink, the moles of H*(aq) equals the excess moles of OH(aq) added. <em>FALSE. </em>As was explained, before the titration, the solution is pink.
C) 25.0 mL of 0.100 M NaOH was added to the sample to hydrolyze the neutralized aspirin in the solution. The titration with HCl allows us to determine the moles of excess OH(aq) added. Once we determine the moles of excess OH(aq), we can determine moles of OH"(aq) used in the hydrolysis of the neutralized aspirin, which is equal to the moles of aspirin in the recrystallized aspirin. <em>TRUE. </em>Aspirin requires an excess of base (NaOH) for a complete dissolution (Hydrolysis). Then, we add H+ as HCl to know the excess moles of OH-. As we know the added moles of OH-, we can find the moles of OH that reacted = Moles of aspirin.
D) We can determine the moles of aspirin in the recrystallized aspirin by titrating with the 0.100 M NaOH to the neutralization point. The purpose of the hydrolysis of the neutralized aspirin and the back-titration with the 0.100 M HCl is to confirm the moles of aspirin in the recrystallized aspirin. <em>FALSE. </em>NaOH can be added directly unyil neutralization point because, initially, aspirin can't be dissolved completely
E) Two of the above statements are true. <em>TRUE</em>
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Right option is:
<h3>E) Two of the above statements are true.</h3>
Answer is: A) The solution turns blue litmus to red.
Sulfuric acid (H₂SO₄) is a strong acid, it means that the solution of sufuric acid is more acidic (pH<7) than water (pH = 7).
Chemical dissociation of sulfuric acid in water:
H₂SO₄(aq) → 2H⁺(aq) + SO₄²⁻(aq).
When solution turns phenolphthalein pink, it means it is basic (pH>7).
Sulfuric acid has more hydrogen ions (H⁺) and less hydroxide ions (OH⁻) than water.
Answer:
After increasing the volume, we have 1.81 moles of hydrogen gas in the container
Explanation:
Step 1: Data given
Number of moles hydrogen gas (H2) = 1.24 moles
Volume of hydrogen gas (H2° = 27.8 L
The final volume is increas to 40.6 L
Step 2: Calculate the new number of moles
V1/n1 = V2/n2
⇒with V1 = the initial volume = 27.8 L
⇒with n1 = the initial number of moles H2 = 1.24 moles
⇒with V2 = the final volume = 40.6 L
⇒with n2 = the new number of moles = TO BE DETERMINED
27.8L / 1.24 moles = 40.6 L / n2
n2 = 40.6 / (27.8/1.24)
n2= 1.81 moles
After increasing the volume, we have 1.81 moles of hydrogen gas in the container
Answer:
The volume of the potassium hydroxide solution was 164.1 mL
Explanation:
In the equivalence point of a titration between an acid an a base, the moles of H⁺ are equal to the moles of OH⁻.
In the case of potassium hydroxide (KOH) and hydrochloric acid (HCl), an equation that represents the equivalence point would be:
Using that equation and the data given in the problem, we can calculate the volume of potassium hydroxide:
