Select all the correct answers.

Calculate the theoretical yield of aspirin obtained when 2.0 g of salicylic acid and 5.0 mL of acetic anhydride (density = 1.08

blondinia [14]

Answer:

The % yield = 61.3 %

The aspirin is impure, since the melting point was too low

Explanation:

Step 1: Data given

Mass of salicylic acid = 2.0 grams

Volume of acetic anhydride = 5.0 mL ( Density = 1.08 g/mL)

Molar mass of acetic anhydride =102.1 g/mol

Molar mass of salicylic acid = 138.2 g/mol

Step 2: The balanced equation

C7H6O3 + C4H6O3 → C9H8O4 + CH3COOH

Step 3: Calculate moles of salicylic acid

Moles salicylic acid = mass salicylic acid / Molar mass salicylic acid

Moles salicylic acid = 2.0 grams /138.2 g/mol

Moles salicylic acid = 0.0145 moles

Step 4: Calculate moles of acetic anhydride

Mass of acetic anhydride = 1.08 g/mL * 5.0 mL = 5.4 grams

Moles acetic anhydride = 5.4 grams / 102.1 g/mol

Moles acetic anhydride = 0.0529 moles

Step 5: Calculate limting reactant

Mole ratio is 1:1 so since salicylic acid has the smallest number of moles, it's the limiting reactant

Salicylic acid will completely be consumed (0.0145 moles)

Acetic anhydride is in excess. There will 0.0145 moles be consumed.

There will remain 0.0529 -0.0145 = 0.0384 moles of acetic anhydride

Step 6: Calculate moles of aspirin

Since mole ratio is 1:1 there will be produced 0.0145 moles of aspirin

Step 7: Calculate mass of aspirin

Mass of aspirin = 0.0145 moles * 180.158 g/mol

Mass of aspirin = 2.61 grams = theoretical yield

Step 8: Calculate % yield

% yield = actual yield / theoretical yield

% yield = (1.6 grams / 2.61 grams)*100%

% yield = 61.3 %

Since the melting point of pure aspirin is 138-140, this means that the aspirin was impure. It's possible that the aspirin still has insoluble impurities in it.

8 0

3 years ago

Write an equation showing how this buffer neutralizes added base (csoh).

kakasveta [241]

Here, the buffer is NH₄Cl + NH₃
The strong base is added to the buffer solution, then the salt reacts with base to form weak base and water, which does not alter the pH

NH₄Cl + CsOH → NH₃ + CsCl + H₂O
NH₄⁺ + OH⁻ → NH₃ + H₂O

When we add a strong acid to the buffer solution, the base NH₃ reacts with acid and forms salt, which does not alter the pH
NH₃ + H⁺ → NH₄⁺

5 0

3 years ago

Using what you have learned about the three forms of writing chemical equations, classify each of the presented equations as eit

suter [353]

Explanation:

Molecular equation: Chemical equation in which molecular formula of reactants and products are written

Complete ionic equation:Chemical equation in which ionic from if reactants reactants and products are written along with spectator ions (ions present on both sides of equation).

Net ionic equation :Chemical equation in which only ions of those reactant are written which giving product without spectator ions (ions present on both sides of equation).

(a) $Ca^{2+}(aq) + SO_4^{2-}(aq)\rightarrow CaSO_4(s)$