All categories

4 years ago

Please help with an easy percentage yield question ASAP!!! Would really appreciate!

Chemistry

1 answer:

Brut [27]4 years ago

7 0

Answer:

The mass percentage yield is 85%

Explanation:

Step 1: The balanced equation

2 C7H6O3 + (CH3CO)2CO → 2 C9H8O4 + H20

Step 2: Given data

mass of salicylic acid = 1.03 grams

Volume of acetic anhydride = 2.00 mL = 2*10^-3 L

The product is 1.16 g aspirin synthesized

Molar mass of salicylic acid = 138.12 g/mole

Molar mass of aspirin = 180.16 g/mole

Density of acetic anhydride = 1.0820 g/mL

Step 3: Calculated moles of salicylic acid

Number of moles of salicylic acid = mass of salicylic acid / Molar mass of salicylic acid

Number of moles of salicylic acid = 1.03 grams / 138.12 g/mole

Number of moles of salicylic acid =0.0075 moles

Step 4: Calculated mass acetic anhydride

mass of acetic anhydride = 1.0820 g/mL * 2 mL = 2.164 grams

Step 5: Calculate number of moles of acetic anhydride

Number of moles = 2.164 grams / 102.09 g/moles

Number of moles = 0.0212 moles

Step 6: Find amount of reacting moles

C7H6O3 is the limiting reactant, there will react 0.0075 moles

Since for 2 moles C7H6O3 consumed, we need 1 mole of (CH3CO)2CO to produce 2 moles of C9H804

So for 0.0075 moles C7H6O3 consumed, we produce 0.0075 moles of C9H8O4

Step 7: Calculate mass of aspirin

mass of aspirin = 0.0075 moles * 180 g/mole = 1.35 grams

Step 8: Calculate the mass percentage yield

(1.16 grams / 1.35 grams) * 100% = 85 %

The mass percentage yield is 85%

You might be interested in

Water is not found on the Periodic Table of Elements because water is:

vovangra [49]

Water is a compound. H2O

7 0

3 years ago

Read 2 more answers

Which hypothesis is most supported by astronomers?

sladkih [1.3K]

Answer:

option A is the most supported hypothesis by astronomers

3 0

2 years ago

Which is the fastest in the universe apart from the light

Salsk061 [2.6K]

Well i did some research and i found out now im not sure if this is completely true but supposedly tachyons are even faster than the speed of light

3 0

3 years ago

Temperate deciduous trees lose their leaves in Fall. Explain why trees in temperate rainforest and tropical rainforest don’t los

andrey2020 [161]

Answer:

So trees in temperate don't lose their leaves because the weather events aren't harsh enough.

Trees in tropical rainforest don't lose their leaves because they are a different type of tree known as evergreens that are green all year round.

Explanation:

Ok so first we'll define some things

Deciduous Trees= Trees that lose all of their leaves for part of the year.

Trees shed their leaves trees to try and survive harsh weather events.

Temperate deciduous trees lose their leaves in fall to better survive the winter conditions of extreme cold and reduced daylight.

Temperate rainforests = An area that doesn't experience extremely cold or extremely hot temperatures or what we would call harsh weather events.

Broad-leaved trees in tropical rainforests are known evergreen, they are known as this as they are green all year round.

6 0

3 years ago

A 1-liter solution contains 0.494 M hydrofluoric acid and 0.371 M potassium fluoride. Addition of 0.408 moles of hydrochloric ac

UkoKoshka [18]

Answer:

Option f: an addition of HCl will exceed the buffer capacity. The option d is also correct since it is a consequence of the option f.

Explanation:

The pH of the buffer solution before the addition of HCl is:

$pH = pKa + log(\frac{[KF]}{[HF]})$

$pH = -log(6.8 \cdot 10^{-4}) + log(\frac{0.371}{0.494}) = 3.04$

The hydrochloric acid added will react with the potassium fluoride as follows:

H₃O⁺(aq) + F⁻(aq) ⇄ HF(aq) + H₂O(l)

The number of moles (η) of potassium fluoride (KF) and the HF before the addition of HCl is:

$\eta_{KF}_{i} = C_{KF}*V = 0.371 M*1 L = 0.371 mol$

$\eta_{HF}_{i} = C_{HF}*V = 0.494 M*1 L = 0.494 moles$

The number of moles of the HCl added is 0.408 moles. Since the number of moles of HCl is bigger thant the number of moles of KF, the moles of HCl that remains after the reaction is:

$\eta_{HCl} = \eta_{HCl} - \eta_{KF}_{i} = 0.408 moles - 0.371 moles = 0.037 moles$

Hence, the KF is totally consumed after the reaction with HCl and thus, exceding the buffer capacity.

We can calculate the pH after the addition of HCl:

HF(aq) + H₂O(l) ⇄ F⁻(aq) + H₃O⁺(aq) (1)

The number of moles of HF after the reaction of KF with HCl is:

$\eta_{HF} = 0.494 moles + (0.408 moles - 0.371 moles) = 0.531 moles$

And the concentration of HF after the reaction of KF with HCl is is:

$C_{HF} = \frac{\eta_{HF}}{V} = \frac{0.531 moles}{1 L} = 0.531 moles/L$

Now, from the equilibrium of equation (1) we have:

$Ka = \frac{[H_{3}O^{+}][F^{-}]}{[HF]}$

$Ka = \frac{x^{2}}{0.531 - x}$ (2)

By solving equation (2) for x we have:

x = 0.0187

Finally, the pH after the addition of HCl is:

$pH = -log (H_{3}O^{+}) = -log (0.0187) = 1.73$

Therefore, the addition of HCl will exceed the buffer capacity and thus, lower the pH by several units. The correct option is f: an addition of HCl will exceed the buffer capacity. The option d is also correct since it is a consequence of the option f.

I hope it helps you!

8 0

4 years ago