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3 years ago

What is the difference between an imprint and an impression?

Chemistry

1 answer:

liubo4ka [24]3 years ago

5 0

Answer:

As nouns the difference between impression and imprint

is that impression is the indentation or depression made by the pressure of one object on or into another while imprint is an impression; the mark left behind by printing something.

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What is the past tense of I'll

yan [13]

Answer:

i would or i have or i did

Explanation:

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3 years ago

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Aspirin sun thesis Green Chemistry and Assime the aspirin is prepared by the following reaction and that 10.09. of salicylic aci

klemol [59]

Answer: The percentage yield of aspirin is 38.02 %.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For salicylic acid:

Given mass of salicylic acid $(C_7H_6O_3)$ = 10.09 g

Molar mass of salicylic acid $(C_7H_6O_3)$ = 138.12 g/mol

Putting values in equation 1, we get:

$\text{Moles of salicylic acid}=\frac{10.09g}{138.12g/mol}=0.0730mol$

The chemical equation for the formation of aspirin follows:

$C_7H_6O_3+C_4H_6O_3\rightarrow C_9H_8O_4+CH_3COOH$

As, acetic anhydride is present in excess. So, it is considered as an excess reagent.

Thus, salicylic acid is a limiting reagent because it limits the formation of products.

By Stoichiometry of the reaction:

1 mole of salicylic acid produces 1 mole of aspirin.

So, 0.0730 moles of salicylic acid will produce = $\frac{1}{1}\times 0.0730=0.0730mol$ of aspirin

Now, calculating the mass of aspirin from equation 1, we get:

Molar mass of aspirin = 180.16 g/mol

Moles of aspirin = 0.073 moles

Putting values in equation 1, we get:

$0.073mol=\frac{\text{Mass of aspirin}}{180.16g/mol}\\\\\text{Mass of aspirin}=13.15g$

To calculate the percentage yield of aspirin, we use the equation:

$\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

Experimental yield of aspirin = 5.0 g

Theoretical yield of aspirin = 13.15 g

Putting values in above equation, we get:

$\%\text{ yield of aspirin}=\frac{5.0g}{13.15g}\times 100\\\\\% \text{yield of aspirin}=38.02\%$

Hence, the percent yield of aspirin is 38.01 %.

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3 years ago

An amide may be produced by reacting an acid chloride with

Elanso [62]

Answer:

An amide may be produced by reacting an acid chloride with ammonia.

8 0

3 years ago

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What is the pH of a 0.640 M solution of C₅H₅NHBr (Kb of C₅H₅N is 1.7 × 10⁻⁹)?

Elden [556K]

The pH of a 0.64 M solution of pyridine (C₅H₅N) is 9.52.

A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.

The equation for the protonation of the base pyridine is the following:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻ (1)

Kb = 1.7 × 10⁻⁹ (Given)

To calculate the pH of the solution we need to use the following equation:

pH + pOH = 14

pH = 14 - pOH

=14 - [-log[OH⁻]]

= 14 + log[OH⁻]

Now, we need to find the concentration of the OH⁻ ions. Since pyridine is a weak base, at the equilibrium we have (eq 1):

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻

0.64 - x x x

After entering the values of [C₅H₅N] = 0.64-x, [C₅H₅NH⁺] = x, and [OH⁻] = x, into equation (2) we can find the concentration of OH⁻:

1.7 × 10⁻⁹ =[C₅H₅NH⁺] [OH⁻] / [C₅H₅N]

= x . x / 0.64-x

1.7 × 10⁻⁹ (0.64-x) - x² = 0

Solving the above quadratic equation for x, we have :

x₁ = -3.32 x 10⁻⁵
x₂ = 3.32 x 10⁻⁵

Now, We can calculate the pH, after taking the positive value, x₂, (concentrations cannot be negative) and entering into above equation :

pH = 14 + log[OH⁻]

= 14 + log (3.32 x 10⁻⁵)

= 9.52

Therefore, the pH of the solution of pyridine is 9.52.

Find more about pH here:

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2 years ago

A) ambos pertencem ao 5o período da Tabela Periódica;

Reptile [31]

Answer:

Explanation:

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3 years ago