Atomic number describes which of the following?
2 answers:
Answer:
The correct answer is option C.
Explanation:
Atomic weight is defined as sum of protons and neutrons present in the nucleus of an atom of the particular element.It is denoted by A.
Atomic number is defined as total number of protons present in the nucleus of an atom of the particular element. It is denoted by Z.
For an element say with X symbol both atomic weight and number are denoted by: .
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<u>Answer:</u> The percentage yield of aspirin is 38.02 %.
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
.....(1)
- <u>For salicylic acid:</u>
Given mass of salicylic acid = 10.09 g
Molar mass of salicylic acid = 138.12 g/mol
Putting values in equation 1, we get:
The chemical equation for the formation of aspirin follows:
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 = 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:
To calculate the percentage yield of aspirin, we use the equation:
Experimental yield of aspirin = 5.0 g
Theoretical yield of aspirin = 13.15 g
Putting values in above equation, we get:
Hence, the percent yield of aspirin is 38.01 %.