Animated Solution for Chemistry - Basic Concepts in Chemistry: 1.86 g of aniline completely reacts to form acetanilide. 10% of the product is lost during purification. Amount of acetanilide obtained after purification (in g) is ……… $\times 10^{-2}$.

Imagine you are in a chemistry lab, carefully setting up an acetylation reaction. You start with aniline ($C_6{H}_{5}N{H}_2$), a primary aromatic amine, and react it with an acetylating agent to form acetanilide ($C_6{H}_{5}NHCOC{H}_3$).

The stoichiometry of this reaction is beautifully simple: one molecule of aniline yields exactly one molecule of acetanilide. This 1:1 molar ratio is the foundation of our calculation. The question states that we are starting with $1.86\text{ g}$ of aniline.

Theoretical Yield

Before we worry about the real-world losses, let's calculate what we should get in a perfect scenario. This is called the theoretical yield.

First, we need the molar masses of our compounds. For aniline ($C_6{H}_{5}N{H}_2$), the molar mass is $6(12)+5(1)+14+2(1)=93\text{ g/mol}$. For acetanilide ($C_6{H}_{5}NHCOC{H}_3$), the molar mass is $8(12)+9(1)+14+16=135\text{ g/mol}$.

Using the mole concept, we equate the moles of aniline to the theoretical moles of acetanilide:

Solving this gives us the theoretical mass:

Actual Yield

Now, here is the catch. The problem states that 10% of the product is lost during purification. In practical chemistry, processes like crystallization, filtration, or transferring substances between flasks inevitably lead to some loss of material.

If 10% is lost, it means we only successfully recover 90% of our theoretical yield. Let's calculate the actual mass obtained:

Finally, we must format our answer exactly as requested. The question asks for the value in the form of $x\times 10^{-2}$.

Therefore, the integer value we are looking for is 243.