# Ordering Rf of Aspirin with Polar Eluents

• cloveryeah
In summary, the correct order for increasing Rf of aspirin would be: n-hexane < ethyl acetate < n-butanol < methanol. This is because as the polarity of the solvent increases, the solubility of aspirin in the solvent also increases, leading to a higher Rf value.
cloveryeah

## Homework Statement

arrange the following eluents in an increasing order of Rf of aspirin

ethyl acetate, n-hexane, n-butanol, methanol

## The Attempt at a Solution

my order is n-hexane < n-butanol < ethyl acetate < methanol
but the order is wrong.
i am thinking: aspirin is polar, it will adhere onto the polar stationary phase.
with the increasing polarity of eluents, the Rf will increase as aspirin will dissolve more in the mobile phase.

So, what's wrong with my ans?

You are correct that you should order the solvents with increasing polarity, but you have incorrectly ordered them by polarity (one hint would be to look up the dielectric constant of the different solvents).

## 1. What is the purpose of ordering Rf of aspirin with polar eluents?

The purpose of ordering Rf (retention factor) of aspirin with polar eluents is to determine the polarity of the compound and its ability to interact with the polar mobile phase. This information can help in identifying the compound and its purity.

## 2. How is the Rf value of aspirin calculated?

The Rf value of aspirin is calculated by dividing the distance traveled by the compound by the distance traveled by the solvent front. This value is usually expressed as a decimal or a percentage.

## 3. What is the significance of using polar eluents in the Rf determination of aspirin?

Polar eluents are essential in the Rf determination of aspirin because they help in separating the different components of a mixture based on their polarity. Aspirin is a polar compound, so using polar eluents can improve its separation and resolution from other compounds in the mixture.

## 4. Can the Rf value of aspirin with polar eluents be used to identify the compound?

The Rf value of aspirin with polar eluents can give an indication of the compound's polarity and purity, but it is not enough to identify the compound. Other analytical techniques, such as spectroscopy, may be necessary for accurate identification.

## 5. What factors can affect the Rf value of aspirin with polar eluents?

Several factors can affect the Rf value of aspirin with polar eluents, including the type and concentration of the eluent, the type of stationary phase, the temperature, and the humidity. These factors can alter the interactions between the compound and the mobile phase, affecting its Rf value.

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