Final answer:
To identify the presence of benzene in a liquid, gas chromatography can be used. The percentage of benzene in a liquid can be found by calculating the mass or volume ratio.
Simple tests like immiscibility with water and the bromine test can also indicate the presence of benzene.
Step-by-step explanation:
To identify the presence of benzene in a liquid, one option is to use gas chromatography. Gas chromatography is a technique that separates and analyzes the components of a mixture.
The liquid sample is injected into the gas chromatograph, which vaporizes the sample and separates the components based on their different interactions with the stationary phase and mobile phase.
Benzene can be detected by its specific retention time in the chromatogram.
To find the percentage of benzene in a liquid, you can calculate it using the mass or volume ratio.
For example, if you know the mass of benzene and the total mass of the liquid, you can calculate the percentage by dividing the mass of benzene by the total mass and multiplying by 100.
Alternatively, if you know the volume of benzene and the total volume of the liquid, you can use the same method with volumes.
With a chemistry lab that has the bare minimum necessities, you may not have access to advanced equipment like a gas chromatograph.
However, other simple tests can be done to indicate the presence of benzene, although they may not provide precise quantitative results.
For example, benzene is immiscible with water, so if you mix the liquid with water and observe the formation of two distinct layers, one of which smells like gasoline, it suggests the presence of benzene.
Another test is the bromine test, where bromine water is added to the liquid sample; if the color of the bromine water fades, it indicates the unsaturation of benzene.