What will be the first solvent that will be used to extract the caffeine from the tea? Group of answer choices Dichloromethane Ethyl acetate Hexane Water

🧪 What Will Be the First Solvent Used to Extract the Caffeine from Tea?

📌 Question:

What will be the first solvent that will be used to extract the caffeine from the tea?

• Dichloromethane
• Ethyl acetate
• Hexane
• Water ✅

💡 Full Detailed Explanation

Caffeine extraction from tea is a classic example of a multi-step chemical separation procedure often used in organic chemistry and biochemistry labs. The initial step of this process plays a crucial role in determining the efficiency and purity of the caffeine yield. This is where the choice of the first solvent becomes essential.

🔬 Why Water is Used First

The extraction begins with brewing tea in hot water. This step is scientifically referred to as the aqueous extraction. Water, being a polar solvent, has a high capability to dissolve various compounds, including:

• Caffeine
• Flavonoids
• Tannins
• Theophylline and other alkaloids

When hot water is poured over the tea leaves, the caffeine present within the leaves quickly diffuses into the solution. Due to its high solubility in hot water—especially above 70°C—caffeine becomes part of the aqueous phase. At this point, the caffeine is no longer within the plant matrix but dissolved in water, along with other organic solutes.

🌡️ Solubility of Caffeine in Water

The solubility of caffeine in water increases with temperature:

• At 25°C: ~21 g/L
• At 78°C: ~200 g/L
• At 100°C: ~666 g/L

This high solubility at elevated temperatures supports water’s effectiveness as the first solvent in caffeine extraction from tea. Boiling or near-boiling water ensures maximum dissolution of caffeine and other polar molecules.

🧪 What Comes After Water?

Once caffeine has been extracted into the water, the solution still contains a mix of various compounds. To isolate caffeine, a liquid-liquid extraction is then performed using a less polar organic solvent, commonly:

• Dichloromethane (DCM): High affinity for caffeine
• Ethyl acetate: Moderate efficiency
• Chloroform or hexane: Less common, less effective for caffeine

The organic solvent is added to the aqueous caffeine solution in a separatory funnel. Due to its chemical properties, caffeine prefers the organic layer and migrates into it, leaving behind more water-soluble impurities.

📘 Why Not Start with Organic Solvent?

Tea leaves are plant-based, dry matter. Caffeine is locked inside plant cells and is not accessible until the leaves are soaked. An organic solvent like dichloromethane cannot penetrate the cellulose structure effectively in dry form. Water softens and swells the leaf structure, releasing the caffeine into solution. Only then can an organic solvent be used to separate it efficiently.

🔁 Summary of the Extraction Sequence

1. Step 1: Steep tea leaves in hot water (first solvent)
2. Step 2: Filter or decant the aqueous extract
3. Step 3: Add organic solvent like dichloromethane for separation
4. Step 4: Isolate organic layer and evaporate to obtain caffeine crystals

📊 Practical Implications in Labs

This question is commonly asked in both academic settings and entrance exams to test conceptual clarity. Understanding why water is the first solvent helps students differentiate between:

• Solubility vs. Partitioning
• Polar vs. Non-polar solvents
• Extraction vs. Isolation processes

It also emphasizes the importance of procedure order and logical sequencing in lab work.

📚 Educational Value

Knowing the correct solvent sequence lays the foundation for more advanced topics in organic chemistry, such as:

• Green extraction methods
• Phase transfer catalysis
• Multistep synthesis and separation
• Analytical chemistry techniques