Chromatography exercise - Free Printable

Problem Analysis:

The image provided is a worksheet on chromatography, specifically focusing on simple paper chromatography. The diagram shows the setup and results of a chromatography experiment, where ink is separated into its component colors using water as the solvent. Below are the questions and their solutions:

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Question 1: How many colours is the ink made from?

#### Solution:
From the diagram on the right side (labeled "End"), we can observe the separated ink spots. The ink has been resolved into 7 distinct colors. These colors are visible as separate bands on the paper strip.

#### Answer:
$$
\boxed{7}
$$

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Question 2: Which direction does the water travel?

#### Solution:
In paper chromatography, the solvent (water in this case) travels upward along the paper strip due to capillary action. Capillary action causes the liquid to move through the tiny spaces in the paper, pulling the ink components with it.

#### Answer:
$$
\boxed{\text{Upward}}
$$

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Question 3: Why is the ink spot not exactly in the water?

#### Solution:
The ink spot is placed above the level of the water in the beaker for several reasons:

1. Prevent Dissolution: If the ink spot were directly in the water, it would dissolve immediately without separating into its components. By placing it above the water, the ink only begins to dissolve when the water reaches it, allowing controlled separation.

2. Controlled Separation: Placing the ink spot above the water ensures that the separation process occurs gradually as the water rises up the paper. This allows different ink components to separate based on their solubility and affinity for the paper.

3. Avoid Contamination: Keeping the ink spot above the water prevents direct mixing with the solvent, which could lead to incomplete or inaccurate separation.

#### Answer:
$$
\boxed{\text{To prevent immediate dissolution and allow controlled separation of ink components as the water rises.}}
$$

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Final Answers:

1. $$ \boxed{7} $$
2. $$ \boxed{\text{Upward}} $$
3. $$ \boxed{\text{To prevent immediate dissolution and allow controlled separation of ink components as the water rises.}} $$

This completes the solution to the worksheet questions. Let me know if you need further clarification!