Which liquid (water, black tea, or white vinegar) is most effective at making dull (tarnished) coins shiny?

Question

ScanSolve AI Tutor · Accepted Answer

Here are the answers to your practical task:

1. Write down the question that you want to answer.
The question to answer is: Which liquid (water, black tea, or white vinegar) is most effective at making dull (tarnished) coins shiny?

2. List the variables that will affect your results.

Type of liquid
Amount of liquid
Time the coin is left in the liquid
Initial dullness/tarnish of the coin
Type of coin material
Temperature of the liquid

3. Which variable will you change?
The variable that will be changed is the type of liquid (water, black tea, or white vinegar).

4. How will you make sure that the test is fair?
To ensure a fair test:

Use the same type of coin for each liquid.
Use equal amounts of each liquid.
Leave the coins in the liquid for the same amount of time (20 minutes).
Ensure the initial dullness of each coin is similar.
Keep the temperature of the liquids consistent.

5. List the apparatus and materials needed.

Dull (tarnished) coins
White vinegar
Water
Black tea (prepared)
Three saucers
Timer
Measuring cylinder/cup (to measure liquids)
Paper towels (for drying coins)
Pen and paper/workbook (for recording results)

6. List the steps of your investigation and then carry it out.

Gather all materials
three dull coins, three saucers, water, black tea, white vinegar, measuring cylinder, timer.
Label the three saucers
"Water", "Black Tea", "Vinegar".
Pour an equal amount (e.g., 50 mL) of water into the "Water" saucer, black tea into the "Black Tea" saucer, and white vinegar into the "Vinegar" saucer.
Place one dull coin into each saucer, ensuring it is fully submerged.
Start the timer for 20 minutes.
After 20 minutes, carefully remove each coin from its respective liquid.
Rinse each coin gently with water and dry it with a paper towel.
Observe and compare the appearance of each coin, noting any changes in shininess or tarnish removal.
Record the observations in the table.
10. Copy the table into your workbook and record your results.
Here are the expected results:
$\begin{array}{|l|l|} \hline \textbf{Substance} & \textbf{Appearance of coin} \\ \hline \text{water} & \text{Remains dull, no significant change.} \\ \hline \text{black tea} & \text{Slightly less dull, or no significant change.} \\ \hline \text{vinegar} & \text{Significantly shinier, tarnish removed.} \\ \hline \end{array}$
11. What conclusion can you make?
The conclusion is: White vinegar is the most effective liquid among water, black tea, and white vinegar for making dull (tarnished) coins shiny. Water and black tea have little to no effect on removing tarnish.

12. Evaluate your investigation. Did you have any problems? How could you improve your investigation?
Problems:
- Judging "shininess" is subjective and not quantitative.
- The initial dullness of the coins might not be uniform.
- Temperature of the liquids was not explicitly controlled. Improvements:
- Use a quantitative method to measure shininess (e.g., a light meter or a standardized visual scale).
- Use coins with uniform initial tarnish or pre-clean and re-tarnish them consistently.
- Control the temperature of the liquids (e.g., using a water bath).
- Repeat the experiment multiple times to ensure reliability of results.
- Test different concentrations of vinegar or different time durations to find optimal conditions.

Which liquid (water, black tea, or white vinegar) is most effective at making dull (tarnished) coins shiny?

Step-by-step solution

Gather all materials

Label the three saucers

Pour an equal amount (e.g., 50 mL) of water into the "Water" saucer, black tea into the "Black Tea" saucer, and white vinegar into the "Vinegar" saucer.

Place one dull coin into each saucer, ensuring it is fully submerged.

Start the timer for 20 minutes.

After 20 minutes, carefully remove each coin from its respective liquid.

Rinse each coin gently with water and dry it with a paper towel.

Observe and compare the appearance of each coin, noting any changes in shininess or tarnish removal.

Record the observations in the table.

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