Conductors, Electricity and Circuits

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Questions and Answers

Why is it more accurate to classify materials as 'good conductors' and 'poor conductors' rather than 'conductors' and 'insulators'?

Because all materials completely block the flow of electricity under specific conditions.
Because only pure elements can be definitively classified as either conductors or insulators.
Because most materials can conduct electricity to some extent under certain conditions. (correct)
Because the terms `conductor` and `insulator` are outdated and no longer used in modern science.

Why is distilled water a poor conductor of electricity, while tap water is a good conductor?

Tap water contains dissolved gases that enhance conductivity.
Tap water is artificially ionized to improve its conductivity.
Distilled water lacks dissolved salts and minerals, unlike tap water. (correct)
Distilled water is always at a lower temperature, which reduces its conductivity.

What type of solutions are typically good conductors of electricity?

Solutions of acids, bases, and salts. (correct)
Solutions with neutral pH levels and no dissolved substances.
Solutions containing high concentrations of non-polar solvents.
Solutions containing large organic molecules such as sugars.

Why should one avoid handling electrical appliances with wet hands or while standing on a wet floor?

Water, especially if not pure, can conduct electricity, increasing the risk of electric shock. (B) Signup and view all the answers

Activity 11.6 describes using carbon rods from discarded cells as electrodes. What is the primary purpose of using these electrodes in a circuit with a conducting solution?

To facilitate the flow of electric current through the solution. (A) Signup and view all the answers

If a solution conducts electricity, what effect does the electric current have on the solution?

It induces a chemical change in the solution. (D) Signup and view all the answers

A student tests a solution and finds it conducts electricity. However, when the concentration of the solute is significantly reduced, the conductivity decreases. What is the most likely explanation for this?

Fewer charge carriers are available in the solution. (C) Signup and view all the answers

A scientist is investigating the conductivity of different water samples. Sample A is collected from a freshwater lake, and Sample B is distilled water. Both samples are at the same temperature. Which of the following statements is most likely true?

Sample A will conduct electricity better than Sample B because it contains dissolved mineral salts. (B) Signup and view all the answers

In Nicholson's experiment with electrolysis of water, what observation directly indicated a chemical reaction was occurring?

Bubbles of oxygen and hydrogen formed on the electrodes. (A) Signup and view all the answers

What did Boojho and Paheli discover about the wire connected to the positive terminal of the battery when they repeated Nicholson's experiment?

It had a greenish-blue spot around it, indicating a chemical reaction. (C) Signup and view all the answers

Boojho set out to test whether a potato conducted electricity, but he observed a chemical effect instead. Which of the following best describes the significance of this experience?

It exemplifies how unexpected observations can lead to new scientific discoveries. (D) Signup and view all the answers

Based on the text, which of the following is NOT a chemical effect of electric current passing through a conducting solution?

Increase in the temperature of the solution (B) Signup and view all the answers

In the experiment with the potato, the greenish-blue spot observed near the positive terminal is LEAST likely due to:

Deposition of a new metal forming on the electrode. (B) Signup and view all the answers

Suppose you replicate Nicholson’s experiment using a saltwater solution instead of pure water. How would you expect the results to differ, if at all?

The rate of gas production would likely increase due to the higher conductivity of saltwater. (D) Signup and view all the answers

If a scientist aims to determine the unknown identity of a solution using only the chemical effects of electric current and a known metal electrode, which observation would be MOST helpful?

The color of the gas produced at the negative electrode. (D) Signup and view all the answers

Considering the chemical effects of electric current, what implications does this phenomenon have for industrial processes? Select the MOST accurate answer.

It can be harnessed for electroplating, metal refining, and the production of various chemicals. (D) Signup and view all the answers

In electroplating, what is the purpose of adding a few drops of dilute sulfuric acid to the copper sulfate solution?

To make the solution more conductive. (D) Signup and view all the answers

During electroplating with a copper sulfate solution, where does the copper that is deposited on the object originate from?

It comes from the dissociation of copper sulfate in the solution. (D) Signup and view all the answers

If Paheli interchanged the electrodes in the electroplating experiment, what would she likely observe?

Copper would be deposited on the previously positive electrode. (D) Signup and view all the answers

What happens to the copper at the positive electrode during the electroplating of copper onto another object?

The copper electrode dissolves, replenishing copper ions in the solution. (B) Signup and view all the answers

Why do some artificial gold ornaments lose their shine and reveal a different metal underneath with repeated use?

The gold coating wears off due to physical abrasion. (A) Signup and view all the answers

In the electroplating process described, what is the net effect on the concentration of copper sulfate in the solution, assuming the process is running efficiently?

The concentration of copper sulfate remains approximately the same. (C) Signup and view all the answers

Consider a scenario where the copper sulfate solution is contaminated with chloride ions. How might this affect the electroplating process?

It could lead to the formation of copper chloride at the anode, affecting the plating quality. (A) Signup and view all the answers

A student wants to electroplate a key with copper. Based on the setup described, what should the student connect the key to in the circuit?

The negative terminal of the battery. (B) Signup and view all the answers

In the experiment testing conductivity of solutions, what is the primary purpose of adding lemon juice or salt to the water?

To increase the concentration of $H^+$ ions, enhancing its electrical conductivity. (A) Signup and view all the answers

Why should the metal caps of the carbon rods remain outside the water during the conductivity experiment?

To ensure that the electrical connection is not short-circuited by the water. (A) Signup and view all the answers

What observation during the electrolysis of water would suggest that a chemical change is occurring?

The formation of gas bubbles near the electrodes. (C) Signup and view all the answers

In Boojho's potato experiment, what is the most likely cause of the greenish-blue spot appearing around one of the copper wires?

Oxidation of the copper wire due to electrolysis, forming copper compounds. (C) Signup and view all the answers

When testing conductivity of different solutions, which of the following would likely result in a solution that does NOT conduct electricity?

A solution of sugar. (A) Signup and view all the answers

Based on the experimental setup described, what is the most likely reason for using distilled water instead of tap water?

Distilled water minimizes interference from ions already present in tap water. (D) Signup and view all the answers

How does the addition of a base, such as caustic soda, to distilled water affect its ability to conduct electricity?

It increases conductivity by providing mobile ions in the solution. (B) Signup and view all the answers

What is the fundamental difference between the effect of sugar and salt on the electrical conductivity of water?

Salt dissociates into ions in water, enabling conductivity, while sugar does not. (B) Signup and view all the answers

Why is chromium often used as a coating rather than for the entire object in electroplating?

Chromium is expensive, making it uneconomical for entire objects. (A) Signup and view all the answers

What is a primary environmental concern associated with electroplating factories?

The disposal of used conducting solutions. (A) Signup and view all the answers

What is the fundamental process underlying the chemical effects of electric currents in liquids?

Chemical reactions caused by the electric current. (B) Signup and view all the answers

What is the term for the process of coating one metal with a layer of another metal using electricity?

Electroplating (D) Signup and view all the answers

During the electrolysis of copper sulfate solution, where does copper get deposited?

On the negative terminal of the battery. (A) Signup and view all the answers

Why does a magnetic needle deflect when the free ends of a tester are dipped into a solution?

The solution conducts electricity, creating a magnetic field. (C) Signup and view all the answers

Which of the following liquids, when tested for conductivity, would likely cause a magnetic needle to deflect?

Vinegar (B) Signup and view all the answers

In an electroplating setup where copper is transferred from one electrode to another, what is the primary mechanism that sustains the process?

The oxidation of copper atoms at the anode replenishes the copper loss in the solution. (D) Signup and view all the answers

Boojho replaced the copper plate connected to the negative terminal with a carbon rod and successfully coated it with copper. What does this experiment demonstrate about electroplating?

The material of the cathode does not affect the electroplating process as long as it is conductive. (B) Signup and view all the answers

Why is electroplating widely used in various industries?

It allows for modifying the surface properties of a material without changing its bulk properties. (B) Signup and view all the answers

Chromium plating is often used on car parts and kitchen appliances. Which combination of properties makes chromium suitable for these applications?

Shiny appearance and resistance to corrosion. (D) Signup and view all the answers

Why are ornaments often made by electroplating silver or gold onto less expensive metals?

To achieve the desired appearance at a lower cost. (C) Signup and view all the answers

Tin cans, commonly used for storing food, are made by electroplating tin onto iron. What is the primary reason for using tin as the coating material?

Tin is less reactive than iron, preventing food contamination. (A) Signup and view all the answers

Iron used in bridges and automobiles is often coated with zinc. Which property of zinc makes it suitable for protecting iron in these applications?

Zinc is more resistant to corrosion than iron, even when scratched. (D) Signup and view all the answers

A metal object has been electroplated. Which of the following characteristics is most likely to be determined by the metal used in the electroplating process, rather than the object itself?

The object's surface appearance. (C) Signup and view all the answers

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Flashcards

Conductors vs. Insulators

Materials are classified by how well they conduct electricity.

Salt Solution

A solution formed when salt is dissolved in distilled water; it conducts electricity.