CR Chemistry A Module 1 Lesson 4

Questions and Answers

What is produced when lead(II) nitrate and potassium iodide react?

Lead(II) oxide

Iodine gas

Lead iodide (correct)

Potassium nitrate

Which of the following is a characteristic sign of a chemical reaction?

Change in color only

Evaporation of a liquid

Change in temperature

Formation of a new substance (correct)

What happens to the test tube when zinc reacts with hydrochloric acid?

It becomes warm (correct)

It stays the same temperature

It melts

It becomes cold

What process absorbs energy from the surroundings?

Melting of a solid Signup and view all the answers

Which visual clue indicates that a chemical reaction is likely occurring?

Gas being produced Signup and view all the answers

What is necessary to confirm that a chemical reaction has taken place?

Testing the composition of the substances Signup and view all the answers

What is formed as a result of the reaction between lead(II) nitrate and potassium iodide?

A yellow precipitate Signup and view all the answers

Which change indicates the absorption of energy?

Melting of ice Signup and view all the answers

In a chemical reaction, what happens to energy?

It may be transferred and not created or destroyed Signup and view all the answers

What is the most obvious sign that a pizza is done baking?

The crust turns light brown. Signup and view all the answers

Which of the following is NOT a visual clue indicating a chemical reaction?

Change in temperature Signup and view all the answers

What type of solid product is formed when lead(II) nitrate reacts with potassium iodide?

A yellow solid called a precipitate Signup and view all the answers

What happens to mercury(II) oxide when heated above 500°C?

It decomposes into mercury and oxygen gas. Signup and view all the answers

Which statement accurately describes the characteristics of a precipitate?

A solid product that settles out from a liquid mixture. Signup and view all the answers

When zinc reacts with hydrochloric acid, what is produced?

Hydrogen gas and bubbles. Signup and view all the answers

What indicator signifies a chemical reaction has likely occurred when observing color change?

The color shifts from red to silver. Signup and view all the answers

Which gas is produced when zinc reacts with hydrochloric acid?

Hydrogen gas. Signup and view all the answers

Which factor is NOT visual evidence of a chemical reaction?

A physical change in state Signup and view all the answers

What occurs to the dough of a pizza as it cooks?

It hardens and becomes solid. Signup and view all the answers

Study Notes

Cooking Pizza

Making a pizza can vary from purchasing a "take and bake" option to creating dough from scratch with various toppings.
Signs of a properly cooked pizza include a light brown crust, solidified dough, and melted cheese.
It is important to ensure the pizza is fully cooked rather than half-raw.

Recognizing Chemical Reactions

Four visual indicators of a chemical reaction:
- Color change occurs.
- Production of gas is observed.
- Formation of a solid precipitate happens.
- Energy transfer is noted.
Mercury(II) Oxide Reaction:
- Mercury(II) oxide is a red solid that decomposes above 500°C into mercury (silver) and oxygen gas.
- The color change from red (mercury oxide) to silver (mercury) signifies that a reaction has occurred.
Zinc and Hydrochloric Acid Reaction:
- The reaction between zinc and hydrochloric acid produces vigorous bubbling, indicating hydrogen gas formation.
Lead(II) Nitrate and Potassium Iodide Reaction:
- Mixing colorless lead(II) nitrate with colorless potassium iodide produces a yellow precipitate (lead iodide).
- The appearance of the yellow solid signals that a chemical reaction has taken place.
Energy Transfer during Reactions:
- Reactions can either release energy (exothermic) or absorb energy (endothermic).
- For example, zinc reacting with hydrochloric acid generates heat, causing the test tube to feel warm.
Testing for Chemical Reactions:
- To confirm that a chemical reaction has occurred, the composition of substances should be analyzed post-reaction to identify any changes compared to the original substances.

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Description

This quiz explores the chemical reactions involved in cooking, particularly focusing on making pizza. Learn about the signs that indicate a pizza is done, such as the crust color and cheese melting. Discover how culinary techniques relate to chemical changes.