CR Chemistry A Module 1 Lesson 4

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.

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.