Question

1. why do we need to know the chemical properties of substances in industries like medicine or construction? (2 points)

section b: application

1. a car is left outside during rainy weather and starts to form rust. a) what chemical property does this demonstrate? b) what evidence shows that a chemical change occurred? (3 points)
2. your friend says boiling water is a chemical change because bubbles are formed. do you agree or disagree? explain your reasoning. (3 points)
3. think about the last time you cooked food (boiling an egg, baking a cake, etc.). describe one chemical property involved in the process. (2 points)

section c: critical thinking

1. some metals like gold do not react with oxygen or water easily. why do you think gold is used in jewelry and electronics? (3 points)
2. imagine scientists discover a new metal that reacts violently with air. what precautions should they take when studying its properties? (3 points)

Explanation:

1. In medicine, knowledge of chemical properties helps in drug - formulation, ensuring efficacy and safety. In construction, it aids in material - selection for durability and stability.
2. a) The car forming rust demonstrates the chemical property of reactivity with oxygen and water (oxidation). b) Evidence of a chemical change includes the formation of a new substance (rust), a change in color, and loss of the original metal's properties.
3. Disagree. Boiling water is a physical change. The bubbles are water vapor, and no new substance is formed. Water changes from liquid to gas and can be reversed by cooling.
4. When baking a cake, the chemical property of baking powder reacting with an acid (e.g., vinegar in some recipes) to produce carbon - dioxide gas is involved, which causes the cake to rise.
5. Gold is used in jewelry because of its non - reactivity (it doesn't tarnish easily), beautiful color, and malleability. In electronics, its non - reactivity ensures stable electrical connections and resistance to corrosion.
6. Scientists should study the metal in an inert gas environment to prevent reaction with air. They should use protective gear like gloves, goggles, and lab coats, and work in a well - ventilated fume hood.

Answer:

1. In medicine, for drug - making and safety; in construction, for material choice.
2. a) Reactivity with oxygen and water. b) New substance formation, color change, loss of original properties.
3. Disagree. No new substance formed; physical change.
4. Baking powder reacting to produce carbon - dioxide in cake - baking.
5. In jewelry: non - reactivity, color, malleability. In electronics: non - reactivity for stable connections.
6. Use inert gas environment, protective gear, work in fume hood.