Question 1: Define density in terms of mass and volume. Provide the formula used to calculate density.

Answer: Density is the mass per unit volume of a substance, calculated as density = mass / volume, with units of kg/m^3 or g/cm^3.

Question 1: Explain how the particle model describes the difference in density between a solid and a gas.

Answer: The particle model shows that solids have particles tightly packed together, resulting in higher density, while gases have particles spread far apart, resulting in lower density.

Question 2: Which of the following materials generally has a higher density: aluminum, sulfur, or plastic? Provide a brief explanation.

Answer: Aluminum

Question 1: A sample of metal has a mass of 150 grams and a volume of 50 cm^3. Calculate its density in g/cm^3.

Answer: Density = mass / volume = 150 g / 50 cm^3 = 3 g/cm^3

Question 2: A student measures the density of a plastic block and finds it to be 0.95 g/cm^3. If the block's volume is 200 cm^3, what is its mass?

Answer: Mass = density × volume = 0.95 g/cm^3 × 200 cm^3 = 190 g

Question 3: A piece of aluminum has a mass of 270 grams and a density of 2.7 g/cm^3. What is its volume?

Answer: Volume = mass / density = 270 g / 2.7 g/cm^3 = 100 cm^3

Question 1: Describe a simple method to measure the volume of an irregularly shaped object in a density experiment.

Answer: Use water displacement: submerge the object in a measured amount of water and record the increase in water level to find its volume.

Question 2: Identify at least two variables that must be controlled during a density experiment and explain why.

Answer: Variables include temperature, to prevent density changes due to thermal expansion, and measurement accuracy, to ensure precise mass and volume readings.

Question 3: List two safety precautions that should be followed when handling materials in density experiments involving chemicals.

Answer: Wear protective gloves and safety goggles to prevent chemical contact and splashes.

Question 1: A manufacturer uses density to identify materials in recycling: aluminum foil has a density around 2.7 g/cm^3, while plastic varies from 0.9 to 1.4 g/cm^3. How can density help in sorting recyclable materials?

Answer: Density allows sorting by measuring mass and volume; materials with densities close to known values can be identified and separated efficiently.

Question 2: Explain how the concept of density is important in designing ships and submarines.

Answer: Designers use density to ensure ships float by making overall density less than water. Submarines control their density by adjusting ballast tanks to submerge or surface, relying on principles of density to achieve stability and buoyancy.