Matter and Its Interactions Practice
Unit: Matter and Its Interactions - Practice (Lessons 2, 3, and 4)
Learning Objectives
Apply knowledge of intensive and extensive properties, including density calculations, to identify substances and solve problems
Explain particle behavior in each state of matter and describe how thermal energy drives all six phase changes
Distinguish conduction, convection, and radiation and apply the concepts of conductors and insulators to real-world situations
Properties of Matter Review
~3 minutesSection 1: Properties of Matter Review
Physical properties let scientists observe and measure matter without changing it into a different substance. These properties fall into two categories. Intensive properties stay the same no matter how much of the substance you have. Density, melting point, boiling point, and solubility are all intensive. Because they are constant for a given substance, scientists use them like a fingerprint to identify what the substance is. Extensive properties change when the amount of substance changes. Mass, volume, and weight are extensive. They tell you how much matter is present, but not what the matter is.
Density is one of the most useful intensive properties. It is calculated with the formula d = m / V (density equals mass divided by volume). Density determines whether an object floats or sinks: anything with a density less than water (1.0 g/mL) will float, and anything with a density greater than water will sink.
Intensive property: a physical property that does NOT change with amount (density, melting point, boiling point, solubility). Extensive property: a physical property that DOES change with amount (mass, volume, weight). Density: mass per unit volume (d = m/V), measured in g/cm3 or g/mL. Solubility: how much solute dissolves in a given amount of solvent at a specific temperature.
Properties of Matter Questions
A scientist measures the boiling point of a small beaker of liquid and gets 78 degrees Celsius. She then repeats the measurement using a much larger container of the same liquid. What boiling point will she record?
A student has a block of unknown material with a mass of 240 g and a volume of 30 cm cubed. She calculates the density and wants to identify the material. Which density value did she find, and which substance does it most likely match?
A wooden log and a wooden toothpick have different densities because the log is much larger.
A property that does NOT change with the amount of substance and can be used to identify what the substance is, is called a(n) ______ property.
A solid cube with a density of 2.3 g/mL is dropped into a container of honey (density 1.42 g/mL). A hollow plastic ball with a density of 0.5 g/mL is dropped into the same container. What happens?
States of Matter and Phase Changes Review
~3 minutesSection 2: States of Matter and Phase Changes Review
All matter is made of particles in constant motion, an idea known as the kinetic molecular theory. Temperature measures the average kinetic energy of those particles. In a solid, particles are tightly packed in a fixed grid and only vibrate in place, giving solids a definite shape and definite volume. In a liquid, particles are close together but slide past each other, so liquids have a definite volume but take the shape of their container. In a gas, particles are far apart and move rapidly in all directions, filling any container completely.
Matter changes state through phase changes, which are caused by adding or removing thermal energy. Adding energy causes melting (solid to liquid), evaporation or boiling (liquid to gas), and sublimation (solid to gas directly). Removing energy causes freezing (liquid to solid), condensation (gas to liquid), and deposition (gas to solid directly). During any phase change, the temperature stays constant because the energy goes into breaking or forming bonds between particles rather than changing the temperature. This creates flat plateaus on a heating curve.
Kinetic molecular theory: all matter is made of particles in constant motion; temperature measures average kinetic energy. Melting: solid to liquid (energy added). Freezing: liquid to solid (energy removed). Evaporation/Boiling: liquid to gas (energy added). Condensation: gas to liquid (energy removed). Sublimation: solid to gas directly (energy added). Deposition: gas to solid directly (energy removed). Heating curve: a graph of temperature vs. energy added, with flat plateaus at each phase change.
States and Phase Changes Questions
Which statement correctly describes particle behavior in a liquid?
When ice is melting at 0 degrees Celsius, adding more heat will cause the temperature to rise above 0 degrees before all the ice has melted.
Which of the following phase changes require energy to be REMOVED from the substance? (Select all that apply)
Select all that apply.
In the morning, you notice frost has formed on a car windshield overnight. The water vapor in the air changed directly into solid ice crystals. This phase change is called ______.
A beaker of ice at negative 10 degrees Celsius is placed on a hot plate. Arrange the following events in the order they occur as energy is continuously added.
Energy Transfer Review
~3 minutesSection 3: Energy Transfer Review
Thermal energy always flows from warmer objects to cooler objects, never the other way around. This flow continues until both objects reach the same temperature, a state called thermal equilibrium. Heat moves by three methods. Conduction transfers energy through direct contact between particles and works best in solids, especially metals (good conductors). Materials that resist heat flow, such as wood, plastic, and air, are called insulators. Convection transfers energy through the circulation of fluids (liquids and gases). Warm fluid rises because it becomes less dense, and cooler fluid sinks, creating a loop called a convection current. Radiation transfers energy through electromagnetic waves and is the only method that works through empty space, which is how the Sun heats Earth.
Thermal equilibrium: the state when two objects are at the same temperature and no net heat transfer occurs. Conduction: heat transfer through direct particle-to-particle contact; works best in solids. Convection: heat transfer through fluid circulation; warm fluid rises, cool fluid sinks. Radiation: heat transfer through electromagnetic waves; no matter required. Conductor: a material that transfers heat easily (metals). Insulator: a material that resists heat flow (wood, plastic, air, wool).
Energy Transfer Questions
A tile floor and a carpeted floor are in the same room at the same temperature. Why does the tile floor feel colder when you step on it with bare feet?
On a windy day, air is heated near the ground by the Sun. The warm air rises and cooler air rushes in to replace it. Which method of heat transfer creates this wind pattern?
Conduction, convection, and radiation can all transfer heat through a vacuum (empty space).
Which of the following materials are good thermal insulators? (Select all that apply)
Select all that apply.
Match each real-world example to the primary method of heat transfer it demonstrates.