All flashcards
Flashcard 1: What measurement is most often used as evidence that matter is conserved in an investigation?
Answer: Mass (measured with a balance). Mass directly measures the amount of matter present.
Flashcard 2: What conclusion is supported if a sealed bag has mass 50 g before and 50 g after mixing?
Answer: Matter was conserved in the closed system. Equal masses before and after prove no matter was lost or gained.
Flashcard 3: What does it mean to say matter is conserved during a physical or chemical change?
Answer: Total mass stays the same; matter is not created or destroyed. Matter cannot be created or destroyed, only transformed.
Flashcard 4: Which option is a chemical change: dissolving sugar or rusting iron?
Answer: Rusting iron. Chemical changes create new substances with different properties.
Flashcard 5: What is the expected mass change in a closed system after a change if matter is conserved?
Answer: No change; initial mass equals final mass. Conservation means total mass remains constant.
Flashcard 6: Identify the best tool to measure mass before and after a change to test conservation of matter.
Answer: A balance (such as a digital scale). Balances precisely measure mass in grams or kilograms.
Flashcard 7: What does it indicate if the mass decreases in an open system during a change that makes a gas?
Answer: Matter likely escaped the system (gas left). Open systems allow gases to escape, reducing total mass.
Flashcard 8: What does it indicate if the mass increases in an open system during a change?
Answer: Matter likely entered the system (for example, gas from air). Open systems allow matter exchange with surroundings.
Flashcard 9: Which statement best distinguishes a closed system from an open system in mass investigations?
Answer: Closed: no matter enters or leaves; open: matter can enter or leave. Key difference is whether matter can cross system boundaries.
Flashcard 10: Which option is a physical change: melting ice or burning paper?
Answer: Melting ice. Physical changes alter form but not chemical composition.
Flashcard 11: Choose the correct comparison for conservation of matter: mbefore mafter in a closed system.
Answer: mbefore=mafter. Conservation requires mass equality before and after changes.
Flashcard 12: What should be included in the mass measurement when testing conservation in a sealed bag reaction?
Answer: All contents plus the container (bag) each time. Container mass must be included for accurate total measurement.
Flashcard 13: Which option is the best way to prevent loss of matter when heating causes evaporation?
Answer: Use a covered or sealed container to keep vapor inside. Sealing prevents water vapor from escaping during heating.
Flashcard 14: Identify the best evidence statement for conservation: “The mass was the same before and after in a sealed bag.”
Answer: Equal mass before and after in a closed system supports conservation of matter. This directly demonstrates the law of conservation of matter.
Flashcard 15: Find the final mass: In a closed system, initial mass is 150 g. What is the final mass?
Answer: 150 g. Closed systems maintain constant mass throughout any change.
Flashcard 16: What total mass should be measured after combining 30 g and 45 g in a sealed container?
Answer: 75 g. Add masses: 30 g+45 g=75 g total.
Flashcard 17: Choose the correct conclusion: A sealed flask is 200 g before and 201 g after. What is most likely?
Answer: Measurement error; mass should stay constant in a closed system. Small differences suggest scale precision limits, not actual change.
Flashcard 18: Identify the best claim if mass changes from 80 g to 76 g in an open cup during bubbling.
Answer: Matter escaped as gas; the system was open. Mass decrease indicates gas bubbles escaped the open container.
Flashcard 19: What is the mass change if a closed container is 120 g before and 120 g after a reaction?
Answer: 0 g. Subtract: 120 g−120 g=0 g change.
Flashcard 20: Which system must be used to show conservation of matter when a gas might be produced?
Answer: A closed system (sealed container). Prevents gas from escaping, ensuring all matter stays inside.
Flashcard 21: What measurement is most commonly used as evidence that matter is conserved?
Answer: Mass (often measured in grams). Mass directly measures the amount of matter present.
Flashcard 22: Which type of system must be used to accurately show mass conservation when gas may form?
Answer: A closed system (sealed container). Sealing prevents gas from escaping, ensuring accurate measurements.
Flashcard 23: What does it mean if the mass before and after a change is equal in a closed system?
Answer: Matter was conserved during the change. Equal mass before and after proves no matter was lost or gained.
Flashcard 24: What is the law of conservation of matter during a physical or chemical change?
Answer: Matter is not created or destroyed; total mass stays the same. This fundamental law applies to all physical and chemical changes.
Flashcard 25: Calculate the final mass if mbefore=125 g in a sealed container.
Answer: 125 g. In sealed containers, mass remains constant during changes.
Flashcard 26: Which tool is most appropriate to measure mass accurately in a conservation-of-matter lab?
Answer: A balance or scale. These instruments precisely measure mass in grams.
Flashcard 27: Identify the correct claim: dissolving changes total mass, or it keeps total mass the same?
Answer: It keeps total mass the same in a closed system. Dissolved substances still contribute to total mass.
Flashcard 28: What is the correct conclusion if measured mass increases in an open system during a reaction?
Answer: Matter likely entered (often oxygen from air). Mass gain in open systems indicates matter entered from outside.
Flashcard 29: Decide if matter was conserved: mbefore=50 g and mafter=50 g in a sealed bag.
Answer: Yes, matter was conserved. Equal masses before and after confirm conservation.
Flashcard 30: What is the correct conclusion if measured mass decreases in an open system during a reaction?
Answer: Matter likely escaped (often as a gas). Mass loss in open systems indicates matter left the system.