Identify Chemical Reactions - Middle School Physical Science
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Which statement best defines a chemical reaction in terms of reactants and products?
Which statement best defines a chemical reaction in terms of reactants and products?
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Reactants form new substances (products) with different properties. Chemical reactions create entirely new materials through atomic rearrangement.
Reactants form new substances (products) with different properties. Chemical reactions create entirely new materials through atomic rearrangement.
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What is the term for the starting substances in a chemical reaction?
What is the term for the starting substances in a chemical reaction?
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Reactants. These are the initial materials that undergo transformation.
Reactants. These are the initial materials that undergo transformation.
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What is the term for the substances formed after a chemical reaction occurs?
What is the term for the substances formed after a chemical reaction occurs?
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Products. These are the new materials created after the reaction completes.
Products. These are the new materials created after the reaction completes.
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Which change is the strongest evidence that a chemical reaction occurred: state change or new substance?
Which change is the strongest evidence that a chemical reaction occurred: state change or new substance?
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New substance formation. State changes are physical; new substances prove chemical change.
New substance formation. State changes are physical; new substances prove chemical change.
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Which observation most directly indicates gas production during a chemical reaction?
Which observation most directly indicates gas production during a chemical reaction?
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Bubbling or fizzing (new gas forms). Gas bubbles show new gaseous products forming.
Bubbling or fizzing (new gas forms). Gas bubbles show new gaseous products forming.
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Which observation most directly indicates precipitate formation in a reaction occurring in solution?
Which observation most directly indicates precipitate formation in a reaction occurring in solution?
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A new solid forms from the liquid (cloudiness/solid appears). Precipitates are new insoluble solids formed in solution.
A new solid forms from the liquid (cloudiness/solid appears). Precipitates are new insoluble solids formed in solution.
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Which observation most directly indicates an energy change during a chemical reaction without heating?
Which observation most directly indicates an energy change during a chemical reaction without heating?
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Temperature changes on its own (warms or cools). Spontaneous temperature change indicates energy release/absorption.
Temperature changes on its own (warms or cools). Spontaneous temperature change indicates energy release/absorption.
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Which option is a chemical change: dissolving sugar in water or burning sugar?
Which option is a chemical change: dissolving sugar in water or burning sugar?
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Burning sugar. Burning breaks sugar molecules into new substances like $CO_2$.
Burning sugar. Burning breaks sugar molecules into new substances like $CO_2$.
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Which option is a physical change, not chemical: melting ice or rusting iron?
Which option is a physical change, not chemical: melting ice or rusting iron?
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Melting ice. Ice melting is just a phase change; same $H_2O$ molecules.
Melting ice. Ice melting is just a phase change; same $H_2O$ molecules.
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Which observation is evidence that a new odor formed, suggesting a chemical reaction occurred?
Which observation is evidence that a new odor formed, suggesting a chemical reaction occurred?
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A new smell appears that was not present before. New odors indicate new molecules with different properties.
A new smell appears that was not present before. New odors indicate new molecules with different properties.
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Which observation is evidence of light being produced as part of a chemical reaction?
Which observation is evidence of light being produced as part of a chemical reaction?
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Light is emitted (glow, flame, spark). Light emission shows energy release from chemical bonds.
Light is emitted (glow, flame, spark). Light emission shows energy release from chemical bonds.
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Identify whether this indicates a chemical reaction: a liquid boils after heating, then cools back to liquid.
Identify whether this indicates a chemical reaction: a liquid boils after heating, then cools back to liquid.
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No chemical reaction (state change only). Boiling/condensing changes phase but not molecular identity.
No chemical reaction (state change only). Boiling/condensing changes phase but not molecular identity.
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Identify whether this indicates a chemical reaction: a clear solution turns cloudy and a solid appears.
Identify whether this indicates a chemical reaction: a clear solution turns cloudy and a solid appears.
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Chemical reaction (precipitate formed). Cloudiness shows insoluble product formation.
Chemical reaction (precipitate formed). Cloudiness shows insoluble product formation.
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Which property comparison is most useful for deciding if products differ from reactants: identity or container shape?
Which property comparison is most useful for deciding if products differ from reactants: identity or container shape?
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Identity (composition/properties), not container shape. Chemical identity reveals if new substances formed.
Identity (composition/properties), not container shape. Chemical identity reveals if new substances formed.
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Which comparison best supports that a reaction occurred: same color before/after or new color appears?
Which comparison best supports that a reaction occurred: same color before/after or new color appears?
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A new color appears (new substance likely formed). Color change often indicates new compounds with different properties.
A new color appears (new substance likely formed). Color change often indicates new compounds with different properties.
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Identify whether this indicates a chemical reaction: a metal is hammered into a new shape with no new material.
Identify whether this indicates a chemical reaction: a metal is hammered into a new shape with no new material.
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No chemical reaction (physical change). Shape change doesn't alter atomic composition.
No chemical reaction (physical change). Shape change doesn't alter atomic composition.
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Identify whether this indicates a chemical reaction: two substances are mixed and the container becomes cold.
Identify whether this indicates a chemical reaction: two substances are mixed and the container becomes cold.
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Chemical reaction (energy absorbed; endothermic). Cold mixture shows endothermic reaction absorbing heat.
Chemical reaction (energy absorbed; endothermic). Cold mixture shows endothermic reaction absorbing heat.
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What is the key particle-level change that distinguishes chemical from physical change?
What is the key particle-level change that distinguishes chemical from physical change?
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Atoms rearrange; chemical bonds break and form. New bonds create new molecules in chemical changes.
Atoms rearrange; chemical bonds break and form. New bonds create new molecules in chemical changes.
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Identify whether this indicates a chemical reaction: vinegar and baking soda produce bubbles immediately.
Identify whether this indicates a chemical reaction: vinegar and baking soda produce bubbles immediately.
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Chemical reaction (gas produced). $CO_2$ gas forms from acid-base neutralization.
Chemical reaction (gas produced). $CO_2$ gas forms from acid-base neutralization.
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Which statement about mass best matches a chemical reaction in a closed system?
Which statement about mass best matches a chemical reaction in a closed system?
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Total mass stays the same (conservation of mass). Atoms rearrange but aren't created or destroyed.
Total mass stays the same (conservation of mass). Atoms rearrange but aren't created or destroyed.
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What is the sign of a chemical reaction when bubbles appear because a new gas is produced?
What is the sign of a chemical reaction when bubbles appear because a new gas is produced?
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Gas production (bubbling). Gas formation indicates new substances with different properties formed.
Gas production (bubbling). Gas formation indicates new substances with different properties formed.
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What is the definition of a chemical reaction in terms of reactants and products?
What is the definition of a chemical reaction in terms of reactants and products?
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Reactants form new substances (products) with different properties. Chemical reactions create entirely new substances with new properties.
Reactants form new substances (products) with different properties. Chemical reactions create entirely new substances with new properties.
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Which term names the starting substances in a chemical change: reactants or products?
Which term names the starting substances in a chemical change: reactants or products?
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Reactants. Starting materials that undergo change in a reaction.
Reactants. Starting materials that undergo change in a reaction.
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Which term names the new substances formed in a chemical change: reactants or products?
Which term names the new substances formed in a chemical change: reactants or products?
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Products. New substances created after a chemical reaction occurs.
Products. New substances created after a chemical reaction occurs.
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What is the key evidence of a chemical reaction when comparing properties of reactants and products?
What is the key evidence of a chemical reaction when comparing properties of reactants and products?
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The products have different properties than the reactants. Chemical reactions always produce substances with new properties.
The products have different properties than the reactants. Chemical reactions always produce substances with new properties.
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