What is the law of conservation of mass and how does it relate to chemical equations?

The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction, and this principle is reflected in balanced chemical equations.

The law of conservation of mass asserts that mass can be created or destroyed in a chemical reaction, and this concept is represented by unbalanced chemical equations.

The law of conservation of mass suggests that mass is only conserved in physical changes, and chemical equations do not adhere to this principle.

The law of conservation of mass is irrelevant to chemical equations as they primarily focus on energy conservation rather than mass conservation.

Why is it necessary to balance a chemical equation?

Balancing a chemical equation ensures that the reactants and products have the same number of atoms of each element, maintaining the law of conservation of mass.

Balancing a chemical equation is optional and does not have any impact on the accuracy of representing chemical reactions.

Balancing a chemical equation is necessary to change the nature of the reaction and make it more energetically favorable.

Balancing a chemical equation is only required for academic purposes and has no practical applications in the field of chemistry.

What role do coefficients play in balancing a chemical equation?

Coefficients in a chemical equation represent the number of molecules of each substance involved in the reaction and are essential for balancing the equation.

Coefficients are used to indicate the state of matter of each substance in the reaction and have no impact on balancing the chemical equation.

Coefficients are arbitrary numbers that can be added to a chemical equation for aesthetic reasons, but they do not affect the accuracy of the representation.

Coefficients are irrelevant to balancing a chemical equation; only the subscripts in the chemical formulas are adjusted to achieve balance.

How is mass conserved when a substance has a physical or chemical change?

Mass is conserved in both physical and chemical changes because the total mass of the reactants equals the total mass of the products.

Mass is not conserved in physical changes, but it is conserved in chemical changes due to the law of conservation of mass.

Mass is conserved in physical changes, but in chemical changes, some mass is lost or gained depending on the reaction.

Mass conservation is a theoretical concept and does not apply practically to either physical or chemical changes in substances.

How is a physical change difference from a chemical change?

In a physical change, the composition of the substance remains the same, while in a chemical change, new substances with different compositions are formed.

A physical change involves a change in color, while a chemical change involves a change in shape.

In a physical change, there is always a release or absorption of energy, while in a chemical change, energy changes do not occur.

A physical change is characterized by the formation of new compounds, while a chemical change only involves alterations in the physical state of matter.

What observable evidence is used to infer that a chemical reaction has occurred?

Change in color, production of a gas, formation of a precipitate, and change in temperature are all observable evidence that a chemical reaction has occurred.

Change in volume, increased pressure, and altered density are indicators that a chemical reaction has taken place.

Any alteration in the physical state, such as melting or freezing, is a clear sign of a chemical reaction.

Changes in odor and alterations in magnetic properties are key indicators that a chemical reaction has occurred.

How does temperature influence a chemical change?

Temperature can affect the rate of a chemical reaction, influencing the speed at which reactants transform into products.

Temperature has no impact on chemical changes; it is solely a factor in physical changes.

Chemical changes occur only at extremely high temperatures, making temperature a critical factor in initiating reactions.

Chemical changes are unaffected by temperature variations, as they are solely dependent on the nature of the substances involved.

In adherence to the law of the conservation of mass, which of the following examples serves as an illustration that mass remains constant and is neither generated nor eliminated in typical chemical reactions?

When carbon dioxide is broken down into carbon and oxygen, the number of atoms remains the same.

When hydrogen and oxygen combine to make water, oxygen atoms are converted to hydrogen atoms.

When sodium and chlorine combine to make salt, some of the sodium is always lost.

When iron reacts with oxygen to form rust, the mass of the iron atoms increases.

Defined as the interaction of chemicals resulting in new substances, a chemical reaction is illustrated. Considering the law of conservation of mass, what is the most logical inference regarding the composition of the missing product in the illustrated reaction?

One oxygen atom and three hydrogen atoms

One oxygen atom and one hydrogen atom

One chlorine atom and two hydrogen atoms

Two chlorine atoms and three hydrogen atoms

Which statement accurately describes the atoms involved in a chemical reaction among the following options?

The same number of each type of atom will always be present before and after a chemical reaction takes place.

Some of the atoms present before the reaction will always be lost during a chemical reaction.

Some of the atoms will always be changed into a different type of atom by a chemical reaction.

During a chemical reaction, atoms will always be combined into much larger molecules.

Which of the following examples presents evidence of a chemical change?

Sugar that is burned gives off an odor and turns brown and then black.

A sample of zinc is placed in water, and it settles to the bottom.

A solid block of ice is heated, and it completely melts into a liquid.

A sample of a mineral is broken down into smaller pieces.

Monica and Andre are examining distinctions between physical and chemical changes, recording their observations in a table. Among the following, which observation did Monica and Andre mistakenly categorize?

Water boils, and steam is produced.

In a glow stick, the light we observe results from a chemical reaction. What action among the following is most likely to reduce the rate of this chemical reaction in the glow stick?

Place the glow stick in a freezer

Shake the glow stick more rapidly

Put the glow stick in hot water

Hold the glow stick close to a light

On his science test, Charlie needs to offer an instance of a physical change. Which of the following would be an accurate answer?

A sample of dry ice is left out, in room temperature, and turns into a gas.

Calcium chloride and baking soda are mixed. and the temperature increases.

Milk curdles are formed when a jug of milk spoils because it is left out of the fridge.

Baking soda and vinegar are mixed together, and bubbles are formed.

The image depicts the outcome when cold-medicine tablets are submerged in room temperature water. What signs would suggest that a chemical change has taken place?

The water level increases slightly.

Shauna is preparing breakfast for her family. At which stage of the breakfast preparation did Shauna witness a chemical change?

When she toasted bread and it turned brown

When she cracked eggs into a bowl and they changed shape

When she poured milk on cereal and it was no longer dry

When she squeezed oranges and the juice came out

In a physical change, what occurs to differentiate it from a chemical change?

The properties of the substance may change, but no new substances are produced

The properties of the substance change for only a short time, but they will return to their original state.

An entirely new substance with new properties forms as a result of the change.

A new substance is produced, but the new substance has properties identical to the original substance.

Four mixtures are created by combining two clear liquids, and observations are conducted. Among these mixtures, which one indicates that a chemical change has taken place?

Mixture 2: The liquids, when mixed, produce a white solid that settles to the bottom.

Mixture 1: The combined liquids have a greater mass than either of the starting liquids.

Mixture 3: The mixture of the two liquids takes the shape of the container.

Mixture 4: The denser of the two liquids lies below the other, less dense liquid.

Law of Conservation of Mass / Physical and Chemical Changes

8th Grade

•

39 Qs

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Law of Conservation of Mass / Physical and Chemical Changes

Quiz

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Science

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8th Grade

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Practice Problem

•

Medium

•

NGSS

MS-PS1-5, MS-PS1-2, MS-PS1-4

Standards-aligned

Austin Ritenour

Used 7+ times

FREE Resource

39 questions

Show all answers

MULTIPLE CHOICE QUESTION

1 min • 1 pt

What is a symbolic representation of a chemical reaction in which both sides of the equation contain equal numbers of atoms of each element?

Balanced Chemical Equation

Chemical Formula

Coefficient

Product

Tags

NGSS.MS-PS1-5

MULTIPLE CHOICE QUESTION

1 min • 1 pt

What are chemical formulas and symbols written to represent a reaction?

Chemical Equation

Chemical Reaction

Law of Conservation of Matter

Reactant

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

MULTIPLE CHOICE QUESTION

1 min • 1 pt

What is a shorthand notation that uses chemical symbols and numbers as subscripts to represent the type and number of atoms that are present in the smallest unit of a substance?

Chemical Formula

Coefficient

Product

Subscript

MULTIPLE CHOICE QUESTION

1 min • 1 pt

What is the process by which one or more substances change to produce one or more different substances?

Chemical Reaction

Law of Conservation of Matter

Reactant

Endothermic Reaction

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

NGSS.MS-PS1-5

MULTIPLE CHOICE QUESTION

1 min • 1 pt

What is a number placed in front of a chemical symbol or formula that represents the number of molecules?

Coefficient

Product

Subscript

Exothermic Reaction

MULTIPLE CHOICE QUESTION

1 min • 1 pt

What is the scientific law stating that the mass of all reactants must equal the mass of all products; matter is neither created nor destroyed?

Law of Conservation of Matter

Reactant

Endothermic Reaction

Precipitate

Tags

NGSS.MS-PS1-5

MULTIPLE CHOICE QUESTION

1 min • 1 pt

What is a substance produced during a chemical reaction?

Product

Subscript

Exothermic Reaction

Balanced Chemical Equation

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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Law of Conservation of Mass / Physical and Chemical Changes

39 questions

What is a symbolic representation of a chemical reaction in which both sides of the equation contain equal numbers of atoms of each element?

What are chemical formulas and symbols written to represent a reaction?

What is a shorthand notation that uses chemical symbols and numbers as subscripts to represent the type and number of atoms that are present in the smallest unit of a substance?

What is the process by which one or more substances change to produce one or more different substances?

What is a number placed in front of a chemical symbol or formula that represents the number of molecules?

What is the scientific law stating that the mass of all reactants must equal the mass of all products; matter is neither created nor destroyed?

What is a substance produced during a chemical reaction?

What is a substance that takes part in and undergoes change during a chemical reaction?

What is a number written below and to the right of a chemical symbol that shows the number of a specific type of atom present?

What is a chemical reaction in which heat is absorbed?

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