Law of Conservation of Mass

What does a coefficient in a chemical equation represent?

• It represents the type of reaction occurring.

• It indicates the number of molecules or moles of a substance involved in a reaction.

• It shows the temperature at which the reaction occurs.

• It denotes the pressure conditions of the reaction.

What does it mean for a reaction to be exothermic?

• A reaction that absorbs energy from the surroundings.

• A reaction that releases energy, usually in the form of heat.

• A reaction that occurs at a constant temperature.

• A reaction that requires a catalyst to proceed.

What is the difference between a physical change and a chemical change?

• A physical change alters the form of a substance but not its chemical composition, while a chemical change results in the formation of new substances.

• A physical change involves a change in temperature, while a chemical change does not.

• A physical change can be easily reversed, while a chemical change cannot be reversed at all.

• A physical change affects the chemical properties of a substance, while a chemical change does not.

What is an example of a balanced chemical equation?

• H2 + O2 -> H2O

• 2H2 + O2 -> 2H2O

• H2 + O2 -> 2H2O

• 2H2 + O2 -> H2O

What does a subscript in a chemical formula indicate?

• It indicates the type of element present in the molecule.

• It indicates the number of atoms of an element in a molecule.

• It indicates the charge of the molecule.

• It indicates the state of matter of the substance.

What is a reactant in a chemical reaction?

• A substance that is produced during a chemical reaction, found on the right side of a chemical equation.

• A substance that undergoes a change during a chemical reaction, found on the left side of a chemical equation.

• A catalyst that speeds up a chemical reaction without being consumed.

• A mixture of substances that does not undergo any change during a chemical reaction.

How do you determine if a chemical equation is balanced?

• A chemical equation is balanced when the number of atoms of each element is the same on both sides of the equation.

• A chemical equation is balanced when the total mass of reactants equals the total mass of products.

• A chemical equation is balanced when all coefficients are whole numbers.

• A chemical equation is balanced when it contains equal numbers of molecules on both sides.

What is the importance of balancing chemical equations?

• It allows for the creation of new elements.

• It reflects the conservation of mass and ensures that the same amount of each element is present before and after a reaction.

• It simplifies the chemical reaction process.

• It helps in predicting the color changes during a reaction.

What does it mean for a reaction to be endothermic?

• A chemical reaction that releases energy to its surroundings.

• A chemical reaction that absorbs energy from its surroundings.

• A chemical reaction that occurs at a constant temperature.

• A chemical reaction that produces heat.

What is a product in a chemical reaction?

• A substance that is formed as a result of a chemical reaction, found on the right side of a chemical equation.

• A substance that is consumed during a chemical reaction, found on the left side of a chemical equation.

• A catalyst that speeds up the chemical reaction without being consumed.

• A mixture of reactants that does not undergo any change.