Rates of chemical reactions

What role do catalysts play in chemical reactions?

• Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process.

• Catalysts are substances that decrease the rate of a chemical reaction.

• Catalysts are substances that change the products of a chemical reaction.

• Catalysts are substances that are consumed during the reaction.

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What is surface area in the context of chemical reactions?

• Surface area is the total volume of a solid reactant.

• Surface area refers to the exposed area of a solid reactant.

• Surface area is the temperature at which a reaction occurs.

• Surface area is the mass of the reactants involved in a reaction.

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What is activation energy?

• The energy required to break bonds in the products.

• The minimum energy required for a chemical reaction to occur.

• The energy released during a chemical reaction.

• The energy needed to maintain a chemical reaction.

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NGSS.HS-PS1-5

What is a heterogeneous reaction?

• A reaction that occurs in a single phase, such as a gas reacting with another gas.

• A reaction that involves reactants in different phases, such as a solid reacting with a gas or liquid.

• A reaction that only occurs in aqueous solutions.

• A reaction that produces only solid products.

What happens to the rate of reaction when a solid reactant is cut into smaller pieces?

• The rate of reaction decreases due to less contact between particles.

• Cutting a solid reactant into smaller pieces increases its surface area, which can lead to an increased rate of reaction.

• The rate of reaction remains unchanged regardless of the size of the pieces.

• The rate of reaction becomes unpredictable and varies with each cut.

How does temperature influence the rate of reaction?

• Increasing the temperature decreases the rate of reaction due to less energy for collisions.

• Increasing the temperature generally increases the rate of reaction because it provides more energy to the reactants, leading to more frequent and effective collisions.

• Temperature has no effect on the rate of reaction.

• Higher temperatures slow down the reaction rate by reducing the frequency of collisions.

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NGSS.HS-PS1-5

What is the significance of the coefficients in a chemical equation?

• They represent the physical state of the reactants and products.

• They indicate the relative amounts of reactants and products involved in the reaction.

• They show the temperature at which the reaction occurs.

• They determine the color change during the reaction.

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NGSS.MS-PS1-5

What is a chemical equation?

• A symbolic representation of a chemical reaction, showing the reactants and products along with their quantities.

• A numerical representation of a chemical reaction without any symbols.

• A graphical representation of the physical state of reactants and products.

• A written description of a chemical reaction in everyday language.

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What factors affect the rate of chemical reactions?

• Temperature, concentration of reactants, surface area, and presence of catalysts

• Only temperature and concentration of reactants

• Surface area and temperature only

• Presence of catalysts and pressure only

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NGSS.HS-PS1-5

How does concentration affect the rate of reaction?

• Higher concentration of reactants leads to more frequent collisions between particles, which can increase the rate of reaction.

• Higher concentration of reactants decreases the energy of particles, slowing down the reaction.

• Lower concentration of reactants leads to more frequent collisions, increasing the rate of reaction.

• Concentration has no effect on the rate of reaction.

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NGSS.HS-PS1-5