Question

What name is given to a substance that speeds up the rate of a reaction by decreasing the activation energy needed for the reactants to turn into products? (A) a noble gas (B) a compound (C) an alloy (D) a catalyst

Short answer

The correct answer is (D) a catalyst, as it is a substance that speeds up the rate of a reaction by decreasing the activation energy needed for reactants to turn into products.

Step-by-step solution

Understanding the concept behind the term

The question is asking for the name of a substance that speeds up the rate of a chemical reaction and lowers the activation energy required for the reactants to turn into products. The activation energy is the minimum amount of energy required for a reaction to proceed. By decreasing the activation energy, this substance makes it easier and faster for reactions to occur.

Analyzing given options

Now, let's analyze the given options to see which one fits the description: (A) A noble gas: Noble gases are known for their low reactivity and are generally chemically inert, so they generally do not speed up chemical reactions. (B) A compound: A compound is a generic term for a substance composed of two or more elements chemically bonded together. It may or may not act as an accelerator for some reactions, but it is not specific enough to answer the question. (C) An alloy: An alloy is a substance made up of two or more metals or metalloids mixed together. While some alloys may have catalytic properties, the term 'alloy' does not inherently mean they accelerate reactions. (D) A catalyst: A catalyst is a substance that speeds up the rate of a reaction by lowering the activation energy needed for the reactants to turn into products, without being consumed in the reaction itself. Therefore, this is the correct answer.

Selecting the correct answer

The correct answer is (D) a catalyst, as it is a substance that speeds up the rate of a reaction by decreasing the activation energy needed for reactants to turn into products.

Key concepts

Activation Energy

Activation energy is a fundamental concept in understanding how chemical reactions occur. It is the minimum amount of energy that reactant molecules must possess for a reaction to take place. Without sufficient energy, reactants remain "stuck" without forming any products.
Imagine starting a car; activation energy is like turning the key to spark the engine. Without turning the key, the car remains idle. Similarly, in a chemical reaction, activation energy sets the process in motion.

• It acts as an energy barrier that reactants must overcome to start forming the products.
• Measuring activation energy helps determine the speed and feasibility of a reaction.

Catalysts play an essential role by lowering the activation energy necessary for reactions, allowing them to occur more readily and at a faster pace.

Chemical Reaction

A chemical reaction involves the transformation of substances from reactants to products. During this process, bonds between atoms in the reactants are broken, and new bonds are formed in the products. This change is accompanied by a significant energy transfer.
Chemical reactions are at the heart of various processes, both naturally occurring and industrially important.

• Reactants are the starting materials for a chemical reaction.
• Products are the new substances formed as a result of the reaction.
• Different factors, such as temperature, concentration, and presence of a catalyst, can influence the reaction.

The essence of a chemical reaction lies in the rearrangement of atoms, which leads to the formation of new substances with unique properties.

Reaction Rate

The reaction rate refers to how fast reactants are converted into products during a chemical reaction. It is a measure of the speed at which a reaction occurs and can vary significantly between different reactions.
Understanding reaction rates is crucial, especially in fields like chemical engineering, where efficiency and safety are key.

• The rate can be influenced by factors such as temperature and pressure.
• Increasing the concentration of reactants generally speeds up the reaction rate as it raises the likelihood of collisions between particles.
• A catalyst can dramatically increase the reaction rate by providing an alternative pathway with a lower activation energy.

Controlling the reaction rate allows chemists to optimize conditions for desired outcomes, ensuring that reactions proceed at an appropriate pace to maximize yield and efficiency.