Catalysts Practice Questions

Correct answer: By lowering the activation energy

A catalyst provides an alternative pathway for the reaction with lower activation energy. This allows more reacting particles to form products successfully.

Correct answer: It changes the reaction rate but is not used up

A catalyst affects the speed of a reaction but is not permanently used up. It may take part temporarily, but it is regenerated by the end of the reaction.

Correct answer: Enzyme

Enzymes are biological catalysts found in living organisms. They speed up biochemical reactions such as digestion and respiration.

Correct answer: Amylase

Amylase is an enzyme that breaks down starch into simpler sugars. It is found in saliva and pancreatic juice.

Correct answer: Manganese dioxide

Manganese dioxide speeds up the decomposition of hydrogen peroxide into water and oxygen. It remains chemically unchanged after the reaction.

Correct answer: A catalyst

Manganese dioxide increases the rate of hydrogen peroxide decomposition. It does not get consumed as a reactant in the overall reaction.

Correct answer: Inhibitor

An inhibitor is a substance that slows down or prevents a chemical reaction. It is sometimes called a negative catalyst in simple chemistry contexts.

Correct answer: Iron catalyst

Finely divided iron is used as the catalyst in the Haber process to manufacture ammonia from nitrogen and hydrogen. Its large surface area speeds up the reaction, allowing it to proceed faster under industrial conditions.

Correct answer: Nickel

Nickel is commonly used as a catalyst in the hydrogenation of vegetable oils. This process adds hydrogen to unsaturated oils and can convert them into semi-solid fats.

Correct answer: To convert harmful exhaust gases into less harmful gases

Catalytic converters use metals such as platinum, palladium, and rhodium as catalysts. They help convert harmful gases like carbon monoxide and nitrogen oxides into less harmful substances.

Correct answer: Carbon monoxide

Carbon monoxide is a poisonous gas present in vehicle exhaust. In a catalytic converter, it is oxidized to carbon dioxide, which is less immediately toxic.

Correct answer: The minimum energy needed for a reaction to start

Activation energy is the minimum energy needed for reactant particles to react. Catalysts increase reaction rate by lowering this energy barrier.

Correct answer: They can make reactions faster and more economical

Catalysts help reactions occur faster and often at lower temperatures or pressures. This saves time, energy, and cost in industrial processes.

Correct answer: It is usually chemically unchanged

A catalyst is not consumed in the overall reaction. Its chemical nature and amount usually remain unchanged after the reaction is complete.

Correct answer: Vanadium pentoxide

Vanadium pentoxide is used as a catalyst in the Contact process. It helps convert sulfur dioxide into sulfur trioxide efficiently.

Correct answer: Saliva helping digest starch

Saliva contains the enzyme amylase, which begins the digestion of starch in the mouth. This is an example of biological catalysis.

Correct answer: It speeds up both forward and backward reactions equally

A catalyst speeds up both the forward and reverse reactions. It helps equilibrium be reached faster but does not change the final equilibrium position.

Correct answer: Catalyst poisoning

Poisoning occurs when impurities stick to a catalyst's surface and block its active sites, preventing reactant molecules from binding there. This reduces the catalyst's ability to speed up the reaction, sometimes permanently.

Correct answer: Because it is regenerated and used again

A catalyst is not used up in the overall reaction and can participate repeatedly. Therefore, even a small amount can affect a large amount of reactants.