A substance that increases the rate of a chemical reaction by providing an alternative pathway with lower activation energy, without being permanently consumed or chemically.
A helper that makes the reaction easier but isn't used up in the process.
Showing a random 20 of 50 problems.
Example 1
hard
For N2โ+3H2โโ2NH3โ (ฮH<0), explain why a catalyst alone does not raise yield, but adjusting T and P can.
Example 2
challenge
A student claims a catalyst could be used to convert graphite into diamond at room temperature. Why is this false?
Example 3
easy
How does a catalyst speed up a reaction?
Example 4
medium
A homogeneous catalyst is in the ____ phase as the reactants, while a heterogeneous catalyst is in a ____ phase.
Example 5
easy
Does a catalyst shift the position of equilibrium?
Example 6
easy
In the decomposition of hydrogen peroxide, MnO2โ acts as a catalyst: 2H2โO2โMnO2โโ2H2โO+O2โ. Explain the role of MnO2โ.
Example 7
medium
Why is a powdered catalyst usually more effective than the same mass in a single lump?
Example 8
challenge
In 2SO2โ+O2โโ2SO3โ with a V2โO5โ catalyst, explain what the catalyst does and does not change about this equilibrium.
Example 9
easy
Which of these does a catalyst change: rate, ฮH, equilibrium position, Eaโ?
Example 10
easy
Does a catalyst change the rate of the forward reaction, the reverse reaction, or both?
Example 11
medium
Sketch (describe) the reaction profile of an exothermic reaction with and without a catalyst, labeling Eaโ, Eaโฒโ, ฮH.
Example 12
medium
A catalyst lowers Eaโ from 100 kJ to 75 kJ. The reaction has ฮH=โ40 kJ. What is Eaโ for the reverse reaction with the catalyst present?
Example 13
medium
Explain the difference between a homogeneous catalyst and a heterogeneous catalyst. Give one example of each.
Example 14
medium
A substance speeds up a reaction and is fully recovered afterward. Is it a reactant or catalyst? Justify.
Example 15
medium
A catalyst is added to a reaction and the reaction finishes faster. What changes, and what does not change about the reaction?
Example 16
medium
A catalyst participates in intermediate steps. How can it still be 'not consumed'?
Example 17
medium
An industrial process uses iron as a catalyst for ammonia synthesis. Why is the iron not listed as a reactant?
Example 18
medium
A reaction has Eaโ=80 kJ. With a catalyst, Eaโฒโ=60 kJ. At 300 K, by what factor does the rate increase? (Use kโeโEaโ/RT, R=8.314ย J/(mol\cdotpK).)
Example 19
challenge
A student claims that because a catalyst appears in the mechanism, it must be either a reactant or a product. Refute this.
Example 20
easy
Name the catalyst commonly written above the arrow in the Haber process: N2โ+3H2โโ2NH3โ.