Unit 2 - Kinetics Flashcards
Is bond breaking exothermic or endothermic?
Endothermic
Is bond making exothermic or endothermic?
Exothermic
What effect will increasing the surface area of a reactant have on the reaction?
Increase the rate of reaction
what effect will decreasing the temperature of a reaction have on its rate?
It will decrease the rate of reaction
what effect will increasing the concentration of a reactant in solution have on the rate of the reaction
It will increase the rate of the reaction
what effect will decreasing the pressure of a gas reactant have on the rate of its reaction
It will decrease the rate of reaction
what effect will decreasing the surface area of solid reactants have on their rate of reaction
It will decrease their rate of reaction
How do catalyst work and what effect do they have on the rate of a reaction?
Catalysts provide an alternative reaction pathway with a lower activation energy. They speed up the rate of reactions as more particles will have energy greater than or equal to the activation energy
Draw a Maxwell Boltzmann distribution graph of a reaction showing activation energy and activation energy with a catalyst (4 marks)
- Correctly drawn curve
- Correctly labelled x and y axis
- Vertical line showing activation energy (accept Ea)
- Vertical line on the left of activation energy showing activation energy with catalyst (accept Ea cat)
What does the peak of a Maxwell Boltzmann distribution graph show?
The most probable energy of reactant particles
Where would you expect to find the mean energy of a particle on a Maxwell Boltzmann distribution graph?
To the right of the peak
For particles to react, how must they interact with each other? (2 marks)
- They must collide with the minimum activation energy
2. They must collide in the correct orientation
If two reactant particles collide, will they react?
Not necessarily - they must have at least the activation energy and be in the correct orientation
What does the term homogeneous mean when referring to catalysts?
The catalyst is in the same phase (or state) as the reactants
What does the term heterogeneous mean when referring to catalysts?
The catalyst is in a different phase (or state) as the reactants
Draw a curve on a Maxwell Boltzmann distribution graph of a reaction and a second curve showing the same reaction at a higher temperature (3 marks)
- Correctly drawn curves
- Correctly labelled x and y axis
- correctly labelled curves (accept T1 and T2)
Define endothermic
A reaction that takes in energy
Define exothermic
A reaction that gives off energy
State the first law of thermodynamics
Energy can neither be created nor destroyed. It can only change forms
what does the equation q=mCΔT express and what are the units? (4 marks)
Heat energy(J) = mass(g) x specific heat capacity(JgK) x change in temperature(k)
