Endo or Exo
A reaction absorbs heat from its surroundings and its temperature drops. Endothermic or exothermic?
Endothermic; the system absorbs heat from the surroundings.
Name one factor that can increase the rate of a chemical reaction
Any of the following: temperature, concentration, surface area, catalyst, pressure (for gases), stirring.
If a reaction suddenly speeds up after adding more reactant A, what simple explanation fits this observation?
More collisions per time.
For a reversible reaction that is at equilibrium, what happens if you add more reactant?
Shifts right.
When mixing two solutions releases heat that you can feel on the outside of the container. Endothermic or Exothermic?
Exothermic; the surroundings absorb heat from the system.
How does increasing temperature generally affect reaction rate?
Increases rate.
What type of change increases mixing and contact beween reactants?
Stirring.
If a system at equilibrium is cooled and the forward reaction is exothermic, predict the shift of equilibrium.
Shift right.
A chemical reaction converts potential energy stored in bonds into thermal energy in the surroundings. Endothermic or exothermic?
Exothermic; energy leaves chemical bonds as heat to surroundings.
Does increasing surface area of a solid reactant increase or decrease reaction rate?
Increases rate.
A student halves the concentration of one reactant and notices the reaction slows down. What happened?
Fewer effective collisions per time.
A sealed container at equilibrium has some product removed continuously. How will the equilibrium shift?
Shift right.
A student places a cold pack on their ankle; the pack becomes cold when activated. Endothermic or Exothermic?
Endothermic; it absorbs heat from surroundings causing a cooling sensation.
How does a catalyst affects activation energy and reaction rate?
Decreases activation energy, increases rate.
The addition of what type of gas does not affect reaction rate?
Inert gas.
For the equilibrium N2(g) + 3 H2(g) ⇌ 2 NH3(g), how will equilibrium shift if the volume is decreased?
Shift right
A system has a negative enthalpy change (ΔH < 0). Endothermic or exothermic?
Exothermic (ΔH < 0); negative ΔH means heat released to surroundings.
Excluding temperature changes, how can effective collision frequency be increased?
Increase concentration or increase surface area.
What does a catalyst do to reaction rate?
Lowers activation energy and speeds up reaction rate.
In a reversible reaction where heat behaves like a product, how will equilibrium shift when you remove heat?
Shift right