Chemistry: Conditions Affecting Chemical Reactions Flashcards
What is Le Chateliers principle?
equilibrium is disturbed by changing conditions
Describe how pressure will affect chemical reactions
Affects reactions INVOLVING GASES:
↑pressure = favors side with ↓mols
↓ pressure = favors side with ↑mols
If you increase pressure in this reaction, what side will the reaction favor?
A (g) + 2Br (g) ⇌ C (g) + D (g)
Reactants side: 3 mols total
Products side: 2 mols total
Since this is a problem involving gases, increasing pressure will favor the side with FEWER mols; therefore, we are favoring the product side/forward reaction
How does an increase/decrease in temperature affect which side of the reaction it will favor?
↑ temp = favors endothermic rxn
↓ temp = favors exothermic rxn
By looking at an equation, how can you tell if it is a exothermic reaction?
Exothermic rxn will have +heat in the products side
If temperature is decreased, which way will the rxn move/favor?
CO + 3H₂ ⇌ CH₄ + H₂O + Heat
If you decrease heat, you are no long in equilibrium, so to get back, you would need to add heat. This means the rxn would favor the products side.
Increasing the reactants will favor the ______ reaction/_____ side
forward/products
Increasing the products will favor the ______ reaction/_____ side
reverse/reactant
Decreasing the reactants will favor the ______ reaction/_____ side
reverse/reactants
Decreasing the products will favor the ______ reaction/_____ side
forward/products
The physical state of reactants can affect a chemical reaction. Decrible how this can be
Solids are harder to react because the molecules in the solids are in solid form and are fixed
Liquids and solids have an easier time reacting because the molecules are more “free” and are “moving”
T/F: A catalyst will increase the reaction rate for the forward and reverse reaction, but in different amounts
False, a catalst will increase the rate of the forward and reverse rxn in the SAME amount
For the reaction CaO(s) + H2O(l) ⇋ 2CO(g) + heat, the rate of the forward reaction will be favored (increase) under which of the following conditions?
A) CaO is removed
B) H2O is removed
C) Decrease the temperature
D) CO is added
C, decreasing the temperature means that we are no longer in equilibrium. To fix this, we would need to produce more heat, therfore, the forward reaction will be favored.
A: If CaO is removed, we would need to make more CaO to return to equilibrium, which would favor the reverse rxn
B: If H2O is removed, we would need to make more H2O to return to equilibrium, which would favor the reverse rxn
D: If CO is added, then we now have too much CO and are not in equilibrium, so we would need to use up CO a, which would favor the reverse reaction
For the reaction 2SO2(g) + O2(g) ⇋ 2SO3(g), equilibrium would favor the reactant side if which of the following occurs?
A) Adding O2
B) Removing 2SO3
C) Decreasing the pressure
D) Adding SO2
C, when pressure is decreased, the reaction will move toward the side with more moles of gas. On the left side, there are 3 moles of gas (2 from SO2 and 1 from O2). On the right side, there are 2 moles of gas (2 from O3).
Which of the following methods can speed up the rate of a chemical reaction?
A) Decreasing temperature
B) Decreasing the concentration of reactants
C) Increasing the concentration of products
D) Increasing the surface area of reactants
D, breaking a solid reactant into smaller pieces or using a powdered form increases its surface area, allowing more particles to be exposed and available for collisions. This increases the frequency of collisions between reactant particles, thereby speeding up the reaction.
