Chapter 6, 8 & 9 + 1 Flashcards
(54 cards)
What is exothermic?
what is endothermic?
Exothermic = Gives off heat, temp increases
Endothermic = Takes in heat, temp decreases
6.1: collision theory: why is a closed system optimal compared to an open system?
A closed system ensures consistent and measurable reaction conditions, making it ideal for accurate experiments, industrial processes, and ensuring maximum efficiency.
In an open system, external factors like airflow, temperature loss, or evaporation can interfere with the optimal conditions for a fast reaction.
This often leads to slower reaction rates compared to a closed system, where conditions are more stable and controlled
6.1: collision theory: what must particles have to successfully collide with one another?
Must collide
Enough energy to overcome activation energy
They must be in the correct orientation.
6.1: collision theory: how can you measure the rates of reactions?
volume of gas produced
mass loss
6.2 effects: what are the effects that effect the rate of reaction?
Surface area of a solid reactant
concentration of reactants
pressure of any gaseous reactants
temperature
presence of a catalyst
6.2 effects: how do you increase rate of reaction?
The frequency of successful collisions- Increasing the no. of collisions that occur over a given time
the proportion of collisions that have energy that is greater to or equal to the Ea by increasing the energy of all collisions.
6.2 effects: What increases the frequency of collisions?
increasing Concentration/ pressure
increasing surface area
6.2 effects: how does increasing concentration or pressure effect the frequency of collisions?
increasing concentration adds more particles to the solution, meaning there is more chances that a collision will occur and therefore a higher chance of successful collisions per unit time.
increasing pressure can be done by adding more particles or decreasing the volume. if the volume is decreased the particles have less space to move around, increasing the chance that particles will collide with one another therefore increasing the chance at successful collisions per unit time.
BOTH OF THESE FACTORS DO NOT EFFECT THE PROPORTION OF SUCCESSFUL COLLISIONS: SIMPLY THAT THERE IS A HIGHER CHANCE.
6.2 effects: How does increasing the surface area effect the frequency of collisions?
By increasing surface area you are increasing the amount of particles that have a chance to react as there are more particles at the surface and therefore the chance of a collision is higher therefore chance of successful collision is greater per unit time.
THIS FACTOR ALSO DOES NOT EFFECT THE PROPORTION OF SUCCESSFUL COLLISIONS
6.2 effects: How do you increase the energy of collisions?
Increasing the temperature
6.2 effects: How does increasing temperature increase the energy of collisions and effect the rate of reaction?
Increasing the temperature increases the speed of particles meaning they collide more frequently. Since the particles are faster there is a higher chance of successful collisions per unit time.
Temperature also increases the average kinetic energy of particle therefore more particles have enough energy to overcome activation energy increasing the proportion of successful collisions.
6.2 effects: Draw a maxwell boltsman distribution for increasing temperature
(check book)
6.3: Catalysts: What role do catalysts play in increasing the rate of specific reactions?
They lower the activation energy a reaction needs to occur this increases the speed of chemical reactions.
6.3: Catalysts: how do catalysts provide an alternative reaction pathway?
lowering the activation energy
6.3: Catalysts: Draw the effect of a catalyst on the energy profile diagram and maxwell-boltzman distribution
(Check book)
6.3: Catalysts: what are the types of catalysts? Which is more useful?
homogenous: A catalyst that is in the same state as the reactants and products
heterogenous: A catalyst that is in a different state to the reactants and products
heterogenous are more useful because they can easily separated from the solution and reused, making them cheaper and more efficient.
8.1: electrolysis: what is Molten and what is aqueous- how do they effect the prediction of electrolysis?
Molten: melted substances
Aqueous: water is present
molten does not effect prediction
aqueous since water is present that has to be included in the predictions
8.1: electrolysis: what is the basic structure of an electrolytic cell? Provide a diagram to support your answer.
Power source
Electrodes
- Anode (+) Positive electrode where oxidation occurs (loss of electrons)
- Cathode (–) Negative electrode where reduction occurs (gain of electrons)
Electrolyte Ionic solution or molten compound that conducts electricity
Wires Connect the power source to the electrodes
8.1: electrolysis: is the reaction spontaneous or non-spontaneous- why/why not?
Non-spontaneous- it has to be forced by electricity to occur, does not react naturally.
8.1: electrolysis: how do you determine what will react?
strongest oxidant (furthest up on the left) vs strongest reductant (furthest down on the right)
8.1: electrolysis: How can the electrochemical series fail?
when the system is not at SLC
when the solutions are not at 1 M concentration
8.1: electrolysis: compare galvanic cells to electrolytic cells
Galvanic:
- produces electricity
- spontaneous
- chem –> electrical
oxidation = anode (-)
reduction = cathode (+)
Electrolytic
uses electricity
- non- spontaneous
- electrical –> chem
oxidation = anode (+)
reduction = cathode (-)
A student sets up an electrolysis experiment using a
cell made of a copper anode, a nickel cathode and a
sodium nitrate solution as the electrolyte.
a-Refer to the electrochemical series and identify
the possible reactions that could occur at each
electrode. Write these half-equations in the order
they appear in the series.
b-Identify the correct half-equations for the reactions
that occur at the anode and cathode.
c-Write an equation for the overall reaction.
a. Possible reactions at the anode (positive electrode):
O2(g) + 4H+(aq) + 4e− –>2H2O(l) +1.23 V
Cu2+(aq) + 2e− –> Cu(s) +0.34 V
Na+(aq) + e− –> Na(s) −2.71 V
Possible reactions at the cathode (negative electrode):
Ni2+ (aq) + 2e− –> Ni(s) −0.25 V
2H2O(l) + 2e− –> H2(g) + 2OH−(aq) -0.83V
Na+(aq) + e− –> Na(s) −2.71 V
b anode: Cu(s) l Cu2+(aq) + 2e−
cathode: 2H2O(l) + 2e− l H2(g) + 2OH−(aq)
c Cu(s) + 2H2O(l) l Cu2+(aq) + 2OH(aq) + H2(g)
8.2: what are the common design features and general operations of electrolysis- where practical the removal of products as they form?
Electrolytic cells, used in electrolysis, typically consist of an electrolyte, two electrodes (anode and cathode), and a power source. The process involves using electrical energy to drive a non-spontaneous redox reaction, where ions in the electrolyte move towards the oppositely charged electrodes. In many cases, products formed at the electrodes can be removed as they form, either by collecting gases or precipitating solids
