C6 Rates Flashcards
how do you calculate the rate of reaction?
amount of product produced ÷ time taken
how do you find the reaction rate from graph?
gradient
describe and explain how a graph of reaction rate would look like (3)
- steepest gradient = fast:
high concentration of reactants/abundance of particles → more frequent + successful collision - less steep gradient = slow down:
reactants getting used up → less collision - flat gradient = stops:
all reactants used up
We can measure the rate of a reaction by measuring…?
- LOSS OF MASS in certain time (gas escapes)
- collect + measure GAS PRODUCT in certain time
- TIME how long for solution to turn cloudy
how do you collect + measure GAS PRODUCT?
use a labeled diagrams to explain (there are two ways)
how do you measure LOSS OF MASS?
use a labeled diagram to explain
what conditions (in terms of PARTICLES) are needed for a reaction to take place?
particles COLLIDE + have ENOUGH ACTIVATION ENERGY
how do you make a reaction FASTER? (4)
TEMP. → move faster + more energy → more frequent + successful collision
CONCENTRATION → more particles → more frequent collision → more chance for successful collision
CATALYST → lower Ea → more particles have enough Ea → more successful collision
SA
more particle exposed → more frequent collisions → more chance for successful collision
what do CATALYSTS do?
lower Ea → rxn can occur at lower temp → speed up rxn
do catalysts get used up?
no
what are the environmental benefits of using catalysts?
- saves energy (lower Ea)
* reduces CO2 output
composition of air
78% N2
21% O2
1% CO2, argon, water vapor…
what are some common AIR POLLUTANTS?
what are their SOURCES and EFFECTS?
CO
- incomplete combustion of fossil fuel
- poisonous, displaces O2 in blood
NO
- very hot environment (eg. car engines)
- acid rain
SO2
- combustion of fossil fuels that contain sulfur (eg. coal, oil, gas)
- acid rain
how do you reduce SO2 emission?
- low sulfur petrol
* desulfurization by CaO
how do you reduce CO and NO emission from car exhaust?
catalytic converters
• CO + O₂ → CO₂
•NO + CO → N₂ + CO₂
why do catalysts in catalytic converters need to be replaced if they aren’t used up?
transition metals in converter react with lead → prevents contact of exhaust with converter
what are NITROGEN fertilizers for?
protein → growth
what are POTASSIUM fertilizers for?
photosynthesis → growth
why is ammonia important in agriculture?
NH4NO3 fertilizer
how does HABER PROCESS yield ammonia?
- equation
- conditions for optimum yield
- where to get reactants
3H₂ + N₂ → 2NH₃
(balanced equation shows 3:1 ratio)
conditions:
400-450˚C, 200 atm, iron catalyst
reactants:
N2 from air
H2 from natural gas (eg.methane)
HABER PROCESS:
why does lower temp give a higher yield of ammonia?
what is the drawback of low temp?
+ exothermic rxn → equilibrium towards RHS
- low temp means slower rate of rxn
HABER PROCESS:
why does higher pressure give a higher yield of ammonia?
what is the drawback of high pressure?
+ equilibrium towards RHS (fewer moles)
- expensive
what does the CONTACT PROCESS do?
sulfur (S) → sulfuric acid (H2SO4)
in the presence of catalyst
what are the 4 steps of CONTACT PROCESS?
describe + equation
Sulfur is burnt in oxygen
S + O₂ → SO₂
Sulfur dioxide passes over catalyst (V₂O₅) in air
SO₂ + O₂ → SO₃
Sulfur trioxide dissolved in concentrated sulfuric acid
SO₃ + H₂SO₄ → H₂S₂O₇ (oleum)
Water added to oleum to make concentrated sulfuric acid
H₂S₂O₇ + H₂O → H₂SO₄
