Unit 3 - Chemistry in Society Flashcards
Simple distillation steps
- Place the liquid and dissolved solid into the flask
- Evaporate the liquid by heating
- Use a thermometer blocking the top of the tube to monitor the temperature
- Direct the vapour down a side pipe with a condenser
- Use running tap water flowing through the condenser
- Collect the condensed liquid in a beaker
- Left with solid crystals in the flask and liquid in the beaker
Factors influencing sustainable industrial process design
- availability
- sustainability
- cost
- opportunities for recycling
- energy requirements
- marketability of biproducts
- product yeild
Environment considerations for industrial process design
- minimizing waste
- avoiding toxic substances
- biodegradable products
Feedstock availability sustainability and cost profit gain and loss
Gain - local availability
Loss - scarcity, transport- safety, cost, environmental
Opportunities for recycling in industrial processes profit gain and loss
Gain - efficiency^, reduce waste
Loss - difficulty separating unreacted stuff makes it inefficient
Energy requirements and Industrial processes profits gain and loss
Gain - exothermic reactions to keep heat in reaction, or even building; catalysts
Loss - reactions needing heat or cooling can be expensive
Use of byproducts in industrial processes profits gain and loss
Gain - selling biproducts or using elsewhere in a process
Loss - toxic biproducts difficult
Product yield in industrial processes profit gain and loss
Gain - high yield is profitable
Loss - low yields need more expensive repetition of reaction
For n=cV volume must be in
LITRES
Mv
V/m
Volume per mole
Relative rate equation
Rate = 1/time
Time from relative rate
Time = 1/relative rate
Collision theory requirements for a reaction
- correct collision geometry
- sufficient energy to reach an activated complex
Effects on rate
- concentration/ pressure
- particle size
- temperature
Energy distribution diagram for lower energy complex
Y axis = no. of molecules
X axis = kinetic energy
Steeper rising limb, peaks sooner and higher, smaller section past the E(A) line
Energy distribution diagram for higher energy complex
Y axis = no. of molecules
X axis = kinetic energy
More gentle rising limb, peaks later, greater section past the E(A) line
Temperature is
The measure of the average kinetic energy of the particles in a substance
The activation energy is
The minimum kinetic energy required by colliding particles before a reaction may occur
Changing concentration, pressure or particle size impacts the reaction rate because
The number of collisions are increased
Change in temperature effects the reaction rate because
Reacting particles have sufficient energy
In an exothermic reaction the products have ____ energy than the reactants because
Less, energy is being released to the surroundings
In the endothermic reaction the enthalpy change is ______ because
Positive, the reactantion gains energy from its surroundings
ΔH =
H(products) - H(reactants)
The activated complex is
A high energy, unstable arrangement of atoms
Increasing temperature does not affect the activation energy, whereas ______ do
Catalysts
The enthalpy of combustion is
The enthalpy change when one mole of a substance is burned completely in oxygen
Apparatus to measure the enthalpy of combustion
Copper can, thermometer, water, all above the combusting fuel and surrounded by draft shield
The enthalpy of combustion will always be
Negative, and in kJ mol¯¹
When using cm³ water measurements in enthalpy change calculations
Remember to convert to kilograms
Hess’s law
The enthalpy change of a chemical reaction is independent of the route taken
When calculating Bond enthalpies, remember breaking bonds
Requires energy
When calculating Bond enthalpies remember
Making bonds releases energy
Molar bond enthalpy is
The energy requires to break one mole of bonds in a diatomic molecule
Equilibrium is where
The rate of the forward reaction equals the rate of the backwards reaction
Concentrations of reactants and products at equilibrium are _______ but rarely _______
Constant, equal
How do catalysts impact equilibrium
They don’t move the equilibrium but may increase the speed at which it is reached
Effect of addition of an alkali on equilibrium when the product includes H+ ions
Right, as the the alkali removes H+ ions and the forwards reaction will replace them
If you increase pressure the equilibrium will shift to____
Get rid of whichever side has more mols of gas
If the forward reaction is exothermic then an increase in temperature will..
Favour the backwards reaction, equilibrium shifts left
Chromatography is used to
Separate components within a mixture
Effects on chromatography results
- Polarity - solubility in p/np solvent
- Molecular size
Type of chromatography results
Distance or time against response graph
Concordant titre volumes
0.2cm³
Titration not requiring an indicator
Acidified permanganate, since it already goes purple to colourless
Titration is used to determine
The volume of a solution required to reach the end point of a reaction
Phenolphlaline colour change
Adic - colourless
Basic - pink
Standard solutions
Solutions of accurately known concentration
