Chemistry: Final Exam Flashcards
What are examples of ceramics?
- dishes
- pots/pottery
- plates
- china: fancy pots, tea cups
- porcelain: toilet, wash basins
- brick: houses, pizza ovens
- glass: windows, jars, beakers
What are the properties of ceramics? (hint: 6)
- heat resistant
- not deform
- wear resistant
- brittle
- insulators
- electricity resistant
How are ceramics made?
- kiln 1000ºC
- SiO2 (what we need to make sand)
What are polymers?
Long chains of repeating molecules
What is a monomer?
One molecule that can be joined to form a polymer
What is elastic?
tries to return to original shape
What is plastic?
can be reshaped and hold new shape
What are the properties for Natural rubber?
- Soft and sticky when hot
- Hard and brittle when cold
What is Vulcanisation?
- heating rubber with sulphur
- vulcanised rubber is elastic but not plastic because of the heavy, strong cross links
What is Polymerisation?
process by which we make polymer
What is an Exothermic reaction?
- transfers energy to surroundings
- gets hot!
What is an Endothermic reaction?
- energy taken (“consumed”) from surroundings
- gets cold! or requires constant heat
What are Composite materials?
- Combinations of two or more materials, with some of the properties of each
- Many are made by fixing fibres into liquid resin which then sets hard
What is Safety glass?
-shatters and stays together when broken
What are examples of composite materials?
- Concrete
- Paper
- Plywood
What is GRP? (hint: 6)
- Glass-Reinforced Plastic
- Fiberglass
- Lightweight
- Strong
- Semiflexible
- Easily molded into shapes
What is Kevlar and Resin?
- “carbon and fibre”
- strong and lightweight
What is concrete?
- made from a mixture of cement, sand, aggregate (crushed rocks) and water
- very strong
- easily molded
- reinforced with steel rods
What is cement?
- cement is the “glue” for concrete
- cement is lime (calcium oxide of CaO)
What are the problems with materials?
- finite (limited)
- creates harmful compounds by products
What are the harmful compounds?
- Carbon monoxide (CO): caused by incomplete combustion (needs more O2)
- Sulfur dioxide (SO2): caused by sulfur impurities in fuel, forms acid rain
- Nitrogen Oxides (NOx): caused by high temperatures, also forms acid rain
- Carbon dioxide (CO2): a green house gas
What is the word equation for combustion?
C2H6 + O2 -> CO2 + H2O (+CO)-> when insufficient O2
What is Biodegrability?
-ability to break down in nature over time
Why do we need to recycle?
- We know there are finite materials on earth
- We are consuming!
- We will run out
What are landfills?
- ugly; smelly
- occupy land
- dangerous: leaks toxic substances, release gases (CO2, methane -H4- “Greenhouse”)
- expensive to run
What are the ways of recycling?
- Composting
- Paper (recycling)
- Glass (recycling)
- Plastic (re-using)
What are the properties of Metals? (hint:5)
- High melting points
- Good conductors of electricity
- Good conductors of heat
- High density
- Malleable
Properties of asbestos? (hint:5)
- Excellent electrical insulator
- Naturally occurring mineral
- Fire-proof
- Weavable
- Used in construction: roofing, walls, floor tiles
Why are asbestos bad?
- Breathing in fibers through mouth and nose
- They stab the lungs and scar lung tissue
- Leads to lung cancer and other problems
How can we deal with asbestos?
- Seal or cover
- Monitor the air
- Take precaution when demolishing
- Check for it
What are Chlorofuorocarbons (CFC)?
- Used in aerosol spray and refrigerants
- Create holes in the Ozone layer, which protects us from UVC (ultraviolet) radiation from the sun
What is the Ozone layer?
-Ozone layer is “natural sunscreen” from UVC radiation
What are the CFCs elements?
- O2: diatomic oxygen
- O: atomic oxygen
- O3: ozone
What is an explosion?
- It is a chemical reaction that causes a destruction
- exothermic
- releases heat, sound and force-> can destroy or cause mess (shock)
What properties do physical changes have?
- state changes (boiling, melting)
- No new substance
- Easily reversible!
What properties do chemical changes have?
- new products formed
- not easily reversed
What is pressure?
- force exerted upon object
- in gases, causes by collisions
- pressure increases:
- increase temperature-> energy
- increase particles-> increase in collisions!
- decrease volume-> increase collisions
How are explosions in a physical change caused?
- caused by phase change
- rapid expansion of volume
- intermolecular forces are overcome
How are explosions in a chemical change caused?
-Caused by a release of energy in a chemical reaction (breaking and making of bonds)
What is the word equation for Propanes?
C3H8 + O2 -> CO2 + H2O
What does “reactivity” mean?
- “response” to other molecules/elements
- relation between protons and electrons
Memorise:
Metal + Water -> metal hydroxide
Metal + acid -> salt + hydrogen
What are examples of exothermic rxns?
- Sodium hydrogen + hydrochloric acid (neutralisation)
- Methane + Oxygen -> Carbon dioxide + water (combustion of hydrocarbon)
Why does Surface Area malter?
-high S.A increases reaction rate
What does an Oxidizer/ Oxidizing Agent do?
-Provide oxygen for combustion reactions
What is the word equation for Electrolysis?
AI2O3 + C -> no rxn
Characteristics of Electrolysis?
anodes are positively charged
- they attract anions (negative ion)
anthodes are negatively charged
-they attract cations (positive ions)
What is Electrostatic attraction?
-attraction between oppositely changed particles
What is Hydrogen Bonding?
-Electrostatic attraction between the proton (+) of a hydrogen and lone electron pairs (-)
What are Pure Substances?
-all particles are the same
What is a Mixture?
-contains different particles
What is an Element?
-substance made from only one type of atom
What is a Compound?
-substance made from different types of atoms joined together
What are examples of separations techniques?
- Filtration
- Separating Funnel
- Distillation
- Fractional Distillation
