Flashcards in C2 - Chemical Resources Deck (53)
What is the lithosphere?
The crust and upper part of the mantle.
How can we use seismic waves to understand the structure of the Earth?
- S-waves can travel through the mantle, which shows that it's solid. S-waves can only travel through solids.
- S-waves not detected in outer core's shadow, suggesting is is liquid.
- P-waves travel faster through the middle of the core, suggesting the inner core is solid.
Describe the evidence found that proves continental drift theory.
- Mid-Atlantic Ridge discovered.
- Evidence found of magma rising up from sea bed.
- Creatures with same genetic history found on multiple continents.
Explain how two plates can collide and cause a volcanic eruption?
- Crust on the ocean floor is denser than the crust below the continents.
- The dense oceanic plate is forced (subducted) underneath the less dense continental plate.
- These regions are generally cooler and therefore more dense, so they sink really easily.
- As the oceanic plate is forced down, it melts and the molten rock starts to rise.
What are igneous rocks?
They are rocks made when any sort of molten rock cools down and solidify.
Explain how the rate of cooling effects the crystallization of igneous rocks.
If the molten rock cools over a longer period of time, the crystals on the igenous rock will larger and more defined - this is because the interlocking crystal structure will have had longer to form.
On the other hand, fast-cooling molten rock will generally become igneous rocks with smaller crystals.
What igneous rock is produced from runny lava from fairly safe eruptions?
What igneous rock is produced from thick, viscous lava released from explosive eruptions?
Explain the formation of sedimentary rock.
1. Layers of sediment are deposited in lakes or seas.
2. Over millions of years, these layers are buried under the weight of more layers of material. This weight squeezes the water from inside the sedimentary layers.
3. Fluids flowing through the pores deposit natural mineral cement.
What is the symbol equation for the thermal decomposition of limestone?
CaCO3 -> CaO + CO2
Explain the formation of metamorphic rocks.
1. Formed from the action of heat and pressure on other rocks over long period of time.
2. As long as rocks don't melt, they're considered metamorphic.
Give an example of a metamorphic rock and explain its properties.
- Just another form of calcium carbonate.
- Heat and pressure break down the limestone and it reforms as small crystals.
- As a result, the marble is much harder.
Name an igneous rock and explain its properties.
- Various minerals randomly arranged in a structure of interlocking crystals.
- As a result, granite is very hard.
How is glass made?
Limestone is heated up with sand (silicon dioxide) and soda (sodium carbonate) until it melts.
When the mixture cools, it comes out as glass.
How does clay form?
Formed from weathered and decomposed rocks.
How do we make bricks?
Bricks are hardened forms of clay.
We put clay under very high temperatures, hardening them - as a result, bricks can withstand lots of weight (great for stacking).
How do we make cement?
- Limestone and clay heated together.
- Water slowly reacts with cement, making it harden gradually.
Why is reinforced concrete stronger than ordinary concrete?
Steel rods are inserted into the concrete, combining the hardness of the concrete with the strength (tensile strength) and flexibility of steel.
What is a composite material?
A combination of two materials.
Explain how electrolysis is used to purify copper.
- An impure positive annode and a pure negative cathode.
- In a solution (the electrolyte) of copper (II) sulfate, containing lots of Cu^2+ ions.
- Electrons pulled off from the copper atoms at the anode, leaving positive Cu^2+ copper ions in the solution.
- These positive ions are attracted to the negative cathode. They offer their electrons to the cathode, turning the Cu^2+ ions back into copper atoms that are then deposited at the cathode.
- Impurities dropped at the anode as sludge.
What process happens at the cathode? What is the ionic half equation?
Reduction (gain of electrons):
Cu2+ + 2e– → Cu
What process happens at the anode? What is the ionic half equation?
Cu → Cu^2+ + 2e-
What is an alloy?
A mixture of a metal and other elements.
- A metal and metal
- A metal and a non-metal
What is steel? What are its advantages
Steel is an alloy of iron and carbon. This is an advantage as steel is a lot harder than iron and less likely to rust than iron on its own.
What is solder?
An alloy of lead and tin.
What is amalgam?
An alloy of mercury, used in dentistry for filling teeth.
What is brass?
An alloy of copper and zinc, used in musical instruments.
Describe the features of a specific smart alloy.
Nitinol is a smart alloy that has shape memory. It can be bent and twisted before turning back to its original shape.
Compare the properties of iron and aluminium.
- Iron is more dense than aluminium.
- Iron is magnetic, aluminium is not.
- Iron corrodes (rusts) easily and aluminium does not.
- Iron and aluminium are both malleable.
- Iron and aluminium are both good conductors.