1.2 Rocks And Building Materials Flashcards
Limestone
Calcium carbonate, CaCO3: very important natural chemical material.
Can be used as an abrasive for toothpastes, calcium additive in bread making and as a building material.
Limestone reaction cycle:
Calcium carbonate 👉(heat) calcium oxide + carbon dioxide
CaCO3 (s) 👉 CaO (s) + CO2 (g)
Calcium oxide(quick lime) + water👉 calcium hydroxide (slaked lime) CaO (s) + H2O (l) 👉 Ca(OH)2 (s)
Calcium hydroxide solution + carbon dioxide👉 calcium carbonate + water
Ca(OH)2 (aq) + CO2 (g) 👉 CaCO3 (s) + H2O (l)
When carbon dioxide is bubbled through calcium hydroxide solution what happens?
Solution turns cloudy because a white precipitate has formed, insoluble CaCO3.
Calcium hydroxide is an alkali so turner universal indicator…
Dark blue
Why does the surface of the limestone crumble slightly when in the heat?
Because the limestone has decomposed and a new substance has formed.
Thermal decomposition reaction
When a substance breaks down into two or more new substances when heated strongly.
What type of reaction is it when water is added to calcium oxide?
Exothermic as heat is given out.
What other test could calcium hydroxide be used for?
To test for carbon dioxide.
Acid + (metal)carbonate=
Carbon dioxide + (metal)salt+ water
Carbonates are bases so means they neutralise acids.
What is suck back?
When you remove the heat from the apparatus, the air and gas vapours inside will contract when they cool, potentially creating a vacuum.
If the bottom-end of the delivery tube was below the liquid surface then it could literally suck back some of that liquid into the apparatus.
Metal carbonate 👉(heat)
Metal oxide + carbon dioxide
When heating, if the metal in the carbonate is less reactive…
The carbonate decomposes more easily.
Sulfate
SO4
Nitrate
NO3
What is carbon dioxide?
A green house gas, these gases trap heat therefore warming the earth causing global warming.
Limestone + clay👉
Portland cement
Cement + sand+(water)👉
Mortar
Cement + sand + aggregate + (water) 👉
Concrete
What happens when you breath in cement?
It will start to react with moisture in lungs.
Cement is made in industry by…
Heating limestone with clay.
What is the relationship between breaking mass and mass of aggregate in concrete?
As the mass of the aggregate increases the breaking point increases to a maximum point and then decreases.
What does taking an average do?
Reduces the effect of random errors.
Why might a reactive solid be cooled in a dry, argon environment?
Argon- noble, stable gas…not very reactive.
Dry- not react with water or carbon dioxide.
Advantages of a building/ extending a limestone quarry?
Can just extend Open up more jobs Good place- can get to in England easily Supports some local businesses Will wash wheels and clean lorries Jobs safeguarded for 20 years More limestone production Will be restored at end
