Chemical World Flashcards
What is the chemical name for limestone?
calcium carbonate.
What is the limestone cycle?
Calcium carbonate-calcium oxide- calcium hydroxide
How does calcium carbonate react to become calcium oxide?
It needs to be heated strongly. There is a loss of Co2.
How does calcium oxide react to become calcium hydroxide?
Water is added.
How does calcium hydroxide become calcium carbonate?
It gains Co2.
How to react calcium carbonate to make calcium oxide.
- Weigh a limestone chip on a tin lid, record the mass.
- Place a lid on tripod and heat strongly from above.
- Try to make it glow for 10-15 minutes.
- Let the apparatus cool and then weigh and record the new mass.
- Keep your lid + chip for the next stage of experiment.
Calcium carbonate- calcium oxide. What is the change in mass? Why did the mass change?
The mass decreases. This is because carbon dioxide was lost.
What is the word equation for calcium carbonate to calcium oxide?
Calcium carbonate➡Calcium oxide+Carbon Dioxide
What is a thermal decomposition reaction?
A compound that is broken down by heat.
What happens when calcium oxide is reacted with water?
Calcium hydroxide is produced.
LEARN:The following stages are for the reaction between calcium oxide to calcium hydroxide.
- Put the contents of the lid into a dry beaker.
- Put a couple of drops of water onto the solid.
- Write down observations.
What happens during the reaction between calcium oxide and water?
The lump crumbles, a hissing sounds is heard and steam is produced.
What does an exothermic reaction mean?
It means that heat is given out.
What is the word equation for calcium oxide to calcium hydroxide?
Calcium oxide+water➡Calcium Hydroxide.
What happens to calcium hydroxide when universal indicator is added?
It turns blue, so the solution is alkaline.
What happens when you blow into the calcium hydroxide with a straw?
It goes cloudy. The solution becomes limewater or calcium hydroxide solution. The cloudiness is calcium carbonate, so you have gone right back to where you have started.
What chemical is common salt?
Sodium chloride.
What methods can be used to obtain salt?
- Solar evaporation.
- Solution mining.
- Underground mining.
How does solar evaporation work to obtain salt water?
Sea water is run into large salt pans and evaporated by the sun until salt crystallises.
How does solution mining work?
A hole is bored into the underground salt deposit and two pipes are lowered into it. Water is pumped down one pipe and allowed to dissolve the salt. brine ( a solution of salt) is pumped up to the surface through the second pipe.
How does underground mining world?
The salt is physically dug out of the ground in an operation involving drilling, cutting and blasting the rock. After the salt is removed and crushed, a conveyor belt hauls it to the surface. Most salt produced this way is used as rock salt for road ‘gritting’ or ‘salting’ during the winter.
What are the four steps to obtaining rock salt?
- Addition of water- the salt will dissolve in the water but the sand will not.
- Stirring- speeds up dissolving of the salt.
- Filtration- to remove the insoluble sand.
- Evaporation- to remove water from the salt solution. To leave salt crystals.
Define desalination.
The process of making pure water with salt water by removing the salt from the water.
How does Distillation work?
The solution is heated and the solvent evaporates. The vapour then passes into a Liebig condenser, where it condenses (turns back into liquid). The solute does not evaporate, so it remains in the flask.
