Chemistry 3 Flashcards
How were elements in the early periodic table arranged?
By relative atomic mass.
How did the periodic table get its name?
Similar properties appeared periodically.
What are the properties of alkali metals?
Silvery solids.
Stored in oil due to reactivity.
Low density. (First three less dense than water).
What compounds are produced when alkali metals react with non-metals?
White solids that dissolve to form colourless solutions.
How do alkali metals react with water?
Alkali metal + Water (goes to) Metal hydroxide + Hydrogen
What are the properties of halogens?
Have coloured vapours.
What are halogens called when they gain an electron?
Halide ions.
Displacement reactions with halogens.
A more reactive one will displace a less reactive one.
Properties of transition metals.
Good conductors of heat and electricity. Dense. Strong. Shiny. Form colourful compounds. Good catalysts. Can form more than one ion.
How do transition metals compare with alkali metals?
Less reactive. Denser. Stronger. Harder. Higher melting points except Mercury.
How is scum formed?
Calcium and magnesium ions in the water react with the soap to make scum.
What is scale?
It forms on the inside of pipes when temporary hard water is heated.
How do you soften temporary hard water?
1) Hydrocarbonate ions are from dissolved magnesium and calcium Hydrocarbonate.
2) When heated the Hydrocarbonate ions decompose to produce carbonate ions.
3) These combine with magnesium and calcium ions to form insoluble precipitates of magnesium and calcium carbonate.
4) These are the scale which is found in pipes.
5) As there are fewer calcium and magnesium ions in the water, it is now soft.
Why can’t you soften permanent water like temporary hard water?
Contains salts which don’t decompose and form insoluble precipitates once heated.
Softening both types of water- Adding sodium carbonate.
Added ions react with the calcium and magnesium ions to make insoluble precipitate of calcium and magnesium carbonate.
Softening both types of water- Ion exchange resins.
Columns contain many sodium ions inside of them which are trapped on insoluble resins. These ions are exchanged for magnesium or calcium ions.
Na2Resin + Ca2+ (goes to) CaResin + 2Na+
Treatment of drinking water.
1) Water goes through mesh screen to remove big things.
2) Chemicals added to make solids and microbes stick together.
3) Filtered through gravel beds.
4) Chlorine added to sterilise it. This kills microbes.
Filters.
Carbon removes chlorine taste.
Silver kills bacteria.
Advantages of adding fluorine.
Reduces tooth decay.
Advantages of adding chlorine.
Kills microbes and prevents disease.
Disadvantages of fluorine.
High doses can cause cancer.
People cannot chose if they want it.
Some areas may already have high amounts.
Disadvantages of chlorine.
Increase certain cancers.
Can react with natural substances to produce toxin by product which could cause cancer.
Pure water.
Distillation.
Boiling and condensing. Ions don’t evaporate with water so the are removed.
Expensive.
Bond making.
Exothermic.
Bond braking.
Endothermic.
Overall energy change.
Energy of bond braking - Energy of bond making.
Negative overall energy change.
Exothermic.
Positive overall energy change.
Endothermic.
What is the activation energy?
Minimum amount of energy required by reacting particles to brake their bonds.
How does a catalyst work?
Provides another pathway for the reaction which has a lower activation energy.
What is the reaction between hydrogen and oxygen?
Exothermic.
How can you capture the energy released during the reaction between oxygen and hydrogen?
Using a fuel cell or a combustion engine.
Combustion engines.
Only water is formed.
But,
You need to have a specific engine which can be costly. Also, due to hydrogen being explosive and dangerous, it can be difficult to store safely.
Hydrogen fuel cells.
It doesn’t run out or have to be recharged which is why it may be better than a battery.
Fuel cell vehicles don’t produce any pollution, the only by products are water and heat.
But,
Hydrogen takes up a lot of room as it is a gas.
Difficult to store.
Hydrogen fuel can be made from electrolysis or hydrocarbons whine use electricity which would have been generated by the burning of fossil fuels.
What is a titration?
Allows you to identify the amount of volume of a reactant at is needed to react completely with a volume of another reactant.
How do you do a titration?
1) Use pipette and measure volume of alkali.
2) Put it in a flask with indicator.
3) Get acid and put in burette. Run a small amount of acid through the tap.
4) Take a reading of the acid from the bottom of a meniscus.
5) Add acid to alkali a drop at a time towards the end.
6) Indicator change colour when neutralised.
7) Record volume of acid in burette.
8) Calculate the amount of acid needed to neutralise the alkali.
9) Repeat.
10) Calculate an average/ mean.
Give examples of indicators.
Methyl orange- Yellow in alkalis and red in acids.
Phenolphthalein- Pink in alkalis and colourless in acids.
Barium.
Green.
Lithium.
Crimson.
Sodium.
Yellow.
Potassium.
Lilac.
Calcium.
Red.
How do you carry out a flame test?
To get a clean wire loop, dip it in hydrochloric acid and rinse using distiller eater. Get a clean wire loop and place in sample of the compound. Put in blue part of flame.
Precipitation reactions- Calcium.
White.
Precipitation reactions- Copper 2+
Blue.
Precipitation reactions- Iron 2+
Green.
Precipitation reactions- Iron 3+
Brown.
Precipitation reactions- Aluminium
White but redissolves in excess sodium hydroxide to form a colourless solution.
Precipitation reactions- Magnesium.
White.
How do you carry out a precipitation reaction?
Add some sodium hydroxide to the solution.
Testing for negative ions- Carbonate ions.
React a substance with an acid, if a gas is given off which turns limewater cloudy, the gas is carbon dioxide and it must contain carbonate ions.
Testing for negative ions- Halide ions.
Add dilute nitric acid to either chlorine, bromine or iodine. Then add silver nitrate solution.
Halide ions- Chlorine.
White precipitate of silver chloride.
Halide ions- Bromine.
Cream precipitate of silver bromide.
Halide ions- Iodine.
Yellow precipitate of silver iodide.
Testing for negative ions- Sulphate ions.
Add dilute hydrochloric acid and then barium chloride solution. A white precipitate of barium sulphate means the original compound was a sulphate.
What are the industrial conditions for ammonia?
450 degrees
200 atmospheres
Iron catalyst
Properties of alcohols.
Flammable.
React with sodium to give hydrogen and alkoxides.
First three dissolve completely in water.
Properties of carboxylic acids.
Can make strong and weak acids.
Strong is when the acid molecules completely ionise in water and release H+ ions.
Making ethanoic acid.
Ethanol + Oxygen (goes to) Ethanoic acid + Water.
It is made by oxidising ethanol. It can be oxidised using oxidising agents or by microbes which cause ethanol to ferment.
Properties of esters?
Volatile.
Don’t mix well with water.
Uses of esters.
Perfumes.
Flavourings.
Nail varnish remover.
Functional group of esters.
-COO-
Functional group of carboxylic acids.
-COOH
Uses of carboxylic acids.
Soaps.
Ethanoic acid is in vinegar.
Preparation of esters.
Uses of alcohols.
Drinks.
Fuels.
Solvents.
Functional group of alcohols.
OH
What is a homologous series?
Group of chemicals that react in a similar way as they have the same functional group.
