3a Flashcards
In the early 1800’s what did they have to go on in terms of the periodic table?
Atomic mass
What was the main fault of Newlands’ law of octaves?
Didn’t leave gaps for undiscovered elements
What was good about Mendeleev’s periodic table?
He left gaps for where he new other elements would be discovered and placed
What do Alkali Metals form with Non-metals?
Ionic compounds
Describe fluorine
Very reactive, poisonous yellow gas
Describe Chlorine
Fairly reactive, poisonous dense green gas
Describe Bromine
Dense poisonous red-brown volatile liquid
Describe Iodine
Dark green crystalline solid or a purple vapour
What does volatile mean?
It evaporates easily/ at low temperatures
Name some properties of transition metals
Good conductors of heat and electricity, very dense, strong, shiny, less reactive than group 1 metals, higher melting points
What makes a good catalyst (section in the periodic table)?
Transition metals and their compounds all make good catalysts
What is the catalyst used in the Haber process for making ammonia?
Iron
What is the catalyst used in the decomposition of hydrogen peroxide?
Manganese(IV) oxide
What transition metal is useful for turning oils into fats for making margarine?
Nickel
Which lathers better, hard or soft water?
Soft
What does hard water produce?
Scum and scale
Why is scum produced by hard water?
There are dissolved calcium and magnesium ions in the water that react with the soap
When heated what does hard water form?
Scale on the insides of pipes, boilers and kettles
Give three examples of why hard water is more expensive to deal with
Need to use more soap to create a lather, badly scaled-up pipes and boilers reduce in efficiency and therefore might need to be replaced, if scale gets on heating element of kettle will become less efficient (scale is a thermal insulator)
What are two advantages of hard water?
Ca2+ ions are good for healthy teeth and bones, less risk of developing heart disease
What are the two types of hardness?
Temporary and permanent
What is temporary hardness caused by?
Hydrogencarbonate ion
What is permanent hardness caused by?
Dissolved calcium sulfate
How is temporary hardness removed?
By boiling, when heated calcium hydrogencarbonate decomposes to form calcium carbonate which is insoluble. Thus solid is the ‘limescale’ in a kettle
Name one way that can soften both types of hardness (adding…)
Adding washing soda (sodium carbonate). The added carbonate ions react with the ions in the water (cal+mag) to make an insoluble precipitate of cal and mag carbonate. means no cal and mag ions to make the water hard
Name one way that can soften both types of hardness (running water through…)
Running the water through ion exchange columns. The columns have lot of sodium ions & exchange them for cal or mag ions in the water that runs through them
What can you use to compare the hardness of water samples?
Titration
What are the four stages that water from reservoirs go through before going to consumers?
Water passes through mesh screen- remove big bits, twigs. Chemicals added make solids and microbes stick together & fall to bottom. Water is filtered through gravel beds- remove all solids. Water is chlorinated- kill off any harmful chemicals left
What other additional steps do some people take after the treated water comes out of the tap?
Filters containing carbon or silver to remove substances from their tap water. Carbon removes the chlorine taste and silver is supposed to kill bugs.
Why is pure water not tapped?
It would be too expensive to distill it all, energy to boil all of the water we use
Name one advantage and one disadvantage of adding chlorine to water
Prevents disease, increase in certain cancer- can react with natural substances in water to produce toxic-by-products
Name one advantage and one disadvantage of adding fluoride to water
Reduces tooth decay, cause cancer and bone problems
What is a reversible reaction?
One where the products of the reaction can themselves react to produce the original reactants
What is Equilibrium?
The amounts of reactants and products will reach a certain balance and stay there
What does the reversible reaction have to take place in for a state of equilibrium to be reached?
A closed system (none of the reactants or products can escape)
In a reversible reaction, what does the ‘position of the equilibrium’ depend on?
Temperature & pressure surrounding reaction. if alter temperature or pressure can move position of equilibrium to give more product & less reactants
If you raise the temperature of a reversible reaction what will happen?
The endothermic reaction will increase to use up the extra heat
If you reduce the temperature of a reversible reaction what will happen?
The exothermic reaction will increase to give out the extra heat
If you raise the pressure of a reversible reaction what will happen?
It will encourage the reaction which produces less volume
If you lower the pressure of a reversible reaction what will happen?
It will encourage the reaction which produces more volume
Does adding a catalyst change the equilibrium position?
No, it will speed up the reaction but by the same amount on each side
What does the Haber process produce and what is it used to make?
It produces ammonia (NH3) which is used to make fertilisers
Nitrogen + Hydrogen = ?
Ammonia
In the reaction to make ammonia, is it reversible?
Yes
What are the industrial conditions needed for the Haber process?
Pressure: 200 atmospheres
Temperature: 450ºc
Catalyst: Iron
Describe why the industrial conditions of the Haber process are set as they are
Higher pressures favour –> reaction, the pressure is set as high as possible to I’ve the best % yield. –> reaction is exothermic so ++ temperature will move the equilibrium the wrong way so yield of ammonia would be best at lower temperatures BUT the rate of reaction is lower at lower temperatures, 450ºc is a compromise.
What state is ammonia after the Haber process?
Formed as a gas but as it cools in the condenser it liquifies and is removed
How is nothing wasted in the Haber process?
The unused hydrogen and nitrogen are recycled
What does the iron catalyst do in the Haber process?
It speeds up the reaction (gets it to equilibrium more quickly and keeps costs down because it also means that the temperature does not have to be raised as high a quick enough rate of reaction
What is the general formula of an alcohol?
C(n)H(2n+1)OH
All alcohols contain the same what group?
-OH
What three properties do the first three alcohols share?
Alcohol are flammable- they burn in air to produce carbon dioxide and water, All dissolve completely in water to form neutral solutions, React with sodium to give hydrogen and alkoxides
Ethanol is the main alcohol in alcoholic drinks, what does it damage
The liver and the brain
What does the reaction between sodium and an alcohol produce?
Hydrogen and an alkoxide
What would methanol do to you if drunk?
Causes blindness
What three things can alcohols be used as?
Drinks, solvents, fuels
Give two example of substances that alcohols can dissolve that water can’t
Hydrocarbons, oils and fats
Why is ethanol used as the solvent for perfumes?
It can mix with both the oils (smell) and the water (bulk)
What is a methylated spirit and what is it used for?
Ethanol with chemicals added to it, used to clean paint brushes and as a fuel
Name two ways ethanol is used as a fuel
Spirit burners, mixed with petrol as fuel for cars
Why is ethanol a good fuel?
Burns quite cleanly, non-smelly, can be formed from sugar cane and therefore is a renewable resource
What is the functional group of carboxylic acid?
-COOH
What is the basic naming system for alcohols?
replace -e with -ol e.g. methane = methanol
What is the basic naming system for carboxylic acids?
-anoic acid e.g. methanoic acid, ethanoic acid
How do carboxylic acids react?
Just like any other acid to produce carbon dioxide and water
What are the salts formed in Carboxylic reactions called?
an -anoate e.g. methanoic acid will form a methanoate
What happens when carboxylic acids dissolve in water?
Produce acidic solutions, ionise and produce a few H+ ions, don’t ionise completely only form weak acidic solutions, higher pH than aqueous solutions of other strong acids with the same concentration
How can ethanoic acid be made?
Oxidising ethanol
If ethanoic acid is dissolved in water what does it make?
Vinegar
What are carboxylic acids with longer chains of carbon atoms used to make?
Sopas and detergents
What are carboxylic acids used in the preparation of?
Esters
Ethanoic acid is a very good solvent for many organic molecules, so why isn’t it usually chosen?
It makes the solution acidic
What are esters formed from and what is usually used?
An alcohol and a carboxylic acid along side an acid catalyst
Alcohol + carboxylic acid –>
Ester + water
What is the functional group of esters?
-COO-
How do you form the name of an ester?
ETHanol + ETHANoic acid –> ETHyl ETHANoate + water
What do esters smell like?
Nice, sweet and fruity
Why can esters be dangerous?
Highly flammable
Do esters mix well with water?
Nope
What are esters used in?
Ointments, solvents, perfumes, flavourings
What four things do you need to think about when using esters?
Inhaling fumes of some irritates mucus membranes, ester fumes are flammable, some esters are toxic, aren’t as volatile or as toxic as some other organic solvents
What colour is the flame of potassium?
Lilac
What colour is the flame of calcium?
Red
What colour is the flame of sodium?
Yellow/orange
What colour is the flame of lithium?
Crimson
What colour is the flame of barium?
Green
