Mass Calculations, Electrolyisis, Metals And Equilibria T5 Flashcards
What happens to atoms during a chemical reaction?
No atoms are created and no atoms are destroyed, this means there are the same number and types of atoms on each side
Why might the mass increase in a reaction?
If the mass increases, it’s probably because at least one of the reactants is a gas that is found in air. Before the reaction, gas is floating in the air and floats into the reaction vessel and
Why might the mass decrease in the reaction?
If the mass decreases, it’s probably because some, or all, of the reactants are solids, liquids or aqueous and at least one of the products is a gas. Before the reaction, any solid, liquid or aqueous reactants are contained in the reaction vessel, if the vessel isn’t sealed, gas can escape when its formed
What is a closed system reaction?
Where nothing can get in or out so the mass doesn’t change
What is the relative formula mass?
The atomic masses of all of the atoms in it’s formula added toegther
What is the empirical formula?
The empirical formula tells you the smallest whole number ratio of atoms in the compound
What is the empirical formula of glucose?(C6H12C6)
CH2O
What is “The mole”?
The mole is simply the name given to a certain number of particles
What is Avogrado’s constant?
6.02 x 10^23
How do you work out the number of moles?
Number of moles = mass in g / total relative mass
How do you work out concentration
Concentration = mass of solute / volume of solution
What are the typical properties of transition metals?
They’re relatively hard and strong,conduct heat and electricity, they have high melting and boiling points and have high densities
What does a catalyst do?
A catalyst up the rate of reaction without being changed. Iron is used as a catalyst for making ammonia.
Why are pure metals malleable?
Because they have a regular arrangement of identical atoms. The layers of ions can slide over each other.
How are alloys made?
Alloys are made by adding an extra element to the metal to make it stronger, this makes the atom less regular and so they don’t easily slide over each other
What happens when metals corrode in the presence of oxygen?
They form metal oxides
Why is the corroding of metals a redox reaction?
Because the metal loses atoms , it’s oxidised while the oxygen gains them
What is rusting?
Rusting is the name for corrosion of iron, rusting only happens when the iron is in contact with both oxygen and water
What is sacrificial protection?
This involves placing a more reactive metal with iron. Water and oxygen react with this ‘sacrificial metal’ rather than the iron
What is galvanising?
Galvanising is an example of sacrificial protection, where a coat of zinc is put over an iron object
What is electroplating?
Electroplating is coating the surface of a material with another metal using electrolysis
How do you electroplate?
The cathode is the object you’re going to electroplate, the anode is the bar of metal you’re using for the plating. Your electrolyte is a solution containing metal ions of the metal you are plating. The anode’s ions move over and deposit themselves onto the cathode
What does oxidation mean?
The reaction with, or the addition of oxygen
What is reduction?
The removal of oxygen
What type of reaction is combustion?
Exothermic
What is a reactivity series?
A reactivity series is a table that lists metals in order of their reactivity
Why is carbon often included in a reactivity series?
A metal’s position in the reactivity series compared to carbon dictates how it’s extracted from its ore
What metals are placed at the top of a reactivity series?
The most reactive ones, but the least resistant to oxidation
How can you measure how reactive a metal is?
The more easily a metal atom loses its outer electrons and forms a positive ion
What experiment can you do to test the reactivities of metals?
Place little pieces of various metals into dilute hydrochloric acid, put lit splint over it after a certain amount of time, the louder the bang, the more reactive the metal is. This is because metals have a reaction with the hydrochloric acid which produces hydrogen, hydrogen produces a big bang when a lit split comes in contact with it
What is the formula for a reaction with a metal and water?
Metal + water = metal hydroxide + hydrogen
What is the name for when reduction and oxidation happen simultaneously?
Redox reaction
What is a displacement reaction?
A more reactive element reacts to take the place of a less reactive element in a compound. During a displacement reaction, the more reactive metal is oxidised and the less reactive metal is reduced
What is a metal ore?
A metal ore is a rock which contains enough metal to make it economically worth while to extract the metal from it
What metals need to be extracted using electrolysis?
Metals which are higher than carbon in the reactivity sereis
What metals can be extracted using reduction with carbon?
Metals below carbon in the reactivity series
Why is electrolysis more expensive than reduction with carbon
In order to electrolysis, you need large amounts of electricity, electricity is expensive
How does bioleaching work?
This uses bacteria to separate metals from their ores. The bacteria get energy from the bonds between the atoms in the ore, separating out metal from the ore in the process
How does phytoextraction work?
This involves growing plants in soil that contain metal compounds. The plants can’t use or get rid of the metals so they gradually build up in the leaves. The plant then can be harvested, dried and burned in a furnace. The ash contains metal compounds
What is the life cycle assessment?
The LCA looks at each stage of the life of a product
Choice of material, manufacture, product use and disposal
What are reversible reactions?
Reactions which go forwards and backwards
What is equilibrium?
When the forward reaction happens at the same rate as the backwards reaction, this is equilibrium
What is the Haber process?
During the Haber process, nitrogen and hydrogen form to create ammonia
What is a closed system?
A closed system just means that none of the reactants or product can escape
What 3 things change the position if equilibrium?
Temperature, pressure and concentration
What is le chatelier’s principle?
The principle states that if there’s a change in concentration, pressure or temperature in a reversible reaction, the equilibrium position will move to help counteract the change
