Karteikarten
C3
Karten in diesem Stapel (77)
- 1C3C3
- 2what is an exothermic reaction?one which gives out energy
- 3what is an endothermic reaction?one which takes in energy
- 4what is an example of an exothermic reaction?burning fuels
- 5what is an example of an endothermic reaction?thermal decomposition
- 6how can you measure the amount of energy released in a chemical reaction?measure the temperature of each of the reactants then mix them in a polystyrene cup and measure the temperature of the solution.
- 7is adding an acid to an alkali endo or exothermic?exothermic
- 8is dissolving ammonium nitrate in water an endo or exothermic reaction?endothermic
- 9what must be supplied to break bonds?energy
- 10what is released when bonds are broken?energy
- 11is breaking bonds endo or exothermic?energy is supplied so it is endothermic
- 12is forming bonds endo or exothermic?energy is released so it is exothermic
- 13what is the SHC of water?4.2 j/g/C
- 14what is the equation for energy transferred?energy transferred (j)= mass of water(g) x SHC of water(4.2j/h/C) x temperature change (C)
- 15what is the equation for energy given out per gram of fuel?energy released (j) /
mass of fuel burned (g) - 16what is an example of a slow reaction?rusting of iron or chemical weathering
(acid rain) - 17what is an example of a moderately paced reaction?a metal (eg magnesium) reacting with a dilute acid to perform a gentle stream of bubbles
- 18what is an example of a fast reaction?burning
- 19what is an example of a really fast reaction?an explosion
- 20what are the two ways to measure how fast a gas is produced in a reaction?measure the change in mass by performing the experiment on scales and recording the drop in gas at regular intervals. You can also use a gas syringe to measure at regular intervals. With both methods you need to plot your results on a graph.
- 21what does the rate of a collision depend on?collision frequency and energy transferred in a collision
- 22what does the amount of product you get from a reaction depend on?how much product you start with
- 23more reactant means more what?particles- these go on to have more reactions so create more products.
- 24what is the amount of product you get directly proportional to?the amount of limiting reactant (the reactant that is completely used up)
- 25what does it mean when we say a reactant is in excess?there is still some left after the limiting reactant has stopped the reaction
- 26what increases the amointt of collisions in a reaction?increasing the temperature- the particles are faster with more energy
increasing the concentration/ pressure- the particles are more crowded
smaller solid particles/ bigger surface area-other particles can get to it more easily - 27what increases the number of successful collisions?a catalyst- it gives the reacting particles a a surface to stick o where they can bump in to each other, and reduces the amount of energy needed by the particles before they react. The overall number of collisions isn't increased but the number of successful ones is.
- 28what is relative atomic mass? (Big A, Little r)bigger of the two numbers for an element on the periodic table
- 29what is relative formula mass? (Big M, Little r)all the relative atomic masses of a compound added together
eg- MgCl2= Mg+(2 x Cl) =24+(2 x 35.5) = 95 - 30compounds with brackets in...Example: find the relative formula mass for calcium hydroxide, Ca(OH)2
Method: the small number after the bracket means you multiply everything in the bracket by 2 - 31what always happens to the mass in a chemical reaction?it is conserved
- 32what does conserved mean?no atoms are destroyed and no atoms are created
- 33what is the result of this?equal numbers and types of atoms on each side of a reaction equation. Because of this, no mass is lost or gained
- 34what are the steps to calculate masses in a reaction?1) write out the balanced equation
2) work out Mr- for the two but you want
3 )apply the rule: divide to get one, then multiply to get all (you need to apply the rule to the substance they give you first, then the other one) - 35what is atom economy?the percentage of reactants turned into useful products
- 36what is the equation for atom economy?total Mr of desired products/ x 100
total Mr of all products - 37What does a 100% atom economy mean?all the atoms in the reactants have been turned into useful/ desired products
- 38what does a higher atom economy show?a greener process
- 39what is high atom economy better for?profits and the environment
- 40what are the problems with low atom economy?use up reactions very quickly and create waste, aren't profitable as raw materials are expensive, and waste can be expensive to remove.
- 41what is the best solution for this problem?find a use for the waste products rather than throwing them away. There's often more than one way to make the reactant you want so choose a reaction with useful 'by-products' rather than useless ones
- 42which reactions have the highest atom economy?ones with only one product- they have an atom economy of 100%
- 43what does percentage yield compare?actual and predicted yield
- 44what is the equation for percentage yield?actual yield (g) / x100
predicted yield (g) - 45what does a 100% yield mean?you got all the product you expected to get
- 46what does a 0% yield mean?no products were made
- 47why do you never get a 100% yield in real life?some product or reactant is always lost along the way, no matter how big the scale of production.
- 48what four things could be a reason for not having 100% yield?Evaporation- liquids may evaporate when heated
Not all reactants react to make product-in reversible reactions, the product can turn back into reactants
Filtration- you always loose a bit of liquid or solid when separating them
Transferring liquids - 49when does batch production operate?only at certain times
- 50when does continuous production operate?all the time
- 51why is batch production often the most cost-effective way to produce small quantities of different drugs to order?its flexible so several different products can be made with the same equipment and start up costs are fairly low as the equipment can be bought off the shelf.
- 52what are the disadvantages of batch production?its labour-intensive as the equipment needs to be set up and manually controlled for each batch and then cleaned out at the end and it can be tricky to keep the same quality from batch to batch
- 53what are the advantages of continuous process?production never stops so you don't waste time emptying the reactor and setting it up again, it runs automatically so you only need to interfere if something goes wrong and the quality of the product is very consistent
- 54what is the disadvantage of continuous process?the start up costs are huge and it isn't cost effective to run at less than full capacity
- 55why do pharmaceutical drugs often cost a lot?research and development- it takes about £900 million to develop a new drug
trialing- animal and human trials
manufacture- batch process is labour intensive and there are other costs such as energy and raw materials. Many products need to be extracted from plants which is very expensive - 56how do you extract a substance from a plant?crush it, boil it, dissolve it in a suitable solvent then separate it by chromotography and extract the chemical you want
- 57how do you test for purity using chromotography?pure substances won't be separated by chromotography, it will all move as one blob and have a specific melting and boiling point. eg. pure ice melts at 0 degrees C and pure water boils at 100 degrees C. If the substance is impure it will have a higher/ lower point.. eg ice that melts at -2 may have salt in it
- 58what are 2 allotropes of carbon?diamond and graphite
- 59what is diamond used in?jewellery and cutting tools
- 60what properties make diamonds good for jewellery?they are lustrous (sparkly) and colourless
- 61what properties makes diamond good for cutting tools?it is hard and has a high melting point
- 62what makes diamond hard?each carbon atom has 4 covalent bonds in a very rigid giant covalent structure.
- 63why does diamond have a high melting point?all the strong covalent bonds require a lot of energy to be broken
- 64why doesnt diamond conduct electricity?it has no free electrons
- 65why is the structure of graphite unique?each carbon atom only creates 3 covalent bonds, creating sheets of carbon atoms which are free to slide over each other.
- 66what makes graphite ideal for use in a pencil?the layers are held together weakly so they are slippery and can be rubbed off on to paper to leave a black mark
- 67why does graphite have a high melting point?the covalent bonds need a lot of energy to break them
- 68why does carbon conduct electricity?because only 3 out of its 4 outer electrons are used in bonds, there are lots of delocalised (spare) electrons that can move
- 69why can you get giant molecular structures of diamond and graphite?carbon can form lots of covalent bonds with itself
- 70what do the many covalent bonds mean for the gian molecule structure?it is strong, has a high melting point and can't dissolve in water.
- 71why don't giant molecular structures of carbon usually conduct electricity?they don't have any free electrons- graphite is the exception
- 72what is a fullerene?molecules of carbon shaped like a hollow ball or closed tube
- 73what is buckminsterfullerene?the smallest fullerene- it has 60 atoms of carbon joined in a ball.
- 74what can fullerenes do to other molecules?cage them- the fullerene structure forms around another atom or molecule, which is then trapped inside.
- 75what do you get when you join fullerenes?nanotubes
- 76what are nanotubes?tiny hollow carbon tubes
- 77what can nanotubes be used for?they have a huge surface area so they could help make great industrial catalysts- individual catalyst molecules could be attached to the nanotubes
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- Beschreibung
- AS - Level Chemistry Karteikarten am C3, erstellt von vittoria howard am 10/01/2015.
- Erstellt von
- vittoria howard
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