C3 - OCR

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AS - Level Science (C3) Flashcards on C3 - OCR, created by ishpreekc on 03/11/2014.
ishpreekc
Flashcards by ishpreekc, updated more than 1 year ago
ishpreekc
Created by ishpreekc over 9 years ago
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Question Answer
What is the Collision Theory For a chemical reaction to happen, the atoms of the reactants have to collide with enough energy.
What factors speed up or affect a reaction? - Temperature - Concentration - Surface Area - Catalyst
What does Temperature do to a reaction? Higher temperature speeds up a reaction. Particles move faster because there is more kinetic energy. which leads to more frequent collisions and harder ones
What does Concentration do to a reaction? A higher concentration means a faster reaction because more particles are likely to collide.
How does the Surface Area affect a reaction? The larger the surface area the faster the reaction. More surface to collide with.
How does a Catalyst affect a reaction? Doesn't get used up. Speeds up rate of reaction. Catalyst lowers the activation energy.
Why is the start of a reaction always the fastest? Because there are more particles so they will collide often as they get used up they slow down.
What is Activation Energy? The minimum amount of energy needed for the particles to react.
What does the rate of reaction depend on? - Frequency of collisions between particles. - Energy with which particles collide.
What is Gas Pressure? Every time gas particles hit the side of the container or each other.
What is the mass number? The biggest number
What is the atomic/proton number? Smaller number
How do you calculate the percentage by mass? 1) Work out the RMM 2) Work out percentage.
How do you workout percentage yield? Yield (what we made) ----------------------------------- x 100 The amount we should have made
What is atom economy? The percentage of the reactant atoms that are converted into the desired product.
Atom Economy RMM of desired product -------------------------------------- x100 RMM of all products or reactants
What are diamond and graphite both made out of? CARBON
What is an Endothermic process Bond Breaking
What is an exothermic process Bond making
What happens in an Exothermic reaction? They release energy and get hot
What happens in an Endothermic reaction? They absorb energy and get cold
What happens if a reaction is Exothermic? More energy released than needed.
What happens in an Endothermic reaction? More energy is needed than released
What are the advantages of the Batch process? - Cheap - Makes a fixed amount -Can be stored until needed
What are the disadvantages of the Batch Process? - Inefficent - Expensive labour costs.
What are the advantages of continuous processing? - Automated (24hrs) - Computer Controlled - Purer - Less energy needed
What are the disadvantages of the continuous process? - Expensive equipment - Large amounts
Why are medicines so expensive? - takes 10 years to develop and test a drug. - Long-term trials on humans are needed - Raw materials are often rare and costly. - Many raw materials are found in plants and are hard to extract. - Research needs to be independently verified
What is chromatography used for? To test the purity of a compound by comparing the speed of movement against a known pure sample. Pure compounds have definite melting and boiling points.
What are allotropes? An element in the same state but different structures.
Properties of diamond? 1) Rigid 3D structure 2) No delocalised electrons ( does not conduct electricity) 3) high melting/ boiling point because of strong covalent bonds.
Properties of Graphite? 1) 2D layered structure. 2) One delocalised electron (conducts electricity) 3) high melting/boiling points
Why do graphite layers slide over each other, while dimond is hard in every direction? Bonded to 3 atom covalent bonds where as diamond is bonded to 4.
What are nanotubes? Can be used in Catalyst systems. Atoms of the catalyst can be attached to the large surface area on the nanotubes.
How are chemicals extracted from plants? Crushing, Boiling, dissolving and Chromatography.
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