Science Additional - Chemistry 3

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  • Created by: alliyah14
  • Created on: 06-01-16 22:53
What charge does an atoms nucleus have?
Atoms have a postive nucleus.
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What charge does an atoms electrons have?
Atoms have electrons which are negatively charged
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What is the layers called in which electrons move around the nucleus in?
The layers are know as shells.
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When atoms form bonds what do they make?
Atoms can form to make molecules or compounds.
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What happens to the charge of the electrons if an atom is lossed or gained?
If an atom is lost the charge is postive, whereas if an atom is gained the charge becomes negative.
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What are charged atoms know as?
They are know as ions.
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When do two ions attracted to one another and join together?
This happens when a postive ion meets a negative ion. This is called ionic bond.
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What is a covalent bond?
When non-metal atoms combine together they form colvalent bonds.
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Do colvalent bonds share electrons?
Colvalent bonds have a shared pair of electrons because the bond is a shared air, no atom losses electrons.
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What is a molecular formula?
It shows the number and the type of atoms in the molecule.
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What is a displayed formula?
This is where the atom and the covalent bond in the molecule is in a picture.
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Carbon Dioxide
CO ²
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Hydrogen
H ²
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Water
H ² O
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Hydrochloric
HCl
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Calcium
CaCl ²
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Carbon monoxide
CO
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Magnesium Chloride
MgCl ²
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Calcium Chloride
CaCO ³
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Sulfuric Acid
H ² SO⁴
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Magnesium Sulfate
MgSO⁴
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How are chemical changes shown?
Chemical changes are shown using chemical equatios.
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Whta does chemical reaction do with heat energy?
Chemical reactions can either release heat energy, or take in heat energy.
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What is an Exothermic Reaction?
One which givens out energy to the surroundings, usually in the form of heat, which is shown by a rise in temperature.
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What is an Endothermic Reaction?
One which takes in energy from the surroundings, usually in the form of heat, which is shown by a fall in temperature.
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What happens when enerrgy is supplied and released to bonds?
Energy must always be suplied to break bonds, whereas energy is always released when bonds form.
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What happens to the bonds during a chemical reaction?
Old bonds are broken and new bonds are formed.
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What happens when energy is supplied and released to break / form bonds?
When energy is supplied to break existing bonds its a endothermic process. When energy is released new bonds are formed so this is a exothermic process.
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How does endothermic reactions and exothermic reaction occur?
In an endothermic reaction the energy required to break the bonds is greater than the energy released. In an exothermic reaction the energy released id greater than the energy used to break old bonds.
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What is Calorimetric?
Involves heating water by burning liquid fuel.
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What is the rate of reaction?
This is how fast the reacts are changed into products (the reaction is over when the reactants are used up).
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Give examples of slow reactions
Examples of slow reactions are rusting of iron and chemical weathering - like acid rain damage to limestone buildings.
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Give examples of a moderate speed reaction
An example is a metal (e.g magnesium) reacting with dilute acid to produce a gentle stream of bubbles.
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Give an example of a fast reaction
Burning is a fast reaction but an explosion is a faster reaction that releases a lot of gas.
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What two ways can measure the rate of reaction?
You can measure how quickly the gas is produced by measuring the change in mass or measure the volume of gas given out.
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Explain the process of measuring the change in mass
If you were to carry out the experiment on a balance, the mass will fall as the gas is released.
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Explain the process of mesuring the volume of gas given off
You would use a gas syrine to measure the volume of gas given off after regular time intervals.
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What does the rate of reaction depend on?
The collision frequency (how often they collide, the more they collide the faster the reaction). Also energy transferred during a collision. Particles have to collide with enough energy to be successful.
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If you have more reactant what does it lead to?
More reactant used means more product formed.
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What is yield?
The amount of product you get from a reaction.
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What is directly proportional to the amount of product?
The amount of product is directly proportional to the amount of limiting reactant ( the reactant that is totally used up). Once all of the limiting reactant is used the reaction is finished.
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What four things does the rate of reaction depend on?
Temperature, concentration (pressure), catalyst and the size of the particles.
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Collision theory - Temperature
Increasing the temperature all the particles move faster leading to more collisions as they are going faster ang have more energy.
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Collision theory - Concentration (pressure)
Increasing the concentration means the particles are more crowded together leading to more collisions.
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Collision theory - Catalyst
By having a catalyst it will increase the number of successful collisions as the catalyst speeds up the reaction, meaning the partcles will collide more.
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Collision theory - Size of the particles
Having a larger surface area means other partciles can get toit more easily.
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What does the slope represent on a rate of reaction graph?
The slope of a graph the reactions speed. The steeper the graph, the faster the reaction.
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How do you calculate the rate of reaction using the slope?
To find the average rate on a slop at a specific point you draw a line until you reach the line.
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What is Relative Atomic Mass?
In the periodic table, the elements all have two numbers. The bigger one is the relative atomic mass.
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What is Relative Formula Mass?
If you have a compound like MgCl then it has relative formula mass, which is all the relative atomic masses added together.
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What happens to atoms during a chemical reaction?
During a chemical reaction no atoms are destroyed and n atoms are created. This means there are the same number and types of atoms on each side of a reaction equation.
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What does conserved mean during a reaaction?
Because no mass during a chemical reaction is lossed nor gained its called a conserved reaction.
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What are the three important steps of calculating masses in reactions?
Firstly write out the balanced equation then work out Mr. After that apply the rule of divide to get one, theen multiply to get all.
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What is Atom Economy?
Its the percentage of reactants changed to useful products.
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What does 100% atom economy mean?
This means that all the atoms in the reactants have been turned into useful (desired) products. The higher the atom economy the 'greener' the process.
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Why is high atom economy better for profits?
Raw materials are expensive to bu, and waste products can be expensive to remove and dispose of responsibility.
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Why is high atom economy better for the environment?
If the atom economy is low there is a lot of waste which means its not green.
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What is the formula for Atom Economy?
Total Mr of desired product / Total Mr of all products x100
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What is percentage yield?
It tells you about the overall success of an experiment. It compares predicted yield with the actual yield.
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What is the formula for Percentage Yield?
Actual yield (grams) / Predicted yield (grams) x100
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What is the outcome the yield is 100% and 0%?
If there is 100% you got all the products you desired. However if the yield is 0% means there was no reactants converted into products.
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Why do industrial processes want high percentage of yield?
Because they want to reduce waste and reduce cost.
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What are four reason that could lead to the percentage yield not being 100%?
Evaporation, Not all Reactants react to make a product, Fillration & Transferring liquids.
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What is the Batch Production?
This is the most cost effective way of maufacturing drugs but is very labour intensive. This process only operates at certain times.
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What is the Continuous Production?
Its a large scale industrial manufacture of popular chemicals that never stops and it runs automatically. However even though its very consistent its very expensive .
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Why does Pharmaceutical drugs often cost a lot?
It costs a lot as in order to produce the drug they need to do research and development, then trailling and after that manufacturingwhich is labour intensive as its not automatic.
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How much and how long doees it usually take to bring a new drug into the market?
It takes about 12 years and £900 million to develop a ne drug and get it onto the market.
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How do you extract a subtance from a plant?
To extrat a subtance from a plant, it has to be crushed then boiled and dissolved in a suitable solvent. Then, you can extract the subtance you want by chromatography.
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Will pure subtances be seperated during a purity test?
Pure subtances won't be seperated by chromatography - it'll move as one blob.
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How can you identify is a subtance is impure?
If a subtance is impure the melting point will be too low and the boiling point will be too high.
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What are Allotropes?
Allotropes are just different structural forms of the same element in the same physical state. Carbon has quiet a few allotropes.
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What are diamonds used for?
Diamond is used in jewellery and cutting tools.
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What makes Diamonds strong and hard?
Each carbon atom forms four colvalent bonds in a very rigid giant colvalent structure, which makes diamond hards. This makes them ideal for cutting tools.
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Why do Diamonds have high melting points?
All those strong covalent bonds take a lot of energy to break and give diamonds a very high melting points.
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Why can't Diamonds conduct electricity?
Diamonds don't conduct electricity because it has no free electrons.
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What is Graphite used for?
Graphite makes the lead of your pencil.
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Why does Graphite have carbon atoms free to slide over each other?
Each carbon atom ony forms three covalent bonds , creating sheets of carbon atoms which are free to slide over each other.
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Why can Graphite conduct electricity?
As Graphite only has three covalent bonds theres lots of delcalsed (spare) electronsthat can move.
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Why can carbon covalent bonds form Giant Molecular Structures?
Because carbon can form lots of covalent bonds with itself, it can form giant molecular structures like diamond and graphite sheets.
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Do Giant Molecular Structures conduct electricity?
No, they don't have any free electrons or ions.
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What are Fullerenes and what are they used for?
Fullerens are molecules of carbon and can be used to cage other molecules (trap inside their holllow ball shaped structure).
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How are Fullerenes helpful?
As they trap molecules inside their structure it could be used to deliever drugs as slow release inside the body.
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What are Nanoparticles?
The joining together of fullerenes.
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What are Nanotubes useful for?
Nanotubes have huge surface area so it would be good for industrial process as a catalyst to speed up reactions (the bigger the surfaace area the better).
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What charge does an atoms electrons have?

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Atoms have electrons which are negatively charged

Card 3

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What is the layers called in which electrons move around the nucleus in?

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Card 4

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When atoms form bonds what do they make?

Back

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Card 5

Front

What happens to the charge of the electrons if an atom is lossed or gained?

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