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106 Cards in this Set
- Front
- Back
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What are the three parts/particles in a atom? |
Protons, neutrons and electrons |
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What does the mass number tell you? |
The total number of protons and neutrons |
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What does the atomic number tell you? |
The number of protons |
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How do you work out the number of neutrons ? |
Subtract the atomic number from the mass number. |
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How do you know how many electrons there are? |
Its the same as the number of protons |
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What are compounds? |
Chemically bonded elements. Which are difficult to separate the two original elements out again |
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What is the definition of isotopes? |
Different atomic forms of the same element, which have the same number of protons but a different number of neutrons. |
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Why must isotopes have the same atomic number but different mass numbers? |
If they had a different atomic number they would be different elements all together |
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What are two popular isotopes? |
Carbon-12 and carbon-14 |
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what is ionic bonding? |
Ionic bonding is the transferring of electrons from one atom to another so that both atoms have a full outer shell and are stable (Happy) |
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Which columns of elements on the periodic table are the ones keen to loose an electron? |
All the atoms on the left hand side of the periodic table. |
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Which atoms are keen to get that extra electron? |
On the right hand side of the periodic table. |
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What do the atoms become? |
They become ions which stick to the atom they transferred electrons with due to their opposite charge. |
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What structure do ionic compounds have? |
A regular Lattice Structure. |
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What are the bonds of a regular Lattice Structure? |
There is a very strong electrostatic forces of attraction between oppositely charged ions, in all directions. |
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What the the main properties of a ionic compound? |
1) They all have high melting points and high boiling points due to the strong attraction between the ions. 2) When ionic compounds melt, the the ions are free to move and they'll carry electric current. 3) They do dissolve in water easily, the ions separate and are free to move in the solution, so they'll carry the electric current. |
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Which groups are most likely to form ions? |
Groups 1&2 , and 6&7 |
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what do ions have the same structure as? |
They have the same electronic structure of a noble gas. |
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How does loosing an electron affect the charge? |
It makes the charge positive. |
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How does gaining an electron affect the charge?
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It makes the charge negative. |
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Which two elements can form ionic compounds? |
Elements from opposite sides of the periodic table. |
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What must the overall charge of any compound be? |
zero |
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In a formula of an ionic compound the negative charges must... |
balance the positive charges. |
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What is the ionic compound sodium chloride made out of? |
Na+ and Cl- |
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What is the ionic compound Magnesium oxide made out of ?
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Mg2+ and O2- |
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What is the ionic compound calcium chloride made out of? |
Cl- and Ca2+ and cl- |
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What is covalent bonding? |
The sharing of electrons between atoms. |
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What are the two types of Covalent substances? |
Simple molecules and giant structures. |
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What are the forces of attraction for a simple molecular substances? |
The forces are very weak. |
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what are the different types of forms that simple molecular substances could be? |
Usually gasses or liquids at room temperature, but they can be solids. |
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What are the main properties of simple molecular substances? |
1) Low melting and boiling points due to the weak intermolecular forces, not the much stronger covalent bonds 2) Don't conduct electricity- no ions so there is no electrical charge. |
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What are Giant covalent structures known as? |
Macromolecules |
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How are ALL the atoms bonded together? |
By strong covalent bonds. |
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What are the main properties of Macromolecules? |
1) High melting and boiling point due to the strong covalent bonds 2) They don't conduct electricity (except for graphite) |
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What are the Three main examples? |
Diamond , Graphite and silicon dioxide(Silica) |
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How is the Diamond structure formed? |
Each carbon atom forms four covalent bonds in a very rigid giant covalent structure. |
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What are the main properties of Diamond? |
1) its the hardest natural substance, so its used for drill tips. 2) it's pretty and sparkly too. |
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How is the graphite structure formed? |
Each carbon atom only forms three covalent bonds. This creates layers which are free to slide over each other. The intermolecular forces between the layers are weak. |
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What are the main properties of graphite? |
1) It is soft and slippery. 2) Graphite is the only non-metal which is a god conductor of heat and electricity. Each carbon atom has one delocalised(Free) electron and it's these free electrons that conduct heat and electricity. |
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How is graphite used in a pencil? |
The layers are held together so loosely by the weak intermolecular forces, that the layers can be rubbed off onto paper. |
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What is silicon dioxide? |
Sometimes called Silica this is what sand is made of. Each grain of sand is one giant structure of silicon and oxygen. |
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What are metal properties due to? |
the sea of free electrons. |
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Where does the delocalised electron come from? |
From the outer shell of every metal atom in the structure. |
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How does this mean it can conduct electricity? |
These electrons are free to move through the whole structure and so metals are good conductors of heat and electricity. |
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What are the electrons also used for in metals ? |
1) To hold the atoms together in a regular structure, these are strong forces or electrostatic attraction between the positive metal ions and the negative electrons. 2) They also allow the layers of atoms to slide over each other, allowing metals to be bent and shaped. |
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What is often used instead of pure metals? |
Alloys, a mix of two or more metals together which creates an alloy with all the properties they want. |
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Why are Alloys harder? |
Because the different elements have different sized atoms. So when another metal is mixed with a pure metal, they new metal atoms will distort the layers of metal atoms making it more difficult for them to slide over each other. |
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What are the two groups of New materials? |
Smart materials and nanoparticles |
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What do smart do smart materials do? |
They behave differently depending on the conditions. |
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What is good example of a smart material? And what can it be used for? |
Nitinol - A shape memory alloy. Its a metal alloy (half nickel, half titanium) when its cool you can bend it and twist it like rubber but when heated above a certain temperature, it goes back to a remembered shape. 1)This can be used for glasses, if accidentally bent you can just pop them into a bowl of hot water and they'll jump back into shape. 2)Also Nitinol is used for dental braces. In the mouth it warms and tries to return to a remembered shape and so it gently pulls the teeth with it. |
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What are nanoparticles? |
Really tiny particles. |
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Nanoparticles include fullerenes which are? |
These are molecules of carbon, shaped like hollow balls or closed tubes. The carbon atoms are arranged in hexagonal rings. Different fullerenes contain different numbers of carbon atoms. |
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Fullerenes can be joined together to form... |
nanotubes- tiny hollow carbon tubes a few nanometres across. All those covalent bonds make carbon nanotubes very strong. They can be used to reinforce graphite in tennis rackets. |
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What are some of the many new uses of nanoparticles being developed? |
1) They have a huge surface to area to volume ratio, so they could help make new industrial catalysts. 2) New cosmetics e.g sun tan cream and deodorant, don't leave white marks on the skin. 3) Nanomedicine - tiny fullerenes are absorbed more easily into the body than most particles. This means they could deliver drugs right into the cells where they are needed. 4) nanotubes- can be used to make lighter, stronger building materials |
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What is it that determines the properties of the plastic? |
The bonds between the different molecule chains. |
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How are weak forces of polymers formed? |
Individual tangled chains of polymers which are held together by weak intermolecular forces. They are free to slide over each other. |
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What are the properties of Thermosoftening polymers? |
1)They don't have cross-linking between chains. 2)The forces between the chains are really easy to overcome meaning its easy to melt. 3)When it cools the polymer hardens into a new shape. 4)You can melt these plastics and remould them as many times as you like. |
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How are strong forces of polymers formed?
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They have stronger intermolecular forces between the polymer chains, called cross-links, that hold the chains together firmly. |
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What are the properties of Thermosetting polymers? |
1)They have crosslinks which hold the chains together in a solid structure 2)The polymer doesn't soften when it's heated. 3)They're strong, hard and rigid. |
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How is Low density polythene made? |
By heating ethene to about 200 degrees, under high pressure |
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What is the main property of Low density polythene and what is it used for? |
Its flexible and is used for bags and bottles. |
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How is High density polythene made? |
It is made at a lower temperature and pressure (with a catalyst) |
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What is the main property of High density polythene and what is it used for?
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Its more rigid and used for water tanks and drainpipes. |
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What do you have to do for a relative formula mass? |
Add up all the relative atomic masses. |
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What is the sign for relative atomic mass? |
Ar |
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What is the sign for relative formula mass? |
Mr |
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formula for number of Moles? |
mass in g (of element or compound) divided by The relative formula mass (of element or compound) |
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What is the formula for percentage mass of an element in a compound? |
Ar x no. of atoms (of that element)
divided by Mr ( of whole compound) All times by 100 |
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What are the 5 steps for finding the empirical formula? |
1) List all the elements in the compound 2) underneath them write their experimental masses or percentages 3)Divide each mass by the Ar for that particular element. 4)Turn the numbers you get into a nice simple ratio, by multiplying and/or dividing them by well chosen numbers 5) Get the ratio in its simplest form |
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What are the three steps to calculate the masses in a reaction? |
1) Write out the balanced equation 2) Work out Mr - just for the two bits you need 3) Apply the rule: Divide to get one, then multiply to get all . |
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What does the percentage yield tell us? |
It tells us about the overall success of an experiment. It compares what you calculate you should get (predicted yield) with what you get in practice ( actual yield) |
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What is the formula for the percentage yield? |
actual yield (grams) ----------------------------------- x 100 Predicted yield ( grams) |
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What is the predicted yield also known as? |
The theoretical yield |
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What would 100% percentage yield mean? |
That you got all the product you expected to get. |
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What would 0% yield mean? |
That no reactants were converted into product, i.e. no product at all was made. |
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Why do you never in real life get 100% percentage yield? |
Some product or reactant always gets lost along way - and that goes for big industrial process as well as school lab experiments. 1) when you filter a liquid to remove solid particles, you nearly always lose a bit of liquid or solid. 2) Sometimes there can be other unexpected reactions happening which use up the reactants. |
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What is a reversible reaction? |
A reversible reaction is one where the products of the reaction can themselves react to produce the original reactants. |
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What is thinking about product yield important for? |
For sustainable development which is about making sure we don't use resources faster than they can be replaced - there needs to be enough for future generations too. |
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what is paper chromatography used for? |
It can be used to separate artificial colours. |
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What are the 4 steps in paper chromatography? |
1) Extract the colour from a food sample by placing it in a small cup with a few drops of solvent(water, ethanol, salt water, ect.) 2) Put spots of the coloured solution on a pencil baseline on filter paper. - don't use pen as it might dissolve in the solvent and confuse everything 3) roll up the sheet and put it in a beaker with some solvent - but keep the baseline above the level of the solvent. 4) The solvent seeps up the paper, taking the dyes with it. Different dyes form spots in different places. |
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How do you interpret the results of paper chromatography? |
A chromatogram with four spots means at least four dyes, there could be 5 dyes with two of them making a spot in the same place. |
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What are the advantages of using machines to analyse unknown substances? |
1) Very sensitive - can detect even the tiniest amounts of substances 2) Very fast and tests can be automated 3) Very accurate |
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What can Gas Chromatography be used for? |
To identify substances. |
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How does Gas chromatography work? |
1) A gas is used to carry substances through a column packed with a solid material. 2) The substances travel through the tube at different speeds, so they're separated. 3) The time they take to reach the detector is called retention time, it can be used to help identify the substances 4) The recorder draws a gas chromatograph. The number of peaks shows the number of different compounds in the sample. |
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The Gas chromatography column can also be linked to a mass spectrometer. Why? |
It can identify the substances leaving the column very accurately. You work out the relative molecular mass of each of the substances from the graph it draws. You just read off from the molecular ion peak. |
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What are the four things that can affect the rate of reaction? |
1) temperature 2) Concentration - or pressure for gasses 3) Catalyst 4) Surface area of solids - or size of solid piece |
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What is the formula for the rate of reaction ? |
Amount of reactant used or amount of product formed --------------------------------------------------------------------------------- Time |
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What are the three different ways that the rate of a reaction can be measured? |
1) Precipitation 2) Change in mass (usually gas given off) 3) The volume of Gas given off |
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What is Precipitation? |
When the product of the reaction is a precipitate which clouds the solution. Observe a mark through the solution and measure how long it takes for it to disappear. The quicker the mark disappears, the quicker the reaction. The result is very subjective - different people might not agree over the exact point when the mark disappears. |
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How is Change in mass used to measure the rate of reaction? |
The quicker the reading on the balance drops, the faster the reaction. This is the most accurate of the three methods. |
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How is the volume of gas given off used to measure the rate of reaction? |
This involves the use of a gas syringe to measure the volume of gas given off. The more gas given off during a given time interval, the faster the reaction. |
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What is the Reaction of Hydrochloric acid and Marble chips used for? |
To demonstrate the effect of breaking the solid up into small bits. |
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How do you record results from the Reaction of Hydrochloric acid and Marble chips. |
1) Measure the volume of gas evolved with a gas syringe and take readings at a regular intervals. 2) Make a table of readings and plot them as a graph. Time goes on the X axis and Volume goes on the Y axis |
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What is the Reaction of Magnesium metal with Dilute HCL used for? |
For measuring the effects of increased concentration This reaction gives off hydrogen gas, which we can measure with a mass balance. |
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What does the Decomposition of Hydrogen Peroxide show? |
Good for showing the effect of different catalysts. |
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Why are collisions needed in reactions? |
More collisions increases the rate of rection |
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What are the three ways of increasing collisions? |
1) Higher temperature - more energy, move quicker 2) Higher Concentration 3) Larger surface area - more area to work on, more frequent collisions. |
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What is a Catalyst? |
A catalyst is a substance is a substance which speeds up a reaction, without being changed or used up in the reaction. |
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How do Catalysts help reduce costs in industrial reactions |
1) Increase the reaction rate, saves allot of money as doesn't need to operate as long 2) Work at lower temp, reduces the energy used up in the reaction which is good for sustainable development 3) They are never used up in reactions, so you can use them again and again. |
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What are disadvantages to using catalysts? |
1) They can be expensive to buy and often need to be removed from the product product and cleaned. 2) Different reactions use different catalysts, so if you make more than one product at your plant, you'll probably need to buy different catalysts for them 3) Catalysts can be poisoned by impurities so the stop working. This means you have to keep your reaction mixture very clean. |
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Definition of Exothermic reaction. |
An exothermic reaction is one which transfers energy to the surroundings, usually in the form of heat and usually shown by a rise in temperature. |
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Definition of Endothermic reaction. |
An Endothermic reaction is one which takes in energy from the surroundings, usually in the form of heat and is usually shown by a fall in temperature. |
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What is the best example of a exothermic reaction? |
Burning fuels - also known as Combustion, that gives out a lot of heat. |
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What is a good example of a Endothermic reaction? |
Thermal decompositions. |
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What is an example of how endothermic reactions also have everyday uses? |
Some sports injury packs use endothermic reactions - they take in heat and the pack becomes very cold. More convenient than carrying around ice. |
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Endothermic and Exothermic can both be... |
Reversible reactions |
