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42 Cards in this Set
- Front
- Back
Word equation for thermal decomposition? |
metal carbonate--> metal oxide + carbon dioxide |
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git good |
shut up cranky |
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Relative atomic mass is? |
Average mass of an element compared to the mass of one twelfth of an atom of carbon 12. |
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Mole equation? |
mass of chemical / molar mass --> #of moles |
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How do you work out the empirical formula? |
1.Write down mass of each element 2.Get relative mass of each 3.Work out how many mols in each 4.Choose smallest amount 5.Divide mols of all other elements by the amount in the smallest one 6.Cry |
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How do you calculate percentage mass? |
(mass of element in compound / relative formula mass) x 100 |
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How do you calculate empirical formulae from percentage composition by mass? |
1.Mass of each element in 100g of acid 2.Relative atomic mass of each element 3.Convert to mols of each element 4.Choose element least present 5.Divide all by smallest |
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What does mols mean? |
The mass of substance containing the same number of fundamental units as there are atoms in exactly 12.000 g of 12C |
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If you have 1cm3 of a solution, how much water must be added to make it ten times more dilute? |
(10-1=9) 9cm3 |
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How do you convert cm3 to dm3? |
Divide by 1000 |
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What's the concentration equation? |
concentration= amount in moles / volume dm3 |
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What does GDA stand for? |
Guideline Daily Amount |
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How do you calculate the amount of sodium to salt? |
Salt it 2.5 times mass of sodium- so multiply by 2.5 |
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What happens in a titration? |
An acid and an alkali neutralise. |
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What colour will litmus paper go in acid and alkali? |
Acid: red Alkali: blue |
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What colour will phenolpthalein go in acid and alkali? |
acid: colourless alkali: pink |
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What colour will screened methyl orange go in acid and alkali? |
acid: pink alkali: green |
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To show an end point, which indicator should be used and why? |
A single one like phenolthalein or methyl orange or litmus because they give a sharp colour change- not universal indicator which gives a range of colours and thus is hard to measure. |
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How to work out the concentration of a solution in titration? |
1.Work out moles of acid used 2.Work out how many moles of alkali used 3.Link the acid with the alkali (whatever the hell that means miss gibbo) |
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What three ways can you measure the amount of gas produced in a reaction? |
1.Upturned burette or measuring cylinder filled with water 2.Burette which works the same 3.Gas syringe |
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At room temp and pressure, 1 mole of gas takes up ____dm3 |
24 |
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What is the limiting reactant? |
The one that gets used up first |
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What is equilibrium? |
When a balance of amounts of reactants and products is reached |
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Equilibrium only works in a closed system, why? |
The chemicals can't get out. |
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How does equilibrium work? |
Initially the forward reaction is fast but then slows as reactants are used up. At the same time, the backward reaction rate increases as more is available to react. Eventually, both are going as fast as each other. |
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What factors can alter equilibrium position? |
Temperature Pressure Concentration |
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What is the contact process? |
A reaction between sulfur dioxide and oxygen to make sulfur trioxide. It's carried out at a compromise temperature of 450 degrees at atmospheric pressure using vanadium pentoxide as the catalyst. Forward is EXO and back is ENDO. |
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What makes strong acids strong? |
ALL hydrogen atoms ionise, whereas in weak only a few do |
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Complete: strong acid <--> ____ + ______ |
hydrogen ions + other ions |
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How do you define a strong acid? |
Complete ionisation in water (like hydrochloric) with many H+ ions |
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Why do weak acids react slower? |
In reactions, it's the H+ ions that actually react. Weak acids have less of those and thus collisions are less frequent. |
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How are kettles de scaled? |
Using acid to react with the calcium carbonate. Weaker acids are used because stronger acids work so quick that it runs the risk of reacting with the element. |
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Give an example of a weak acid |
Ethanoic |
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What is pH used to show? |
Concentration of H+ ions |
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Complete: CH3COOH <--> ____ + ____ |
H+ CH3COO |
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Strong acids ionise completely in water, complete the equation: HCl --> ___ + ___ |
H+ Cl- |
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Despite the fact weak acids do not conduct as well as strong ones, the same amount of gas will eventually be made if the same amount of reactants are used- why? |
Weak acids will use some H+ ions to react and be used up first so more molecules of acid will ionise producing more H+ ions. Either way, the same amount is produced at the end as if a strong acid was used. |
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What does concentration tell us? |
How many moles of acid there are in 1dm3 of a solution. |
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Word equation for when Barium Chloride is added to sodium sulfate? |
barium chloride + sodium sulfate --> barium sulfate + sodium chloride |
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What are the 4 steps to creating clean, insoluble salt? |
1. Mix barium chloride and sodium sulfate to make barium sulfate and sodium chloride
2. Filter the precipitate (barium sulfate) 3. Wash the precipitate with distilled water to remove traces of sodium chloride 4. Dry by leaving in warm place so water evaporates |
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What are spectator ions? |
Don't directly take part in the reaction. E.g. sodium iodide and lead nitrate react but only lead and iodide ions do anything, so the nitrate and sodium are spectators. |
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Hi chloe |
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