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60 Cards in this Set
- Front
- Back
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Why does H2O have a higher boiling temperature than HF? |
Water forms two hydrogen bonds per molecule but HF can only form one |
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How can you stop the end point of a limewater cloudiness test being subjective? |
Standardise technique by using disappearance of a cross as end point |
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What is the trend in thermal stability of metal carbonates? |
Increases down the group |
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Explain why the thermal stability of metal carbonates increases down the group |
Down the group, the size of the metal cation increases Lower charge density Less distortion of the large carbonate ion Less distortion= more stable |
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What is the colour of a sodium thiosulphate titration just before adding starch? |
Pale yellow |
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What are the reagents required for the reaction from C4H9OH to C4H9Br? |
NaBr and H2SO4 |
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What are the reagents and conditions required to convert a halogenoalkane to an alkylamine? |
Alcoholic ammonia, heat and a sealed container |
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What are the reagents and conditions required for a reaction from a halogenoalkane to an alkene? |
Alcoholic potassium hydroxide, reflux and heat |
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What are the reagents and conditions required for a reaction from a Halogenoalkane to an alcohol? |
Aqueous potassium hydroxide, reflux and heat |
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What kind of reaction is the reaction converting a halogenoalkane to an alkene? |
Elimination |
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What kind of reaction is the reaction from a halogenoalkane to an alkylamine? |
Nucleophillic substitution |
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Why is the Sn1 mechanism more stable? |
The carbocation is more stable- the methyl groups surrounding the carbon stabilise the charge of the carbocation |
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What happens in an Sn2 mechanism? |
The halide group and the hydroxide group are simultaneously leaving and joining, the two are weakly bonded at the same time (represented by very long bonds or dashed lines) |
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How do halogenoalkanes cool by change of state? |
They absorb heat from the surroundings when they evaporate, and they can evaporate very easily |
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What are desirable properties of a refrigerant? |
Changes state from gas to liquid and back at a temp. below the temp. of a refrigerator Not toxic, flammable or corrosive |
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What is the most likely source of hydrocarbons that react with NO to form toxic compounds? |
Petrol/diesel |
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What is the effect of the reaction of hydrocarbons with nitrogen dioxide on the breakdown of ozone? |
NO is removed from the atmosphere, so less ozone is broken down |
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Why is there more nitrogen dioxide at high altitudes? |
More NO2 is broken down into NO and O because the UV radiation is more intense |
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Why is it important to maintain the ozone concentration in the upper atmosphere? |
Ozone protects the earth from UV rays Which would otherwise cause skin cancer or genetic damage |
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How does a catalyst speed up a chemical reaction? |
Reduces activation energy By producing an alternative route/mechanism for the reaction Which has a lower activation energy So higher proportion of molecules are above activation energy |
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Why are jet aircraft considered a greater threat to the ozone layer than cars? |
Jet aircraft release NO and NO2 closer to the ozone layer Less NO is lost through different reactions on its way up |
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Going down group 7 from chlorine to iodine, the reducing power of the halide ion... |
Increases |
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Why might a titre value for a sodium thiosulphate titration be inaccurate (besides accuracy of measuring instruments) |
Judgement of colour change at end point may be inaccurate |
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Why is the C-Br bond stronger than the C-I bond? |
Bromine is more electronegative than iodine |
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What would you see in the reaction of an alcohol with sodium? |
Bubbling and fizzing Sodium dissolves |
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Why are the london forces in methane stronger than those in CO2? |
More electrons in methane Larger instantaneous dipoles and induced dipoles Molecules are more strongly attracted to each other |
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As you go down group 2, the solubility of the sulfates... |
Decreases |
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What are the products in the reaction of conc sulfuric acid and potassium chloride at room temp.? |
KHSO4 + HCL |
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As the temperature of a reaction increases, what happens to the Maxwell-Boltzmann distribution? |
Decreases in height and shifts to the right |
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Why is phosphoric acid used in the preparation of hydrogen iodide gas from potassium iodide rather than sulfuric acid? |
Sulfuric acid would oxidise potassium iodide to iodine- phosphoric acid is a weaker oxidising agent |
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What would you see if a test tube of hydrogen halide gas was inverted in a beaker of water? |
Water would rise in test tube because the gas would dissolve |
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What is the reaction between a hydrogen halide and ammonia? |
NH4(g) + HX(g) ---> NH4X(s) |
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What two chemicals would you use to oxidise an alcohol? |
Potassium dichromate Sulfuric acid |
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What are 2 effects global warming may have on the environment? |
Melting of polar icecaps Changing sea currents |
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How does CO2 in the atmosphere lead to global warming? |
Polarisation in bonds in CO2 means it can trap IR radiation |
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Compare the thermal stability of sodium carbonate and magnesium carbonate |
Magnesium carbonate (group 2 carbonate) will decompose when strongly heated Sodium carbonate (group 1 carbonate) will not decompose under a Bunsen flame |
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As group 2 is descended, what happens to the solubility of the hydroxides? |
Increases |
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As group 2 is descended, what happens to the solubility of the sulfates? |
Decreases |
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An increase in pressure on an equilibrium with 3 moles of gases on the left and 2 moles on the right will have what effect? |
Equilibrium shifts towards the right- shifts towards the side with fewer moles of gas |
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How does doing 4 smaller volumes in a titration instead of one larger titration decrease the accuracy of the experiment? |
Smaller titration volume so the percentage error will increase |
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What is the advantage of using ozone instead of chlorine for disinfecting water? |
Ozone doesn't have an unpleasant odour- chlorine does |
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What is a nitrite ion? |
NO2- |
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What two things would you see when calcium nitrate is heated? |
Brown fumes of NO2 White solid melts then solidifies |
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Why is there a difference between the thermal stabilities of group 1 and 2 nitrates/carbonates? |
Group 2 ions have a greater positive charge so the nitrate/carbonate ion is more distorted Results in less (thermal) stability |
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What is the colour change of phenolphthalein when an alkali is added to an acid? |
Colourless to pink |
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What is the colour change of phenolphthalein when an acid is added to an alkali? |
Pink to colourless |
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What are the products of the reaction between butan-1-ol and phosphorus (V) chloride? |
HCl POCl3 C4H9Cl - 1-chlorobutane |
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Why might the temperature of a reaction be kept high, despite the reaction being exothermic? |
Faster rate of reaction To reach the activation energy |
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Why might a reaction with ethanol use a water bath to heat the reaction mixture rather than a bunsen burner? |
Ethanol is flammable- reduce risk |
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What might ethanol be used for in a reaction |
As a solvent |
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What is the role of the chlorine free radical in the breakdown of ozone? |
Catalyst |
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Why are C-F bonds not broken in the atmosphere, while C-Cl bonds are? |
C-F are very strong and therefore harder to break |
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Why do some bonds absorb infrared radiation? |
Polarity in the bond causes resonance |
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What can be said about the oxides of group 2 elements? |
They are basic |
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What are the thiosulphate ions oxidised to in a iodine-sodium thiosulpate titration? |
S4O6 2- |
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What is essential for a species to act as a nucleophile? |
Lone pair of electrons |
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What causes the steamy fumes when HCl is produced? |
HCl reacts with water in the air to form steamy fumes |
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What would you add to butan-2-ol in a lab to make 2-chlorobutane? |
Phosphorus (V) chloride or conc HCl |
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What does the reaction between ethanol and sodium produce? |
Sodium ethoxide and hydrogen CH3CH2O-Na+ (alc) (alc) means dissolved in alcohol |
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What solvent can you add to a solution to identify halide ions? |
Hydrocarbon solvent |
