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15 Cards in this Set
- Front
- Back
Write an equation that shows HCL is a strong acid |
HCL (aq) ---> H+ (aq) + Cl-(aq) |
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Suggest why a solution of pH8 is not suitable for use in eye drops |
Alkali/OH- ions damage/harmful to/irritate the eye |
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Describe the colour changes of potassium diicrhomate if oxidises alcohols or aldehyde |
- Potassium dichromate (if oxidises alcohol or aldehyde) Orange to green |
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Describe the colour change in bromine water when testing for c=c bonds in alkene |
Bromine water - yellow/orange/brown to colourless |
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Describe the colour change in iron(III) chloride in the presence of phenol group |
Iron(III) chloride in presence of phenol group ) yellow brown to purple |
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Dot and cross structure cannot account for the bonding in some molecules such as B2H6 so why chemists continue to use dot and cross structures? |
- it works effectively/ well for the majority of molecules /substances |
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Describe the properties ionic structures |
Ionic structures - properties High melting point - strong electrostatic attractions between ions need much energy to overcome - Soluble in water - ions can be hydrated/from strong ion-dipole bonds to water molecules - conduct when molten ( or aqueous solution if soluble)- ions free to move in liquid/solution and carry charge and create a current |
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Explain why salts containing large cations and large anions are likely to have low melting points |
- Weak ionic bonds or weak electrostatics forces between ions - Small amount of energy needed to separate the ions |
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Explain why calcium oxide has a high melting point |
Calcium oxide has a high melting point - reference to ions or ionic structure - strong electrostatic forces or strong attraction between forces between ions or strong ionic bonds or a lot of energy needed to break ionic bonds |
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How does adding -SO3H, or -SO3- Na+ change properties of organic substances |
- Make more soluble in water, -ionic -SO3- groups are strongly hydrated (form strong ion-dipole bonds) in water |
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Carbon dioxide vs. silicon dioxide |
- CO2 gas at room temp, SiO2 = solid with very high melting point - CO2 = simple molecules, only weak instantaneous dipole-induced dipole bonds between CO2 molecules - need little energy to overcome - SiO2 = covalent network, vast amount of energy needed to break network of strong covalent bonds - SiO2 insoluble in water, water can't break down network of covalent bonds - CO2 slightly soluble in water as lone pair onO atoms in CO2 can form (limited ) H- bonds to H on water molecules |
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Why is it goo d to bury CO2 in deep oceans/ why is it not being done? |
- CO2 responsible for greenhouse effect - melts polar icecap or sea level rise, climate change harming agriculture/ecosystems - adding CO2 to sea water reduce water pH/increase acidity - harms marine life, technology not yet developed or technology very expensive. |
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Give 2 ways of removing carbon dioxide from the atmosphere |
- Increasing photosynthesis /planting more trees - capture and storage by pumping to the ocean floor or sea bed/ pump deep under the sea - capture and storage in (former) oil/gas wells/ porous rock |
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Why is the shape of molecule x important in a biological context ? |
- to be effective x must fit the receptor/active site of the bacteria = molecular recognition - enzyme active site( receptor sites) have specific shapes so only molecules that fit this will react ( produce response), - x bonds or forms intermolecular bonds to the active site |
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Write an equation corresponding to the third ionisation enthalpy of zinc |
- Zn2+ (g) ---> Zn3+ (g) + e- |