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12 Cards in this Set
- Front
- Back
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Test for aldehydes and ketones |
- Acidified Potassium dichromate orange to green |
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Test for C=C bonds |
- Bromine water, colour change from orange to colourless |
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Test for phenol |
- Iron (III) chloride, yellow to colourless |
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Describe bond angles and shapes |
- There are 2/3/4/6 regions of electron density around the central atom. - Regions of electron density, repel as far apart as possible to minimize repulsion - giving bond angles 180/120/109/90 - names linear/ bent/triangular planar/ tetrahedral/ octrahedral
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Dot and cross structures cannot account of the bonding in some molecules such as B2H6, why do chemist continue to use dot and cross structures |
- It works well for the majority of molecules |
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Describe properties of ionic substances |
- High melting point - strong electrostatic attraction between ions needs much energy to overcome - Soluble in water - ions can be hydrated/ from strong ion-dipole bonds to water molecules - Conduct when molten - ions free to move in liquid solution |
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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 electrostatic forces between ions - Small amount of energy needed to separate ions |
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Explain why calcium oxide has a high melting point? |
- Has ionic structure - strong electrostatic forces between ions - a lot of energy needed to break the bonds |
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How does adding -SO3H or -SO3-N+ change properties of organic substance? |
- Make more soluble in water - Ionic -SO3- groups are strongly hydrated in water |
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Describe splitting in nmr |
- Doublet ( split into 2) implies 1Hs on adjacent (neighboring) carbon - Triplet (split into 3 ) implies 2Hs on adjacent ( neighboring) carbon - Quartet (split into 4) implies 3Hs on adjacent (neighboring) carbon |
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Compare the structure of carbon dioxide with silicon dioxide |
- CO2 gas at room temperature , SiO2 solid with very high melting point - CO2 , simple molecule, 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 network of covalent bonds - CO2 slightly soluble in water as lone pair on O atoms in CO2 can form (limited) H- Bonds to H on water molecules |
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Why is it good to bury CO2 in deep oceans? |
- CO2 responsible for green house effect - melts polar icecaps or sea level rise, climate change - adding CO2 to sea water reduces water pH technology not yet developed or technology very expensive |
