As-Level Aqa Chemistry Study Guide Rated A+

Are oxidation reactions usually exothermic or endothermic? {Ans: They are usually exothermic.}What is a macromolecular structure? {Ans: One in which large numbers of atoms are linked into a regular 3D arrangement by covalent bonds.}What is the reversible reaction of chlorine and water? {Ans: Chlorine gas + water forms hydrogen ions, chloride ions and chlorate ions This is reversible.}Define enthalpy of solution {Ans: The enthalpy change when 1 mole of an ionic solid dissolves in a large enough amount of water to ensure that the dissolved ions are separated and don't interact with each other.}What is the enthalpy change of a reaction? {Ans: The overall effect of the breaking and forming of bonds.}What is the shape of CH4? {Ans: Tetrahedral.}What happens if a molecule contains polar bonds? {Ans: You can end up with an uneven distribution of charge across the whole molecule making it polar.}What is the definition of relative molecular mass (Mr)? {Ans: The relative molecular mass is the average mass of a molecule on a scale where an atom of carbon-12 is 12.}What is the relationship between polarity and electronegativity? {Ans: The greater the difference in electronegativity, the more polar