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AQA A Level Chemistry – Equilibria Questions and Answers What are the two characteristics of a system is in dynamic equilibrium? 1. both forward and backward reactions proceed at equal rate 2. the concentrations of the reactants and products remain constant What is Le Chatlier's principle used for? It is a tool to help predict the effects of temp, pressure and concentration on the position of equilibrium What happens to the position of equilibrium if temperature is increas...

Topic 1. Edexcel Chemistry A level Questions and Answers What is atomic number? -The number of protons in the nucleus of an atom of an element. -All atoms of the same element have the same number of protons. What is the mass number? The total number of protons and neutrons in the nucleus of an atom of an element. What is an isotope? - Atoms of an element with the same number of protons but a different number of neutrons. - Same proton number but different mass number. ...

A-Level Chemistry Bond Angles and Shape Questions and Answers 2 electron pairs around the central atom Shape: Linear Bond Angle: 180 Example: Carbon Dioxide (CO2) 3 electron pairs around the central atom Shape: Trigonal planar Bond Angle: 120 Example: Boron Trifluoride (BF3) 4 electron pairs around the central atom Shape: Tetrahedral Bond Angle: 109.5 Example: Methane (CH4) 5 electron pairs around the central atom Shape: Trigonal bipyramid Bond Angle: 120 and 90 ...

Edexcel A-Level Chemistry Transition Metal Colours Questions and Answers What colours are MnO4- [+7] , MnO42- [+6], and Mn2+ [+2], in an aqueous complex? Purple, Green and Pale Pink respectively What colours are Ti3+ , Ti2+ in an aqueous complex Purple and Violet respectively What colours are VO2+ , VO2+ , V3+ and V2+ in an aqueous complex Yellow, Blue, Green, and Violet respectively What colours are CrO72- and Cr3+ in an aqueous complex Orange and green respectively ...

Common Questions A level chemistry unit 1 Questions and Answer Define the term relative atomic mass of an element. (2) mean mass of an atom of an element divided by one twelfth the mass of a carbon-12 atom State how the molecular mass of a covalent compound is obtained from its mass spectrum (1) the highest m/z value Explain why isotopes have identical chemical properties (1) they have the same electron configuration State what is meant by the term isotopes (1) atoms of...

A Level Chemistry Periodicity Questions and Answers Define group A vertical column. Elements in a group have similar chemical properties as they have the same number of outer shell electrons Define periodicity A repeating pattern of properties shown across different periods What is the s-block? Groups 1 and 2 What is the p-block? Groups 3-8 What is the d-block? Transition elements What is the f block? Lanthanides and actinides Define first ionisat...

AQA A-LEVEL CHEMISTRY Periodicity Questions and Answers BLOCKS What is the s, p, d and f block on the periodic table? S - 1,2 P - 3,4,5,6,7,8 D - Transition Metals F - Bottom. According to whatever the highest energy level is. ATOMIC RADIUS Why does the atomic radius decrease across the period? The increased number of protons pulls the electrons closer to it with minimal change in shielding to prevent that from ocurring. FIRST IONISATION ENERGY What is the genera...

Edexcel A level chemistry practicals Questions and Answers 8)b. measure enthalpy change of decomposition of KHCO3- key points and errors This practical combines two neutralisation reactions: 1. K2CO3 + 2HCL --> 2KCL + H2O +CO2 2. 2KHCO3 + 2HCL --> 2KCL +2H20 +2CO2 The desired reaction is: 2KHCO3 --> 2K2CO3 +CO2+ H2O use Q=mcΔT and ΔH=-Q/n Errors- assume specific heat capacity is the same as water. Heat lost to surroundings. Polystyrene is more insulating than glass so ...

A Level Chemistry - Structure and bonding Questions and Answers ionic bonding the strong electrostatic attraction between oppositely charged ions which two factors affect the strength of an ionic bond? ionic charge ionic radius (greater distance between ions = weaker bond) describe the trend in ionic radius down a group radius increases as atomic radius increases describe the trend in ionic radius for isoelectronic ions ionic radius decreases as atomic number increas...

AQA A-Level Chemistry - Aromatic Chemistry Questions and Answers Benzene An unsaturated carbon ring, with delocalised electrons in the centre, which cannot undergo addition reactions 152 Benzene is more stable than cyclohexene by a certain enthalpy change Electrophilic Substitution The mechanism to add a different R group to a benzene ring. This is the main type of reaction that occurs as the benzene ring is an area of high electron density so requires like charge displacement....

AQA A level Chemistry - test tube reactions Questions and Answers Bromide Ions and Chlorine Yellow/Orange solution Cl2 + 2Br- = Br2 + 2Cl Iodide ions and chlorine Yellow/brown solution Cl2 + 2I- = I2 + 2Cl- Chloride Ions and Bromine Yellow/orange solution No reaction Chloride Ions and Iodine Yellow/Brown solution No reaction Bromide Ions and Iodine Yellow/Brown solution No reaction Iodide ions and Bromine yellow/brown solution Br2 + 2I- = I2 +Cl- ...

Unit 1 - Higher Chemistry, Oxidizing and Reducing Agents Questions and Answers oxidation loss of electrons reduction gain of electrons Good reducing agents are? metals elements are good reducing agents as they have a low electronegativity which means they will lose their outer electrons easily Good oxidising agents are? non-metal elements are good oxidising agents as they have a high electronegativity which means they will gain electrons more easily What is a r...

AQA A Level Chemistry- Organic Chemistry Questions and Answers General formula The simplest algebraic formula that can describe any member of a homologous series Molecular formula The actual number of atoms of each element in a molecule Structural formula Uses letter symbols and bonds to show the arrangement of atoms in a compound Displayed formula A formula showing the relative positioning of all the atoms in a molecule and the bonds between them Skeletal formul...

CC7 Questions and Answers Do simple molecular substances conduct electricity? no, there's no charged particles Why do giant covalent bonds have such high melting point? strong covalent bonds that contain a lot of energy to break How do metals conduct electricity and heat? the positive ions are fixed in a sea on delocalised electrons, which are free to move and carry charge. are metals are insoluble in water yes two giant covalent bonds formed from carbon gr...

aqa a-level chemistry amines Questions and Answers What are the four structures of amines? 1. Primary (1°): RNH2 2. Secondary (2°): R2NH 3. Tertiary (3°): R3N 4. Quaternary (4°): R4N+X-. Why is ETHANOL's (alcohol) boiling point higher than ETHYLAMINE's (amide) despite the similar size and Mr? Both have hydrogen bonding BUT the H bonding in ethanol is STRONGER than in ethylamine as the O-H bond is more POLAR than the N-H bond and has potential for more extensive H bonding. ...

AQA A-LEVEL CHEMISTRY Group 2 Questions and Answers GROUP 2 What are the group 2 elements? Magnesium Calcium Strontium Barium Radium [[NOT BERYLLIUM]]. PROPERTIES What is the general trend about electrons? There are two electrons in the outer s-orbital which goes further. PROPERTIES What are the size of the atoms in group 2? The atoms get bigger down the group. Each element has an extra filled main level of electrons compared with the one above it. ...

As-Level Chemistry Paper 1 Questions and answers First Ionisation Energy down Group 2 Alkali Metals First ionisation energy down Group 2 Alkali Metals goes as follows: 1) The ionisation energy decreases as you go down the group 2) This is due to their being extra shielding for the outermost electrons the further down the group you go as well as the further distance between the outer electrons 3) These two occurrences out weigh the power of the increasing positively charged nucleus as you go...

Chemistry A-Level OxfordAQA Definitions Questions and Answers First ionisation energy The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions Relative atomic/molecular mass The mean mass of an atom/compound of an element, divided by 1/12th of the mass of an atom of carbon-12 Empirical formula The simplest whole number ratio of atoms of each element in a compound Molecular formula The actual number of ato...

OCR A level Chemistry Questions and Answers Electronegativity The tendancy of an atom to attract the bonding pair of electrons in a covalent bond Radical A molecule, atom or ion with an unpaired electron Acid (bronsted lowry theory) A molecule or atom that can donate a proton Base A molecule or atom which can act as a proton acceptor Alkali A water soluble base Standard Conditions 298 K, 100 kPa, 1 moldm^-3 Standard enthalpy change of a reaction (...

AQA A LEVEL CHEM PRACTICALS - PAPER 3 Questions and Answers measuring e.m.f. of electrochemical cells The standard cell potential is the e.m.f. between two half cells making up the cell, measured under standard conditions. clean piece of each metal, e.g. copper and zinc. degrease using propanone, place copper in a beaker with around 50cm₃ 1moldm⁻³ copper sulfate solution, place zinc in a seperate beaker of same concentration and volume zinc sulfate solution join the two beakers with fi...