Untitled Flashcard Set

Where is the fingerprint region of an IR spectrum located? From around 1500 -600 cm-1 True or False? All bond types, polar and non-polar, will give rise to a band in an IR spectrum False IR active bonds must be polar rue or False? Weakly polar bonds produce weak bands in an IR spectrum. True True or False? Strongly polar bonds produce weak bands in an IR spectrum False Name the two types of stretching vibration modes in IR spectroscopy symmetric and antisymmetric stretching True or False? Electron density maps can not be created from X-ray diffraction patterns. False Describe three features of the structure of DNA that X-ray crystallography helped Rosalind Franklin identify. Any of: DNA forms a double helix, DNA is double stranded, Twists very 3.4 nm, 10 basepairs/twist. phosphate grps on the outside of double helix True or False? The strength with which proteins bind to the solid support in a cationic exchange column is determined by the relative degree of negative surface charge on each different protein. True True or false? A cationic exchange column has a negatively charged stationary phase (solid support) True True or FALSE? A substance to be separated by TLC that is strongly attracted to the stationary phase will travel more slowely than a substance that is not strongly attracted. True Identify two factors that affect the overall charge on a protein The type of amino acids in the polypeptide chain and the pH of the chemical environment The key information gained from IR spectroscopy is? Functional groups present A hexagon shape present in X-ray crystallography indicates? Benzene Ring What does a peak at 29 m/z in mass spectroscopy indicate? Ethyl fragment CH3CH2+ or aldehyde CHO+ What does a peak at 15m/z in mass spectroscopy indicate? Methyl fragment CH3+ In mass spectroscopy, what does the M+2 peak indicate? The presence of a halogen. In mass spectroscopy, what does the M+1 peak indicate? The presence of carbon 13 isotopes. What is the amino acid charge if the pH>pI molecular mass of the molecular ion What is the amino acid charge if the pH>pI Positive What is the amino acid charge if the pH<pI? Negative define isoelectric point pH at which the amino acid has a net charge of zero (aka as a zwitterion). Gel electrophoresis separates proteins on the basis of what two factors? Size and charge TRUE or FALSE? The longer the protein sample is in the chromotography column the higher the retention time. True In chromatography, what is the mobile phase? A liquid or gas that carries the sample molecules along the column or TLC plate In chromatography, what is the stationary phase? Solid particles to which the sample molecules adsorb Name an enzyme that can be used as a biological catalyst in the production of biodiesel. lipase True or False? Glycerin is a by-product of the production of biodiesel via transesterification of vegetable oil. True What type of fat is vegetable oil? triglyceride Name the two main processes used for synthesising ethanol Fermentation, hydration of ethene Give the names of the three different categories of biofuels First, second and third generation biofuels Name the two methods that can be used to synthesise biodiesel base-catalysed and lipase-catalysed methods What the name for the synthetic process used to synt contact process When designing an optimal synthetic pathway there is a most often a competition between 2 factors. What are they? The yield of product and the rate of formation of product. How many principles of Green Chemistry are there? 12 What is steam reforming? Production of hydrogen from fossil fuels What is the formula to calculate experimental atom economy? Mass of desired product/Mass of all products x 100 What is the formula to calculate theoretical atom economy? (Molar mass of desired product x moles of product/Molar mass of all reactants x moles of reactants) x 100 True or False. Both hydrogen fuel cells in acidic or basic conditions convert H2 & O2 into water. True What do the twelve principles of green chemistry aim to reduce? Waste, energy use, environmental impacts, risks & hazards Calculate the cell volatage produced by the hydrogen fule cell under acidic condition 1.23V Write the equation for the half reaction that occurs at the cathode in a hydrogen fuel cell under alkaline conditions O2 + 2H2O + 4e -> 4OH- Write the equation for the half reaction that occurs at the anode in a hydrogen fuel cell under acidic condictions 2H2 -> 4H+ + 4e- True or false. A fuel cell is type of galvanic cell True When producing Biodiesel from a trigylceride, what are the two products? ester and gylcerol The process of converting one ester to another ester is called _________________ esterfication What is biodiesel made from? Triglycerides (fatty acids) and a short-chained alcohol (eg methanol) Hydration of ethene is produced through the __________ ___________ of products from crude oil catalytic cracking Write the formula for the fermentation of glucose C6H12O6(aq) -> 2C2H5OH(aq) + 2CO2 List the requirements for fermentation Glucose from suitable grain, or fruit. Yeast. Constant temp (37 degrees) absence of air what are biofuels? Fuels produced from plants, algae or animal waste List the 2 ways ethanol can be synthesised Fermentation and hydration of ethene Why is water not added directly to sulphur trioxide in the contact process? This would lead to an uncontrolled reaction. So the sulphur trioxide is added to sulphuric acid first before adding the water. Why is vanadium oxide used as a catalyst in the production of sulphuric acid? Increases the rate of reaction If tempertaure is increased during the Haber process, will the reactant or product be favoured? sulphuric acid If tempertaure is increased during the Haber process, will the reactant or product be favoured? Reactant What is the Haber compromise? Finding a temperature and pressure that produces enough Ammonia in adequate time without excessive costs or risks. 200atm at 450 degrees C In the Haber process, in which direction does the the equilibrium shift if the pressure is increased? right Is the haber process endothermic or exothermic? exothermic What is the formula for the Haber Process? N2(g) + 3H2(g) <-> 2NH3(g) What does the Haber process produce? Ammonia Markovnikov's rule applied to addition reactions with hydrogen halides says that.. the hydrogen atom will be added to the carbon with the greatest number of hydrogen atoms Describe how to test for a primary alcohol. Add an ox agent (EG KMNO4) - it will change temperature Elimination reactions produce _____ compounds Unsaturated Identify two differenet products of condensation reactions Ester + amide The addition of hydrogen to an alkane can also be classified as _____. Reduction True or false - amides are basic? False Describe two different reactions that could be used to produce propan-2-ol Hydration of propene (+ H2O) Substitution of 2-halopropane (+ NaOH) Determine the products of the hydrolysis of ethyl propanoate Ethanol and propanoic acid Identfy two reaction types that produce amines Reduction (of a nitrile) Substitution (of a haloalkane) The condensation of a carboxylic acid and an amine produces which type of compound? amine What two classes of organic compounds react to form an ester? alcohol and carboxylic acid Haloalkanes can undergo elimination or substitution when reacting with NaOH. Which conditions promote elimination? High temp, conc NaOH, ethanol solvent Name the product when 2-chlorobutane reacts with dilute NaOH at room temperature Butan-2-ol Identify the reactant needed to produce hexanenitrile from 1-chloropentane KCN Identify the class of compound produced when a haloalkane undergoes substitution with ammonia (NH3) Amine Determine the reactant needed to produce 2-fluoropentane from pent-2-ene HF Name the product when water reacts with but-1-ene Butan-2-ol Name the product when ethane reacts with chlorine (in UV light) Chloroethane Describe a chemical test to distinguish hexane from hexene Add bromine water, alkene becomes colourless first (without UV light) What colour would you expect to see when potassium manganate (VII) is combined with a) propan-1-ol and b) methylpropan-2-ol a) purple -> colourless / brown PPT b) purple (no change) What colour change is associated with the oxidation of an alcohol with potassium dichromate? Orange to green Can tertiary alcohols be oxidised? No What is produced when a secondary alcohol is oxidised? Ketone Describe the products of the oxidation of a primary alcohol Aldehyde then carboxylic acid Name two common oxidising agents dichromate (VI) / (Cr2O72-) permanganate / manganate (VII) / (MnO4)- Identify the products of complete combustion Water and carbon dioxide Which class undergoes addition? Alkenes What type of reaction do alkanes undergo? substitution What polymer property(s) does degree of crystallinity affect? Hardness & Density Provide an advantage of natural polymers over synthetic polymers Natural polymers are biodegradable due to reversibility of condensation reaction Give an example of a copolymer polyester What is the name given to a polymer formed from two different monomers? copolymer Which polymer is joined by 1-4 and 1-6 glycosidic bonds between alpha glucose molecules? glycogen Name the atom that joins monosaccharides to form a glycosidic bond. oxygen Which structural form/s of polypropene have crystalline regions? isotactic and syntactic What type of intermolecular forces exist between chains of polypropene? dispersion forces What molecule is eliminated in condensation reactions? water The monomer of polylactic acid is? lactic acid Which polymer of polypropylene has the methyl groups alternating along the chain? syntactic polypropylene Which polymer of polypropylene has the methyl groups randomly distributed along the chain? atactic polypropylene Which polymer of polypropylene has the methyl groups on the same side? isotactic polypropylene. The monomer tetrafluoroethene forms which polymer used for coating frypans. Polytetraflurorethene (PTFE) Name the monomer of polyethylene. Ethene What is the significant difference between the induced fit model and the lock and key model of enzyme action? The ability of the enzyme to flex. Two major competing theories exist on the workings of enzymes, Name them Induced fit model, Lock and Key model Interactions between side chains of amino acids in a polypeptide chain can be of four forms. Name three. Ionic bonds, Disulfide bonds, hydrophobic interactions/dispersion forces, hydrophilic interactions/H-bonding These are formed where adjacent polypeptides intereact through H bonding between the peptide B-pleated sheets The coiled spring structure where the side chains extend beyond the helix itself is known as ...? a-helix The _______ structure considers the 3D arrangment of a protein. Quarternary The _______ structure considers the 3D arrangment of a protein. Tertiary The _______ structure of a protein is the local folding of a polypeptide Secondary The _______ structure of a protein is the sequence of amino acids. Primary What is the name given to the form of amino acids where a H+ has been released from the carboxyl group and accepted by the amino group? Zwitterion Name the amino acid without a chiral centre Glycine What is the name for a monomer of protein? Amino acid Hard water contains high levels of "______" Metals ions such as Ca2+, Fe2+, Mg2+ In relation to water solubility, what is the name given to the ionic end of a soap molecule? Hydrophilic In relation to water solubility, what is the name given to the carbon chain of a soap molecule? Hydrophobic What are the products in the reaction between triglycerides and sodium hydroxide? Glycerol and soap molecules Triglycerides consist of how many fatty acids? 3 Through which carbons does amylopectin form a glycosidic linkage? 1 & 4 and 1 & 6. a-glucose polymerises to form which branched glucose polymer? amylopectin a-glucose polymerises to form which unbranched glucose polymer? amylose B-Glucose polymerises to form which unbranched and insoluble polymer? Cellulose Through which carbons do disaccharides form a glycosidic linkage? 1,4 What is the empirical formula of a monosaccharide? CH2O Why are the smaller alcohols e.g. ethanol more soluble in water? Because Polar molecules that H-bond allows increased solubility. Smaller carbon chain does not interfer A substance with a low melting point and high solubility in cyclohexane is most likely to be an _______. Alkane Sequence in order of increasing solubility in water - carboxylic acid, ketone, alcohol Ketone, alcohol, carboxylic acid (dipole only, H-bonding, 2x H-bonding) Which is more volatile - pentane or dimethylpropane? dimethyl propane (branches reduce IMF) Describe the relationship between boiling point and chain length boiling point increases with chain length (increased dispersion forces) What is a homologous series? A group of organic molecules with the same functional group but a different number of carbon atoms in the main chain What is a geometrical isomer? Compounds that have the same atoms but have a different arrangement of atoms around a double bond What type of functional group does a haloalkane contain? Halogens What is the functional group in the nitrile class of organic molecules? A carbon triple bonded to a nitrogen What differs between primary, secondary and tertiary amides? The number of alkyl (R) groups attached to the nitrogen atom Does a 'cis' or a 'trans' geometrical isomer have similar substituents on the opposite side of a double bond? trans What is a structural isomer? Organic molecules that have the same molecular formula but different bonds between the atoms What suffix is used in the naming of the nitrile class of organic molecules? Nitrile What suffix is used to name amides? Amide What functional group do amides have? An amine group attached to a carbon with a carbonyl group attached to it What suffix is used for amines? amine Name the classes of organic compounds that have functional groups that contain nitrogen? Amines, amides and nitriles Name the classes of organic compounds that have functional groups with oxygen in them? Alcohols, aldehydes, ketones, carboxylic acids and esters What functional group do carboxylic acids have? Carboxyl functional group or COOH What molecule are amines and amides derived from? Ammonia (NH3) What is the difference between the positioning of the carbonyl functional group in ketones and aldehydes? Aldehydes have the functional group on an end carbon. Ketones have them on a carbon in the middle of the parent chain What suffix is used in the names of an ester? yl.......oate What does the functional group of an ester look like? They have a carbon that has both a carbonyl group and an oxygen that is linked to another carbon What suffix is used in the names of carboxylic acids? oic acid What is a carboxyl functional group? COOH - a double bonded oxygen and a hydroxyl group attached to the same carbon What is the difference between a primary, secondary and tertiary alcohol? The number of carbon atoms attached to the carbon that the hydroxyl is attached to What class/es of organic compounds contain a carbonyl functional group? Aldehydes and ketones What class of organic compound contains a hydroxyl functional group? alcohols What is a straight chained alkane? A hydrocarbon that contains all single bonds with no branches Where is the hydroxyl functional group located in a primary alcohol? attached to a carbon on the end of a carbon parent chain What suffix is used in the naming of alcohols? 'ol' What is a carbonyl functional group? A double bonded oxygen to a carbon (C=O) What is a hydroxyl functional group? OH What is a functional group? An atom or a group of atoms in an organic compound that determines the reactivity and properties of that compound What is the rule when assigning a number to show the location of a functional group? Always give the carbon that the functional group is attached to the lowest possible number What does the name of a branch end in? -yl What does the suffix "ene" in a name represent? The presence of one or more double bonds What are the prefixes used to represent the number of carbons? List 1-10 Meth, eth, prop, but, pent, hex, hept, oct, non, dec What are the prefixes used to show multiple branches of the same type? Di, tri, tetra and penta What does the suffix "yne" in a name represent? The presence of one or more triple bonds What does the suffix "ane" in a name represent? Single bonds or saturated What is a hydrocarbon? An organic compound that only contains carbon and hydrogen What is the dissociation expression for an acid? Ka = [H+] [A-] / [HA] What is parallax error? The error when the volume of a liquid is read when the eye level is above or below the meniscus. It leads to inaccurate volumes being determined What impact does having water in the flask holding the analyte have in a titration? No impact as the number of moles of the substance remains the same What results in a titration would be deemed concordant? Until you have obtained three titres that differ by less than or equal to 0.1mL What is an aliquot? A fixed volume of liquid measured by a pipette What impact does having water in the burette have in a titration? It will decrease the concentration of the titrant and therefore a greater volume will be needed to neutralise the analyte What does the buffer region look like on a weak acid or base titration curve? It is the (almost) horizontal area that occurs before the equivalence point. What is meant by a standard solution in a titration? A solution whose concentration is accurately known What is the titrant? The solution in a titration whose concentration is known What is the "end point" ? The point in a titration when the indicator changes colour What is a titration? A technique used to determine the unknown concentration of a solution What is the buffer point on a weak acid or weak base titration curve? t is the point where pH = pKa. It is at half the equivalence volume When choosing an indicator for a titration what are you looking for? An indicator whose end point is close to the equivalence point. What is the analyte? The solution in a titration whose concentration is unknown What is the equivalence point? The point in a titration when neutralisation is reached (i.e. when moles H+ = moles OH-) At what point does an indicator change colour? When the pH of the solution changes past the pKa of the indicator How are the acid and its conjugate base different in indicators They are different colours What is an indicator? A chemical substance that changes colour at particular pH values Is an acid strong or weak if it has a low pKa? Strong What is pKa a measure of? strength of an acid What strength is an acid or base that is used as an indicator? weak Is a base strong or weak if its pKb is large? Weak What is pKb a measure of? Strength of base Is Kw temperature dependent? Yes Is the conjugate base of a weak acid, stronger or weaker? Stronger What does Ka represent? The equilibrium constant for the dissociation of an acid in an aqueous solution What is a buffer solution? A solution that resists changes in pH when small quantities of acids or bases are added to it What is the conjugate acid of hydroxide (OH- )? H2O What is a conjugate base? base formed by removing an H+ from an acid What is the Bronsted-Lowy definition of a base? A species that accepts protons What substances make up a buffer? A weak acid and its conjugate base or a weak base and its conjugate acid What is the conjugate base of ammonium (NH4+)? NH3 What is a conjugate acid An acid formed when a base accepts an H+ What type of substance has a pH of 13? Strong base What type of substance has a pH of 7? Neutral substance Which have better electrical conductivity, strong or weak acids (or bases)? Strong acids (or bases) What can be tested experimentally to determine the strength of an acid or base? The electrical conductivity of the acid or base What does it mean if an acid is concentrated? It means it has a large number of moles of the acid in a litre of water If an acid or a base only partially ionises in water what is it called? A weak acid or base What type of substance has a pH of 1? Strong acid Why are acids and bases good electrolytes? Because they can dissociate into positive and negative ions which means they can conduct an electrical charge What does it mean if an acid is dilute The acid has a small number of moles of the acid in a litre of water What is hydronium? H3O+ What is meant by the "strength" of an acid or a base The level of dissociation that occurs in the acid or base. Name an example of a diprotic acid H2SO4 (sulphuric acid) H2CO3 (carbonic acid) Name an example of a monoprotic acid HCl - hydrochloric acid HBr - hydrogen bromide HNO3 - nitric acid CH3COOH - ethanoic acid What is a monoprotic acid? An acid that can donate one proton per molecule Name an example of a triprotic acid H3PO4 (Phosphoric acid) What is a polyprotic acid? An acid that can donate more than one proton per molecule What is a diprotic acid? An acid that can donate two protons per molecule What is the Bronsted-Lowry definition of an acid? A proton donor The strength of an acid is explained by the degree of ... dissociation of the acid at equilibrium in an aqueous solution What is the definition of a strong base in terms of its Kb? High Kb - Strong bases What substance states are included in a dissociation expression? Aqueous What are examples of Weak Bases? Ammonia (NH3), amines What are examples of Weak Acids? Carboxylic acid (R-C(=O)-OH), carbonic acid (H2CO3), aqueous carbon dioxide (CO2 (aq)) Which Acid and Bases (strong or weak) completely ionise in water? strong acids and bases What is the definition of a strong acid in terms of its Ka? Ka > 1 is a strong acid What is the dissociation expression for a base? Kb = [products] / [reactants] What are examples of Strong Bases? All group 1 hydroxides (LiOH, NaOH, KOH, RbOH, CsOH) Barium hydroxide (Ba(OH)2) What are examples of Strong Acids? Hydrochloric Acid (HCl) Nitric Acid (HNO3) Sulfuric Acid (H2SO4) What type of substance does this indicator represent? HIn ⇌ H+(aq) + In-(aq) weak acid How are strong bases defined? defined as having a high Kb How are weak acids defined? defined as having a Ka < 1 How do you calculate Kb? Kb = [BH+ ] x [OH-] / [B] How do you calculate Ka? Ka = [H3O+ ] x [A-] / [HA] How are weak bases defined? Weak bases are defined as having a low Kb How are strong acids defined? Strong acids are defined fully ionising / dissociating (Ka > 1 ) What are acid-base indicators? Weak acids or bases, which dissociate slightly in water and form ions How do we calculate Kw? Kw = Ka x Kb pH + pOH = ? 14 or Kw (at just below 25oC) How is [OH- ] calculated? [OH-] can be obtained using the pH or pOH value: pH + pOH = 14 pOH = 14 - pH pOH= --log10 [OH- ] [OH-] = 10^(-pOH) How is [H+ ] calculated? [H+ ]= 10^(-pH) What is pH? The figure expressing the acidity or alkalinity of a solution on a logarithmic scale What is self-ionisation of water? refers to the reaction in which a water molecule loses a hydrogen ion (leaving OH-) and the hydrogen ion immediately reacts with another water molecule to form a hydronium ion (H3O+ ) Under what circumstances could the numerical value of Kw differ? Different temperatures. Kw is 10-14 at just below 25oC How is pOH calculated? pOH = -log10 [OH-] How is pH calculated? pH = -log10 [H+ ] What is Kw? Kw is the ionic product constant of water. It is the equilibrium constant for the self-ionisation of water. Kw can be used to calculate the concentration of hydrogen ions from the concentration of hydroxide ions in a sol Why is water a weak electrolyte? Because It can self-ionise, but equilibrium lies to the left H2O ⇌ H+(aq) + OH-(aq) What is the conjugate acid of the following base: OH- ? H2O What is the conjugate base of CH3COOH? CH3COO- How does the Brønsted-Lowry model define an acid and a base? Acids as any species that can donate protons (H+). Bases as any species that accept protons (H+) Identify the conjugate base produced in this reaction: NH4+ + OH- ⇌ NH3 + H2O NH3 What is a conjugate base? A base formed by removing a proton (H+) from an acid Identify the conjugate acid produced in this reaction: NH4+ + OH- ⇌ NH3 + H2O H₂O What is a conjugate pair? Two species that differ by a proton (H+) What is an example of a common amphiprotic substance? water, amino acids and hydrogen carbonate ions (HCO3- ) What is an amphiprotic substance? A substance that can act as either an acid or a base What is a conjugate acid? An acid formed when a base accepts a proton (H+) B: + H2O → B:H+ + OH- (B:H+ is the conjugate acid) What is the definition of a weak acid in terms of its Ka ? Ka < 1 Weak acids What is the relationship between the pH range of an acid-base indicator and its pKa value? A higher pKa correlates to a higher end point of the indicator What is the definition of a weak base in terms of its Kb? Low Kb - Weak bases What type of substance does this equation represent? BOH → B+(aq) + OH-(aq) A strong base What happens when the pH of a solution is equal to the pKa of an indicator? indicator will change colour Name the two types of electrochemical cells? Galvanic and electrolytic What does Eθ have to equal to be considered a spontaneous reaction? Positive value What is the standard electrode potential of a half-cell a measure of? This potential is a measure of the energy per unit charge which is available from the oxidation/reduction reactions to drive the reaction What equation calculates the overall cell potential? E°cell = E°cathode - E°anode What are the units for standard electrode potentials? Volts (V) Define the standard electrode potential of a half-cell (Eθ) The standard electrode potential of a half-cell is the voltage of a half-cell compared with a standard hydrogen electrode. Standard electrode potentials are generally written as? Reduction half equation Are the strongest reducing agents positive or negative? Negative What is an electrolyte? A solution that contains positive ions (cations) and negative ions (anions) standard conditions under which standard electrode potentials are measured? 25C, 1 atm and 1M What is an electrode? solid conductor Why does a Galvanic cell need to be separated into two half cells? In order to utilise the current produced and start or stop the spontaenous reaction What is electrolysis? The process by which electrical energy is passed into a cell to cause a non-spontaneous reaction to occur What is the job of the salt bridge in a Galvanic cell? It is a connection between the 2 half cells that allows the movement of charged ions What is an external circuit in a Galvanic cell? Wires that connect the anode to the cathode and allow the movement of electrons to occur What type of a reaction occurs in a Galvanic cell? A spontaneous REDOX reaction What charge does the cathode have in an electrolytic cell? Negative What type of reaction occurs in electrolytic cells? forced non-spontaneous What type of electrode is needed for a molten electrolytic cell? The electrode must be an inert material; have a higher melting point then the molten solution What are electrolytes? An ionic substance which is either molten or an aqueous solution What type of electrochemical cell uses energy from an external source? Electrolytic In an electrolytic cell what charge does the anode have? Positive Eo values are measured under specific conditions. What are they? 1M concentration of electrolyte, 298K and 1 atmosphere What are Eo values? The symbol represents the Cell Potential. It shows the voltage produced in a Galvanic half-cell. What type of electrochemical cell contains a salt bridge? Galvanic What type of chemical reaction occurs in a galvanic cell, Spontaneous, or non-spontaneous? Spontaneous What is a galvanic cell? A cell in which spontaneous oxidation-reduction reactions produce electrical energy What occurs at the cathode? Reduction (gain of electrons) How is the potential cell difference of a galvanic cell calculated? E°cell = E°cathode - E°anode What occurs at the anode? Oxidation (Loss of electrons) What can you do to increase the concentration of gas in a closed system? Decrease the volume, condensing the concentration What does RICE stand for? Ratio, Initial concentration, Change in concentration, Equilibrium concentration True or false? Is the Kc of a reaction temperature dependent? True If Kc is larger than 104 is there significantly more reactant or product? Product True or False? The stronger the electronegativity, the more readily the element will accept electrons. True What energy is required to remove an electron from an element? First What kind of ionisation energy makes elements lose electrons more readily? Low Where can the elements with the lowest ionisation energy be found on the periodic table? Bottom left Can forward and reverse reactions occur at the same time? Yes, within a closed system How can you measure the concentration of an equilibrium using pH? You can measure the change in pH and calculate the H3O+ concentration, then use simple stoichiometry When is a state of dynamic equilibrium reached? When the rate of the forward and reverse reactions are equal What does Kc represent? The equilibrium constant In a reaction where a gas is produced what type of system is required for equilibrium to be reached? Closed system What can you measure using observation in equilibrium reactions? You can observe whether the forward or reverse reaction has occurred if the reactants and products have different colours What is activation energy? The minimum amount of energy required in the collision between reactants for a reaction to occur Why is a substance in a system more likely to react when the temperature is higher? The particles of that substance have more kinetic energy, causing them to collide more often with the other particles in the system, making the reaction occur Are physical changes reversible? Yes, they are reversible as chemical bonds remain unchanged What type of system is it when energy can escape but not matter? Closed system What is a "closed system"? A reaction vessel that does not allow the reactant or product particles to escape Are all reactions reversible? No, for example due to the formation of energetically stable products or loss of products into the environment What is meant by an "open system"? A system that allows matter and energy to be exchanged with the surroundings On an equilibrium graph how do you know the reaction has reached equilibrium? When equilibrium is established the concentration lines are horizontal What happens to the equilibrium position when the reactant concentration is increased? The forward reaction increases and equilibrium moves to the right What does Le Chatelier's principle state? If an equilibrium system is subjected to a change, the system will adjust itself to partially oppose the effect of the change What happens to the equilibrium position when the product concentration is increased? The reverse reaction increases and equilibrium moves to the left What can be changed in a reaction to alter the equilibrium position? Changing the Concentration, temperature, pressure/volume (only applies to gases) When elements lose their valence electrons, do they act as oxidising or reducing agents? The elements are oxidised and act as reducing agents What type of chemical reactions are redox reactions? Single displacement, combustion, electrochemical cells, corrosion What is a corrosion reaction? A reaction where metal reacts with chemicals in the atmosphere. The metal must be more stable as an ion than a solid Can oxidation happen by itself? No, reduction must also occur What does AN OX represent? Oxidation always occurs at the anode What does RED CAT represent? Reduction always occurs at the cathode What is a spectator ion? An ion that exists in the same state on the reactant and product side of a reaction. Its oxidation state does not change. Atoms from what area of the periodic table have multiple oxidation states? Transition metals The sum of the oxidation numbers in a polyatomic ion should equal what? The charge on the ion What does OILRIG stand for? Oxidation is loss of electrons, reduction is gain of electron What is an overall redox equation made up of? The oxidation and reduction half equations and added together What is a half-equation? An equation that represents either oxidation or reduction What should be the sum of the oxidation numbers in a neutral compound equal? zero Will atoms with high electronegativities tend to oxidise or reduce? reduce What is a REDOX reaction? One where both reduction and oxidation occurs simultaneously What occurs to a reducing agent? oxidation What is an oxidising agent? A reactant that causes another reactant to lose electrons and be oxidised and is itself reduced Elements in Group 1 and 2 of the periodic table are more likely to - oxidise or reduce? oxidise What happens to the oxidation states when the atom undergoes oxidation? Oxidation state increases When is Oxygen's oxidation number not equal to -2? In peroxide (H2O2), oxygen has an oxidation number of -1 What is the common oxidation number of Group 2 metals? Group 2 is +2 including - Mg2+, Ca2+ What molecule has oxidation number of 0? Elements including - He, Fe, Li, O2 What happens to the oxidation states when the atom undergoes reduction? oxygen state decreases For monoatomic ions, how is the oxidation number determined? The oxidation number is determined by the charge on the ion Eg, Cu2+ has an oxidation number of +2 When is Hydrogen's oxidation number not equal to +1? In metal hydrides, hydrogen has a oxidation number of -1 Including - LiH What is the common oxidation number of Group 1 metals? Group 1 is + 1 Including - Li+, Na+ What do oxidation numbers represent? They represent the gain or loss of electrons What is oxidation? loss of electrons What is reduction? gain of electrons