WAEP 2016

• materials containing particles in the size range 1-100 nanometres
• such small particle size provides huge surface area to volume ratio -therefore more catalytic sites available for the reactants to come into contact with compared to a sheet/block of metal,, increasing reaction rate

• high surface tension of water
• the strong hydrogen bonding between water molecules ‘pulls’ surface water molecules inwards towards the rest of the water
• this results in the tendency of water to bead instead of spreading out, in order to produce the lowest surface area possible

• the NaCl is dissolving due to the ion-dipole attractions it forms with water
• the solution becomes saturated when maximum amount of solute has dissolved at this particular temperature and then the extra salt added remains visible

<ul> <li>water is highly polar and forms strong hydrogen bonds between its molecules, and will therefore dissolve substances with similar strength IMFs</li> <li>ethanol has the ability to form hydrogen bonds and is therefore soluble in water as its intermolecular forces are strong enough to overcome that of water's</li> <li>ethane has only dispersion forces and is therefore insoluble as its intermolecular forces are not strong enough to overcome the hydrogen bonding of the water</li> </ul> Signup and view all the answers

<ul> <li>atoms will often react to achieve a more stable electron arrangement by gaining or losing electrons, forming charged ions</li> <li>magnesium has 2 valence electrons, which it will lose (since it's easier than gaining 6 electrons) in order to achieve a stable octet, thus forming a cation</li> <li>this results in formation of a 2+ charge because the magnesium now has 2 more protons than electrons</li> <li>chlorine has 7 valence electrons, so it will obtain one more (since its easier than losing 7 valence e-) to achieve a stable octet, forming an anion with an overall charge of 1-</li> </ul> Signup and view all the answers

<ul> <li>addition reactions require the presence of a double bond, which is present in alkenes</li> <li>this double bond is converted (‘broken’) to a single covalent bond and another substance (halogen, hydrogen, hydrogenhalide, water etc) is incorporated, one group adding to the carbon on each side of the double bond</li> <li>alkanes do not have a double bond and can only undergo substitution reactions</li> <li>benzene similarly does not contain double bonds, (the ring structure does but is very stable) and can also only undergo substitution reactions</li> </ul> Signup and view all the answers

<ul> <li>increased number of particles entering the balloon</li> <li>causes an increased number of collisions with the walls of the balloon, therefore increased pressure</li> </ul> Signup and view all the answers

<ul> <li>decreased temperature decreases average kinetic energy of particles</li> <li>this results in slower and less collisions with the walls of the elastic container (balloon), therefore the pressure is lowered and the volume decreases</li> </ul> Signup and view all the answers

<ul> <li>Mg metal has delocalised electrons (mobile charged particles) therefore able to conduct</li> <li>MgCl2 is soluble in water and therefore ions become dissociated (mobile charged particles) allowing electrical conductivity</li> <li>MgCl2 -&gt; Mg2+ + 2Cl-</li> <li>HCl ionises in water to produce ions (mobile charged particles) enabling it to conduct electricity</li> <li>HCl-&gt; H+ + Cl-</li> <li>H2 is composed of discrete diatomic molecules with no mobile charge therefore unable to conduct</li> </ul> Signup and view all the answers

<ul> <li>filtration, to remove solid particles</li> <li>disinfected, kill bacteria and viruses</li> <li>precipitation, remove excess metal ions</li> <li>desalination, remove salt from seawater</li> </ul> Signup and view all the answers

<p>-electrons of an atom are confined to specific energy levels -electrons are able to move between these shells by absorbing (jump to a higher energy level) or emitting (to fall to a lower energy level) particular amounts of energy -the amount of energy absorbed/emitted by these electrons as they move between shells corresponds to particular wavelengths of light which create the CORRESPONDING absorption or emission spectra --these spectra are unique for each element, since the energy levels of the electrons are slightly different for each element -in AAS the known absorption spectrum of a particular element is used and light of a corresponding wavelength is shone through the (atomised) sample being tested -the higher the concentration of the particular element in the sample, the more light it absorbs</p> Signup and view all the answers

<p>-increased pressure = more gaseous particles in smaller volume -results in decreased distance between reactant particles = increased frequency of collisions and hence successful collisions between reactant particles -hence increasing ROR</p> Signup and view all the answers

<p>-increased temperature increaes avg ke of reactant particles -results in GREATER PROPORTION of particles having sufficient energy to overcome the activation energy, -hence increase ROR</p> Signup and view all the answers

<ul> <li>they are produced from renewable sources such as biomass</li> <li>whereas fossil fuels are obtained from non-renewable sources</li> </ul> Signup and view all the answers

<ul> <li>an enzyme is a protein that acts as a biological catalyst -provides an alternative reaction pathway with a lower activation energy, thereby allowing a greater proportion of particles to overcome the activation energy -hence increasing frequency of successful collisions -hence zymase enzyme speeds up the RATE OF FERMENTATION REACTION -1 MARK FOR CONCLUDING SENTENCE</li> </ul> Signup and view all the answers

<p>calculate amount of heat energy that would be released in combustion reaction described (we calculated in part a that there were 513.8057 moles of C2H5OH), so its 513 z 1367 = 702MJ.</p> Signup and view all the answers

<ul> <li>samples can not be in gaseous form</li> <li>samples must be soluble to a degree in the particular solvent being used so that a liquid sample can be prepared</li> </ul> Signup and view all the answers

<p>-use a polar mobile phase with non-polar stationary phase or polar stationary phase with non-polar mobile phase -sample to be analysed is dissolved in the mobile phase and moves through HPLC column -components of the sample will adhere to the stationary phase with different strengths due to the varying polarity of each component (components will also have varying degrees of interaction with the mobile phase) -the components therefore move along the column at differing rates and exit the column at different times, where they can be identified</p> Signup and view all the answers

<p>-same pressure used -same mobile phase -same stationary phase</p> Signup and view all the answers

<ul> <li>pour entire reaction mixture into filter funnel lined with filter paper (weigh dry filter paper, if intending to subtract mass at end)</li> <li>wash reaction vessel several times and add rinsings into filter paper to ensure all solid PPT transferred</li> <li>allow filtrate (NaNO3) to move through filter paper while Ca3(PO4)2 PPT is captured as residue</li> <li>wash residue thoroughly with distilled water and allow to dry completely before weighing (subtract mass of dry filter paper if necessary)</li> </ul> Signup and view all the answers

<p>random error: -accuracy of scales -uneven volume of each of the 10 drops</p> <p>systematic error: -not washing residue thoroughly -not taring scales correctly -some PPT remaining on filter paper when weighing</p> Signup and view all the answers