CHEM 1061 1st EditionExam #2 Study Guide Lectures: 11-20Lecture 11 (February 13)What is Avogadro’s Law? Volume is proportional to amount (In mol). (Pressure and Temperature are constants)What is STP?STP is standard temperature and pressure. When gas is calculated at STP it is calculated at 0 degree Celsius and 1 atm.How can you calculate density using PV=nRT?Using the PV=nRT equation, you can substitute mass/molar mass for n, and rearrange the equation. The rearranged equation would be (molar mass)P/RT=(mass)/V=density.Lecture 12 (February 16)How can you calculate molar mass of a gas using PV=nRT?N is mol, therefore you can rewrite the equation to look like PV=(mass/molar mass)RT and solvefor molar mass while filling in appropriate known values.What is the mole fraction?A mole fraction is the number of moles of a specific gas over the total number of moles.What is an important thing to consider when calculating gases over water?When calculating gases over water you need to take into consideration the vapor pressure of water. You do not need to memorize these values, but they are found on table 5.2 of your textbook.Lecture 13 (February 18)What is the difference between potential and kinetic energy?Potential energy is the energy due to the position of the object. Kinetic energy is the energy dueto the motion of an object. An object must be moving to have kinetic energy.Is E positive or negative when energy is released into its surroundings?When E is released to its surroundings, the reaction is exothermic and has a negative value. As opposed to that when E absorbs energy, it has a positive value and is endothermic.∆E=q + w. What does this mean?This is an equation for change in energy. Q stands for heat and w stands for work. If there is ONLY heat, than work is always 0. If there is ONLY work, than heat is always 0. If both are present you must look at the magnitude of to determine the value of E.Lecture 14 (February 20)What is Enthalpy? What is the variable it is represented by?Enthalpy is the heat absorbed or released at a constant pressure. It is represented by an H.What is an endothermic reaction?An endothermic reaction is one that absorbs or needs energy to complete the reaction and has a positive value of change in enthalpy.How do you calculate Specific Heat Capacity? (c)Specific Heat Capacity is the quantity of heat required to change the temperature of 1 g of an object by 1 Kelvin. To calculate Specific Heat Capacity, use the equation c=q/mass x ∆T. The units for specific heat capacity is J/g x K.Lecture 15 (February 23)What is an important aspect to consider when calculating heat lost to both water and a calorimeter?When heat is lost to both water and a calorimeter, you have to consider the calorimeter. There is no mass component in calculating the heat lost to the calorimeter, because you cannot have half of a calorimeter, or one third, or five eighths. Since q(gain)=q(lost) and q lost is now to BOTH the water and the calorimeter, the q(gain)=q(H2O) + q(cal). Q(cal) = c(cal) x change in temperature.How is the change in enthalpy effected if the reaction is reversed?If the reaction is reversed, for example, if liquid water froze into solid water, and the reaction was reversed and the ice was melted, the change in enthalpy would switch signs. Enthalpy change is proportional to the equation. If you flip the equation the positive/negative sign also changes.What is the enthalpy when 2.63g P(s) reacts with excess Br2(l)?2.63 g P(s) x (1 mol P(s) / 30.97 g P(s)) x (-243 kJ/ 2 mol P(s)) = -10.3 kJLecture 16 (February 25)Find the Change in Enthalpy for NH3(g) + HCL(g)  NH4Cl(s).Given:1) ½N2(g) + 3/2H2(g)  NH3(g) ∆H=45.9kJ2) ½H2(g) + ½ Cl(g) HCl(g) ∆H=-92.3kJ3) ½ N2(g) + 2H2(g) + ½ Cl2(g)  NH4Cl ∆H=-314.4kJFlip 1, so NH3 is a reactant (also flip ∆H sign)NH3(g)1/2N2(g) + 3/2 H2(g) ∆H=45.9Flip 2, so HCl is a reactant (also flip ∆H sign)HCl(g)1/2H2(g) + ½Cl2(g) ∆92.3kJMAKE SURE EQUATIONS MATCH.Reactants: NH3(g) + HCl(g) + 1/2N2(g) + 2H2(g) + ½Cl(g)Products: ½ N2(g) + 3/2H2(g) + ½ H2(g) + 1/2Cl2(g) + NH4Cl(s)THEY MATCH!Add up 1-3 so they balance/cancel out to the targetDo the same manipulations to ∆H. ∆H overall = ∆H1 +∆H2 + ∆H345.9kJ + 92.3 kJ + (-314.4) kJ = -176.2 kJLecture 17 (February 27)What kind of reactions can you find how much energy there is per mole of fuel reacted?Heat of combustion is the type of reaction which tells you the energy per mol fuel reacted.Find the change in enthalpy of the equation: NH3(g) + HCL(g)  NH4Cl(s) ∆H=?1/2 N2(g) + 3/2H2(g)  NH3(g) ∆Hºf = -45.9kJ/mol½ H2(g) + ½ Cl2(g) HCl(g) ∆Hºf= -92.3kJ/mol½ N2(g) + 2H2(g) + 1/2Cl2(g)  NH4Cl(s) ∆Hºf= -314.4 kJ/mol∆Hºrxn = Σmx ∆Hºf(products) –Σn x ∆Hºf(reactants)∆Hºrxn= [(1mol NH4Cl)(∆Hºf NH4Cl)] – [(1mol NH3)(∆Hºf NH3) + (1mol HCl)(∆HºfHCl)]∆Hºrxn= [(1mol)(-314.4kJ/mol)] – [(1mol)(-45.9kJ/mol) + (1mol)(-92.3kJ/mol)]∆Hºrxn = -176.2 kJUse ∆Hºf values to calculate ∆Hºrxn for:4Al(s) + 3MnO2(s)  2Al2O3(s) + 3Mn(s)∆Hºf kJ/mol:Al = 0MnO2 = -520.9Al2O3 = -1676Mn = 0[(2mol)(-1676)] – [(3mol)(-520.9)] = -1789.3 kJWhat is Quantum Mechanics?The theory that explains the fundamental nature of energy and matter and accounts for atomic structureLecture 18 (March 2)Calculate the Frequency of LiCl emission at 680 nm.3.00 x 10^8 m/s = 680 nm x V3.00 x 10^8 m/s = 6.8 x 10^-7 m x V(3.00 x 10^8 m/s )/6.80 x 10^-7 m = 4.41 x 10^14 HzWhat is a quantum?A quantum is a fixed amount.Calculate the energy associated with Violet and Red lightViolet Light (λ=400 nm)Red Light (λ=700nm)E=hc/λ Violet:E=(6.626 x 10^-34 Js)(3.00 x 10^8 m/s) / (4.00 x 10^-7m) = 4.97 x 10^-19 JRed:E=(6.626 x 10^-34 Js)(3.00 x 10^8 m/s) / (7.00 x 10^-7 m) = 2.84 x 10^-19 JLecture 19 (March 4)When the change in E is negative, the atom absorb or emit energy?When E is negative, the atom emits energy. Also known as when N(final < N(initial)Calculate ∆E for transition (movement of e- between the states) from n=3 to n=2 in a H atom.-2.18x10^-18J[(1^2/2^2) – (1^2/3^2)] = ∆E-2.18 x 10^-18J(1/4-1/9)=-3.0278 x 10^-19 J/atomConvert J/atom  KJ/mol.2.18 x 10^-18/1atom x 6.022 x 10^23 atoms/1mol x 1 KJ/1000J = 1.31 x 10^3 KJ/molLecture 20 (March 6)Which sets of QN are allowed and if not, why?N=3 l=3 m(l)=0NO l cannot equal 3N=4 l=3 m(l)=4NO m(l) cannot equal 4N=2 l=0 m(l)=0Yupp totally