CHM 1045 Lab Exam with Verified Answers 2024

1 lb = _______ kg - 0.454 5 steps of creating a Lewis structure - 1. calculate total number of valence electrons available 2. determine which will be the central atom 3. arrange atoms symmetrically around the central atom 4. place bonds/electrons around the atoms until the octet rule is satisfied for each atom, using double or triple bonds if necessary 5. show any charges on the molecule by using brackets and writing the charge in the top right corner outside the brackets acid + base --> - a salt + water after the extraction with dichloromethane is performed, the layers separate, and you filter the dichloromethane layer out of the separatory funnel, how do you know how much caffeine is in the solution? - Put it on a hot plate to evaporate the dichloromethane. Caffeine will stay in the beaker amount of Zn needed to make the balloon float, given that 475 mL of H2 (g) is produced from 1.85g Zn(s) - (475mL/desired volume) = (1.85g/mass Zn needed) as charges of ions increase, lattice energy __________ - increases As temperature decreases, density of air ____________ - increases atomic radii conversion - 1 Å = 1 × 10^−10 m = 100 pm characteristics of heating/cooling curves - y-axis = temperature x-axis = time heating curve - initial sharp drop in temperature, gradually warms back upcooling curve - initial sharp increase in temperature, gradually cools back down final temp is point of its largest change in temperature color of AgI, silver iodide - white color of CdS - orange color of CuS - blue (experimentally darker) color of Fe(OH)3 - brownish amber color of Ni(OH)2 - turquoise color of PbI2, lead iodide - yellow (dark brown in experimentation) compounds containing a group 7 element - soluble, except those with Ag+, Hg+, or Pb^2+ compounds containing an SO4^2- ion - soluble, except those containing Ba^2+, Sr^2+, or Pb^2+ compounds that contain a group 1 element - soluble compounds that contain the NH4+ ion - soluble compounds that contain the NO3- or C2H3O2- ion - soluble core electrons - electrons corresponding with the closest previous noble gas (i.e. all except those in the highest energy shell, inner shell electrons)covalent bonds form based on - the sharing of electrons that provides an octet of electrons for each describe the color scale on pH paper and the limitations this presents - pH 1 (very acidic) = red 3 = orange 4 = yellow 6/7 = green 9 = blue 11 (very basic) = violet color scale is not very detailed/specific, so this only allows for whole number estimates desired balloon volume = - mass of balloon/density of air dew point - critical temperature for cloud formation; air temperature must fall below this point for a cloud to form effusion - the movement of a gas through a pore or capillary into another gaseous region or into a vacuum elements and atoms without charge in their elemental state have an oxidation number equal to - zero endpoint of acid-base titration - moles acid = moles base energy released or absorbed in the dissolution of a compound comes from - 1. bonds of the compound must be broken (endergonic) 2. bonds of the solvent must be broken or disrupted (endergonic) 3. bonds or interactions must form between the solute and solvent (exergonic) enthalpy of solution - {delta}Hsol