Chem Lab 2 Final

If the reaction between a metal ion and a ligand gave off heat, what would be the sign of delta H? and would it be exothermic or endothermic? a. +delta H, exothermic b. -delta H, exothermic c. +delta H, endothermic d. -delta H, endothermic

-delta H, exothermic

If you make 10 mL of a 1.205E-6 M crystal violet solution, how much of the 8.002E-5 M crystal violet do you need to measure to make the more dilute solution?

.151 mL

If the pH is 6.5, what is the concentration of H30+?

3.16E-7M

If the [H3O+] concentration is 6.8E-5M what is the pH?

4.17

Examples of lewis acids we have used in lab

Ca2+ Ni2+ Cu2+

what is the retention factor equal to? (Rf)

Rf = distance sample traveled/distance to the solvent front

What is volumetric analysis?

Titration, then stoichiometry to find mols of unknown

What is Ion Exchange Chromotography?

a chromatography process that separates ions and polar molecules based on their affinity to the ion exchanger. The two types of ion chromatography are anion-exchange and cation-exchange.

You found in the 100.0 mL solution you have .00251 mol of H+ that was generated from the column using a 20.00 mL water sampleof Ca^2+. How many mols of Ca^2+ are present in the water sample? a. .00126 mol Ca^2+ b. .00502 c. .0126 d. not enough info

a. .00126 mol Ca^2+

You use an average volume of 11.65 mL of .00821 M EDTA to titrate against a 20.00 mL solution of Ca^2+. What is the concentration of he 20.00 mL Ca^2+ a. .004776 M b. .008200 M c. .009553 M d. .002388 M

a. .004776 M

IF you plot the concentration of crystal violet vs time and get a negative linear slope, what is the expected order of the reaction crystal violet? a. 0 b. 1 c. 2 d. 4

a. 0 order

How many acidic hydrogens does neutral eriochrome black T indicator have? a. 2 b. 6 c. 4 d. 1

a. 2

If you perform cation-exchange chromatography on a solution containing Mg^2+ ions, how many mols of H ions will be displaced by 1 mol Mg^2+? a. 2 b. 5 c. 3 d. 1

a. 2

You found that the 20.00 mL Ca^2+ water sample is .0243% Ca^2+ ion. What is the concentration of the Ca^2+ sample in ppm? a. 243 ppm b. .0972 ppm c. 2.43 ppm d. 6.075 E -4 ppm

a. 243 ppm

You found that the mass percent of Ca^2+ ions in your hard water sample is .2504%. What is the concentration in ppm? a. 2504 ppm b. 25040 ppm c. 1252 ppm d. .02504 ppm

a. 2504 ppm

What is the expected wavelength range for a solution that is yellow in color? a. 425-450nm b. 600-650nm c. 550-600nm d. 800-900nm

a. 425-450nm

What would be the expected conductivity of DI water? a. 54 uS/cm b. 936 uS/cm c. 1756 uS/cm d. 7 uS/cm

a. 54 uS/cm

What would be the expected conductivity of tap water? a. 554 uS/cm b. 15600 uS/cm c. 25 uS/cm d. 0 uS/cm

a. 554 uS/cm

What was the lewis acid in experiment 1? a. Ca^2+ b. EDTA c. Eriochrome Black T d. NaOH

a. Ca^2+

What is the primary standard used for the redox titration? a. KIO3 b. K2S2O3 c. KCl d. KI

a. KIO3

What was the primary standard used for the redox titration? a. KIO3 b. K2S2O3 c. KCl d. KI

a. KIO3

What are the units of the molar absorptivity constant ( squiggly e) in the kinetics experiment? a. L/molcm b. 1/cm c. cmmol/L d. there aren't units

a. L/molcm

If you perform anion-exchange chromotography on a solution containing Cl- ions, what ions will be in your eluate? a. OH- b. Cl- c. H+ d. N(CH3)3+

a. OH-

What is the observed color change when you use Eriochrome Black T as an indicator? a. Red --> Blue b. Black --> Yellow c. Colorless --> Pink d. No Color Change

a. Red --> Blue

What would happen if you added the starch too early in the redox titration? a. The starch-I3 complex would not be able to react with the thiosulfate and uncomplex and the solution would not turn colorless b. the starch would make the solution cloudy c. nothing would happen d. the solution would turn colorless automatically

a. The starch-I3 complex would not be able to react with the thiosulfate and uncomplex and the solution would not turn colorless

What does Ka stand for? a. acid dissociation constant b. cat dissociation constant c. base dissociation constant d. water acidity constant

a. acid dissociation constant

What would you expect the color change to be if we used phenolphthalein as out indicator when NaOH is added to our H+ solution? a. colorless --> pink b. red --> blue c. no color change d. pink --> colorless

a. colorless --> pink

what does it mean if a ligand is bidentate? a. it has two donor atoms and can bind to the central metal ion at two points b. it has one donor atom and can bind to the central metal ion at one point c. it makes things turn pretty colors

a. it has two donor atoms and can bind to the central metal ion at two points

In the thermochemistry lab what should your final units be? a. kJ/mol of metal ion b. J/g metal ion c. kJ metal ion d. *C/mol metal ion

a. kJ/mol of metal ion

What is the color of phenolphthalein in basic conditions? a. magenta b. colorless c. blue d. yellow

a. magenta

If our sample has a low affinity to the stationary phase and high affinity to the mobile phase, where do you expect it to be located on the TLC plate? a. near the top b. near the middle c. near the bottom d. not enough info

a. near the top

What indicator did you use in the ion-exchange chromotography titration? a. phenolphthalein b. eriochrome black T c. methyl blue d. EDTA

a. phenolphthalein

If the solution turns blue when using eriochrome black T as your indicator what does that mean? a. there aren't any metal ions present b. the solution is basic c. the solution is acidic d. there are metal ions present

a. there aren't any metal ions present

If the solution turns blue when using eriochrome black t as your indicator what does that mean? a. there aren't metal ions that would bind to eriochrome black T b. the solution is basic c. there are metal ions that would bind d. the solution is acidic

a. there aren't metal ions that would bind to eriochrome black T

What is the purpose of adding the buffer solution to the Ca^2+ solution? a. to deprotonate the acidic hydrogens in the EDTA so they can bind to Ca^2+ b. to protonate the acidic hydrogens in the eriochrome black T so it can bind to the Ca^2+ c. to change the charge of Ca to Ca^2+ d. because it tells us to

a. to deprotonate the acidic hydrogens in the EDTA so they can bind to Ca^2+

The reaction between metal ions and ligands is an example of a lewis acid-base reaction. a. true b. false

a. true

You used 10.53 mL of .0475M NAOH to titrate against a 20.00mL sample of 100.0 mL H+ solution that eluted from the ion exchange column. What is the number of mols of H+ in the 100 mL solution? a. .00100 mol b. .00250 mol c. .00500 mol d. not enough info

b. .00250 mol

How much of the EDTA Sodium salt (MM = 372.24 g/mol) do you need to weigh to make 50.00 mL of a .0100 M solution? a. .369 g b. .1860 g c. .18 g d. .186 g

b. .1860 g

If the distance that spot D traveled was 21.5mm and the distance the mobile phase traveled was 54.2 mm what is the Rf? a. .397 mm b. .397 c. 2.52 d. 2.52mm

b. .397

From your data T=22.1 and T=40.1 what is the change in temp and is the reaction exothermic or endothermic? a. 18 exo b. 18.0 exo c. 18 endo d. 18.0 endo

b. 18.0 exo

What is the molar ratio between Ca+ and EDTA? a. 1:3 b. 1:1 c. 2:1 d. 4:2

b. 1:1

What is the expected wavelength range for a solution that is blue? a. 425-450nm b. 600-650nm c. 550-600nm d. 800-900nm

b. 600-650nm

What is the molar ratio of S2O32- with respect to IO3-? a. 1:3 b. 6:1 c. 1:6 d. 2:5

b. 6:1

After adding 20.00 mL of a Ca^2+ water solution to a column that has cation-exchange resin in it, what would you expect to eluate in this separation? a. OH- b. H+ c. Cl- d. Ca^2+

b. H+

If you perform ion-exchange chromatography, with anion-exchange resin, on a solution containing Cl- ions, what ions will be in your eluate? a. Cl- b. OH- c. N(CH3)3+ d. H+

b. OH-

To make a calibration curve of a series of dilutions what do you need to plot? a. absorbance v wavelength b. absorbance v concentration c. concentration v wavelength d. concentration v time

b. absorbance v concentration

when is the pKa = pH? a. at the equivalence point b. at the .5 equiv point c. at pH = 2 d. at pH = 10

b. at the .5 equiv point

What indicator did you use to find Ka in the spectroscopy lab? a. methylene blue b. bromothyl blue c. phenolphthalein d. bromocresol green

b. bromothyl blue

What is the defining characteristic of a Lewis Acid? a. electron pair donor b. electron pair acceptor c. proton acceptor d. proton donor

b. electron pair acceptor

What is the defining characteristic of a Lewis base? a. electron pair acceptor b. electron pair donor c. proton donor d. proton acceptor

b. electron pair donor

A cation exchange column is not regenerated after being used. How might this affect the Ca2+ determination for the next set of students? a. it would not affect their calculations b. it is possible that not enough H+ remains to exchange with all of the Ca2+ c. it is possible that there will be too much H+ that will elute

b. it is possible that not enough H+ remains to exchange with all of the Ca2+

What does each symbol represent in the q=mCdeltaT? a. molarity, celcius, change in temperature b. mass(g), Csp, change in temp c. g Joules celsius g d. mols, celsius, T

b. mass(g), Csp, change in temp

If the sample has a high affinity to stationary phase and a high affinity to mobile phase where do we expect it to be located on TLC plate? a. near the top b. near the middle c. near the bottom d. not enough info

b. near the middle

What does NMR stand for? a. no more rhinos b. nuclear magnetic resonance c. nuclei machine retention d. non matching rubbish

b. nuclear magnetic resonance

To create a titration curve what do you need to plot? a. pH vs concentration of titrant b. pH vs volume of titrant used c. pH vs. mass of titrant d. pH vs molecular mass

b. pH vs volume of titrant used

What are two things every chromatography has in common? a. solvents and developing jars b. stationary and mobile phase c. silica phase and mobile phase d. stationary phase and solvent

b. stationary and mobile phase

What is the purpose of the indicator in a titration? a. to see pretty colors b. to find the mols of unknown by seeing the endpoint of a reaction c. because we are told to have an indicator

b. to find the mols of unknown by seeing the endpoint of a reaction

If all the HCl was not properly rinsed out of the cation-exchange column, how would that effect the concentration of Ca2+? a. would not change b. would appear to be higher c. would appear to be lower d. would appear to be zero

b. would appear to be higher

If you perform cation-exchange chromotography on a solution containing Fe^3+ ions, how many mols of H+ ions will be displaced by 1 mol Fe^3+? a. 2 b. 5 c. 3 d. 1

c. 3

In the Ka experiment spectrophotometric analysis is being used. What is the range of wavelength you read the solutions over? a. 350- 900 nm b. 200 - 900 nm c. 350 - 700 nm d. 200 - 700 nm

c. 350 - 700 nm

How many acidic hydrogens does neutral EDTA have? a. 2 b. 6 c. 4 d. 1

c. 4 (on each OH)

What was the secondary standard used for the redox titration? a. NaIO3 b. KI c. Na2S2O3 d.KIO3

c. Na2S2O3

If trying to neutralize 10.00mL of .2M monoprotic acid using .1M NaOH how much NaOH do you expect to use? a. about 5mL b. about 10mL c. about 20 mL d. not enough info

c. about 20 mL

You are doing an acid base titration and phenolphthalein is the indicator. Where should the acid and base be? a. doesn't make a difference b. base should be in flask, acid in buret c. base should be in buret, acid in flask

c. base should be in buret, acid in flask

What are the colors of bromothymol blue is basic and acidic conditions? a. red and blue b. blue and purple c. blue and yellow d. colorless and pink

c. blue and yellow

What is the observed color change with phenolphalein as the indicator when titrating with a base? a. red --> blue b. black --> yellow c. colorless --> pink d. no color change

c. colorless --> pink

What is the slop of the beers law calibration curve equal to? a. A b. 1 c. e x l d. c

c. e x l

If you cool the solutions of both NaOH and crystal violet below room temp, how would you expect the rate of the color change to be compared with the rate using room temp solutions? a. more quickly b. same rate c. more slowly d. no color change

c. more slowly

If our sample has a high affinity to the stationary phase on the TLC plates and low affinity to the mobile phase where do you expect it to be located? a. near the top b. near the middle c. near the bottom d. not enough info

c. near the bottom

What is the indicator youused in the potentiometric titration? a. brothymol blue b. starch c. phenolpthalein d. methylene blue

c. phenolpthalein

If there are three protons on a carbon atom adjacent to a CH2 group, what would you expect the splitting/multiplicity of the CH2 group to be? a. singlet b. doublet c. quartet d. triplet

c. quartet

What indicator will you use in the redox titration? a. phenolphthalein b. eriochrome black T c. starch d. methylene blue

c. starch

If the solution turns red when using eriochrome black T as your indicator what does that mean? a. there aren't metal ions in the solution b. the solution is basic c. there are metal ions in the solution d. the solution is acidic

c. there are metal ions in the solution

If the solution turns red when using eriochrome black T as your indicator what does that mean? a. there aren't any Ca2+ or Mg2+ ions present b. the solution is basic c. there is Ca2+ or Mg 2+ present d. the solution is acidic

c. there is Ca2+ or Mg 2+ present

If you mass out .186g of EDTA (372.24 g/mol) and make it up to 50.00mL what is the molarity? a. .0100M b. .01M c. .009993M d. .00999M

d. .00999M

If you plot the natural log of the concentration of crystal violet vs time on a graph and get a negative linear slope, what is the expected order? a. 4th b. 0 c. 2nd d. 1st

d. 1st order

What color change do you see when you add NaOH to crystal violet? a. colorless --> pink b. purple --> blue c. red --> blue d. purple --> colorless

d. purple --> colorless

Examples of leis bases we have used in lab

eriochrome black T, EDTA, ethylenediamine

Is the reaction between Ni2+/Cu2+ and ethylenediamine exothermic and endothermic?

exothermic

What is the HOMO in MO theory?

highest occupied molecular orbital

Did metal ions in the thermochemistry lab act as a lewis acid or base?

lewis acid

What is the LUMO in MO theory?

lowest occupied molecular orbital