In drawing the structures in lab: what color represents carbon atoms according to the key in the procedure?

Black

In drawing the structures in lab: what color represents hydrogen atoms according to the key in the procedure?

White

In drawing the structures in lab: what color represents nitrogen atoms according to the key in the procedure?

Blue

In drawing the structures in lab: what color represents halogen (chlorine) atoms according to the key in the procedure?

Green

You have a sample of unknown concentration. The species you are evaluating has a molar absorbtivity of 15.08, the path length is exactly 1 cm and the absorbance is 0.917, calculate the concentration using the equation A=$bc.

0.917/15.08=C

0.0608=C

You create a calibration curve of Absorbance vs. Concentration using a set of standards. You calculate the trendline to be y=3.73x + 0.049.

If one of the solution you are testing has a concentration of 0.20M, what would you expect the absorbance to be?

A=$bc

0.049=$(1)(0.20)

$=0.245

Standard 3 consists of 0.050M CuSO4. When preparing Standard 4: You will combine 10mL of Standard 3 with 10mL of deionized water. What is the concentration of Standard 4.

M1V1=M2V2

(0.050M)(10mL)=M2(20mL)

0.025=M2

Write the balanced equation for the reaction of the active ingredient in Phillips' Magnesium with HCl.

Mg(OH)2 (s) + 2HCl (aq) > MgCl2 (aq) + 2 H2O (l)

Calculate the volume of 2.5 M NaOH needed to make 200mL of 0.1M NaOH.

M1V1=M2V2

(2.5M)V1=(0.1M)(200mL)

V1=8 mL NaOH

Give the IUPAC name of CH3COOH.

Ethanoic Acid or acetic acid

Write an equation showing how to convert between temperature in Celcius and Kelvin.

tK = tC + 273.15

tC= tK - 273.15

Write the equation showing how to convert between pressure in atmospheres and the pressure in mmHg.

atm x 760.0 mmHg/atm = mmHg

mmHg/760.0 mmHg/atm = atm

Ideally a graph should have a correlation coefficient of (R2) what number? What does a deviation from this number indicate?

Ideally a graph should have a correlation of R2=1. A deviation from this number may indicate data deviating from the trend indicating an error.

Explain why "roses are red".

Because mostly red wavelength of light reflect off the roses, while amounts of all wavelengths are absorbed by the roses.

You have a sample of unknown concentration. The species you are evaluating has a molar absorptivity of 11.02, the path length is exactly 1 centimeter and the absorption is 0.621, calculate the concentration using the equation A=$bc.

0.621=11.02(1cm)c

0.0564=c

You create a calibration curve of Absorbance vs. Concentration using a set of standards. You calculate the trendline to be y=1.23x+0.024. The 0.024 is the y intercept or the absorbance when the concentration is 0. What could have caused this value to be greater than 0?

Sample could be contaminated.

Is molarity of solution independent of temperature? Why or why not? Give a better concentration value for use. Defend your choice.

No, molarity of a solution is dependent of temperature as volume of solution is affected by temperature because volume is proportional to temperature. A better concentration value would be Molality is independent of temperature because mass of the solvent is measure in kG and mass is independent of temperature.

How do you properly label a container?

Chemical Name, Chemical Concentration, Date Prepared and Initials

A student who is standardizing the NaOH solution fills the buret with the NaOH solution but does not open the stopcock to fill the tip of the buret before starting the titration. Will the NaOH concentration determined from this titration be higher or lower than the actual concentration? Explain.

Lower because it will appear that more NaOH had been delivered to the KHP sample than what actually was because the air trapped in the buret was accounted for as NaOH solution distributed to the KHP solution.

List 2 possible sources of error in the analysis of an antacid experiment and for each indication whether the effect would be an erroneously high or low value for the neutralization capacity of the antacid.

Not dissolving KHP properly would give the error of a lower reading of NaOH and KHP concentrations because if the KHP had been homogenous more NaOH would have been added to neutralize.

Not stirring KHP solution with indicator continuously during neutralization may overshoot the endpoint thus causing a false high concentration of KHP and NaOH because more NaOH would have been added than needed for neutralization. A higher NaOH concentration would give the false error of a higher KHP concentration.

Calculate slope:

slope = -dHvap/R

R constant= 0.008314 kJ/molxK

y= mx + b

What are the main components of a graph?

Data points and labels, labels for the graph and units, legend, named Y vs. X, include axis scales that are appropriate, contain a line of best-fit and equation, be in scatter chart type.

Clausius-Claypyron Equation

LN (P2) = dHvap (1 - 1)

(P1) R T2 T1

List the important sources of error in Absorption Spectroscopy experiment and what effect would each have on the results.

Imperfections or contaminated cuvette - would cause the absorbance reported to be too high because less light was transmitted.

Not blanking between wavelengths would cause lowered absorbances at higher wavelength changes causing the Copper standard to be in error of testing the copper standards.

Mixing up samples/using Metal as the blank. Depending on the samples, the errors would be higher and lower than normal. The error would depend on how much light transmitted through the incorrect blank sample.

A student makes a solution for analysis by mixing 5.172g of Cu2SO4 into 500g H2O. The density of H2O at the temperature of the lab at the time the solution was made is 0.9926 g/mL. Calculate molarity, molality, mole fraction, and mass percent of the cooper I sulfate.

Molarity: 0.02318mol/0.5037L = 0.04602M Cu2SO4

Molality: 0.02318mol/0.5kg = 0.05m

Mole fraction: 0.02318/27.8 = 8.34 x 10^-4

Mass%: 5.172g/505.172g x 100 = =1.02%