Suppose we titrate 20.0 mL of 0.20 M of formic acid (HCHO2, Ka= 1.8 x 10^-4) with 0.20 M KOH. Calculate the pH for the following:

a) before any base is added

b) when half of the formic acid has been neutralized

c) after a total of 15 mL has been added

d) at the equivalence point

Some people have an allergic reaction to the food preservative sulfite (SO32−). Sulfite in wine was measured by the following procedure: To 50.0 mL of wine were added 5.00 mL of solution containing (0.8043 g KIO3 + 5 g KI)/100 mL. Acidification with 1.0 mL of 6.0 M H2SO4 quantitatively converted IO3− into I3−. The I3− reacted with SO32− to generate SO42−, leaving excess I3− in solution. The excess I3− required 12.86 mL of 0.04818 M Na2S2O3 to reach a starch end point. Find the concentration of sulfite in the wine. Express your answer in mol/L and in mg SO32− per liter.

1. a)Which of the following statements are TRUE for a buffer solution.
Select all that are True.
_ A buffer can be prepared by combining a weak acid and its conjugate base."
_ A buffer resists changes in pH.
_ When a strong acid is added to a buffer, it reacts with the conjugate base which slightly increases the pH of the solution.

3. Given the following data set: Indicate where the buffere capacity has been exceeded.

The buffer capacity was exceeded when_______mL of NaOH was added?

why does the measurement of fluorescence data require a more intense source of uv/visible spectroscopy? specific. b) what is the typical source for spectofluorometer? c) for the photomuiltiplier transducer what is the mode off operation used signal to noise?

How to convert 100 micrograms per milliliter to 10 nanomolar?

Starting from a symbolic expression of the Second Law of Thermodynamics, show how arguments based purely upon considerations of entropy lead to the formalism which we call Gibbs

A 0.1936 gram sample of primary standard K2Cr2O7 was dissolved in water, the solution was acidified, and after the addition of KI, the titration of liberated I2 required 33.61 ml of Na2S2O3 solution. Calculate the molarity of the thiosulfate solution.

1.20 g of an unknown liquid is placed into a 2.3 L container under vacuum. (No gases present.) The liquid completely evaporates at 25.03°C and becomes a gas with a pressure of 325.3 torr. What is the molar mass of the the unknown substance?

The data to the below were collected for the bovine carbonic anhydrase-catalyzed reaction described by

CO2 (aq) + H2O (l) -->H+ (aq) + HCO3- (aq)

Use these values to determine the value of KM, the Michaelis-Menten constant. Answer the four parts below.

a) If you were to plot this data to graphically determine Rmax and KM using a Lineweaver-Burk plot, what would you plot for the following data? If you would plot the original data, enter the original value in the corresponding blank.

[CO2] (mmol * L^-1) graph as R (ݵmol * L^-1 * s^-1) graph as

1.25--> ________ 28.74 --> ________

20.00--> ________ 155.59 --> ________

b) Calculate the slope using the data points from part (a). Then determine the y-intercept using the second point.

Slope= _______ s y-intercept= ___________ L * s * mmol^-1

c) Use the y-intercept to calculate Rmax.

Rmax=___________ mmol * L^-1 * s^-1

d) Use Rmax and the slope to calculate Km.

Km=___________ mmol * L^-1

Using Crystal Field Theory explain how d orbital splitting arises in an octahedrarl field.

Construct a table to show how to make the standard solutions from serial dilution, starting with a stock solution of 1000 ppm in 100 mL volumetric flask.

Use 1000 ppm standard soltuions of Co, Cr, Pb, Cd, and Zn to prepare the following five standard solutions with 10% HNO₃ in 100 mL volumetric flask:

Std 1: 100 ppm of Co, Cr, Pb, Cd, Zn

Std 2: 50 ppm of Co, Cr, Pb, Cd, Zn

Std 3: 10 ppm of Co, Cr, Pb, Cd, Zn

Std 4: 5 ppm of Co, Cr, Pb, Cd, Zn

Std 5: 1 ppm of Co, Cr, Pb, Cd, Zn

The heat energy associated with a change in temperature that does not involve a change in phase is given by

q=msΔT

where q is heat in joules, m is mass in grams, s is specific heat in joules per gram-degree Celsius, J/(g⋅∘C), and ΔT is the temperature change in degrees Celsius. The heat energy associated with a change in phase at constant temperature is given by

q=mΔH

where q is heat in joules, m is mass in grams, and ΔH is the enthalpy in joules per gram.

Physical constants

The constants for H2O are shown here:

Specific heat of ice: sice=2.09 J/(g⋅∘C)

Specific heat of liquid water: swater=4.18 J/(g⋅∘C)

Enthalpy of fusion (H2O(s)→H2O(l)): ΔHfus=334 J/g

Enthalpy of vaporization (H2O(l)→H2O(g)): ΔHvap=2250 J/g

Part A

How much heat energy, in kilojoules, is required to convert 63.0 g of ice at −18.0 ∘C to water at 25.0 ∘C ?

Express your answer to three significant figures and include the appropriate units.

Part B

How long would it take for 1.50 mol of water at 100.0 ∘C to be converted completely into steam if heat were added at a constant rate of 15.0 J/s ?

Express your answer to three significant figures and include the appropriate units.

1.2 Which strategy is not a viable “green” option in the chemical industry?
(a) Using catalysts to reduce energy consumption
(b) Reducing the number of steps in a multistep synthesis
(c) Maximizing yield
(d) Running the reaction on a smaller scale

Why would atomic absorption spectroscopy be less sensitive to low source temperature, assuming efficient atomization?