15). Classify each of these substances as an element, a compound, or a mixture.
a). A sample of “laughing gas” (dinitrogen monoxide, also called nitrous oxide)
b). Steam coming from a pan of boiling water
c). A bar deodorant soap
d). A sample of copper
e). A cup of mayonnaise
f). The helium filling a ballon
In: Chemistry
Every weak acid has the following unique characteristic(s):
a. at the 50% titration point the pH = pKa
b. the best buffering occurs +/- one pH unit of the pKa
c. the change in pH with added acid or base is the least when pH = pKa
d. the shape of the titration curve is essentially the same for all weak acids
e. all of the above
If the pH of a buffer with a pKa of 6 changes from pH 6 to 7 how does the [A-]/[HA] ratio change:
a. from 1/10 to 1/1
b. from 10/1 to 1/1
c. from 1/1 to 1/10
d. from 1/1 to 10/1
e. from 1/10 to 10/15
If the hydrogen ion concentration of a solution is 10-5 M, what is the hydroxyl ion concentration:
a. 10-5
b. 10-1
c. 10-2
d. 10-9
e. 10-5
What is the pH of a buffer with a pKa of 5 when the ratio of [A-]/[HA] is 10/1:
a. 3
b. 4
c. 5
d. 6
e. 7
If the pH is 8 what is the pOH:
a. 8
b. 4
c. 6
d. 12
e. 1
In: Chemistry
Which carbohydrate is converted by the human body to glucose by conversion of a carbonyl to an enol, then back to a carbonyl?
In: Chemistry
How long does it take to deposit a coating of gold 1.00 um thick on a disk-shaped medallion 4.00cm in diameter and 2.00mm thick at constant current of 86A? The density of gold 19.3 g/cm3 and the gold is from an Au(III) solution. (answer in seconds please!)
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What is the pH of the titration solution when 25.0 mL of .200 M aqueous formic acid, HCO2H, is titrated with 50.0 mL of 0.100 M aqueous potassium hydroxide, KOH? The Ka for formic acid is 1.8x10-4.
A. 8.52
B. 7.00
C. 5.71
D. 8.29
E. 10.26
In: Chemistry
PT1. Oxygen and sulfur have similar chemical properties due to having six valence electrons. Both form molecules with two hydrogen atoms. Surprisingly, water (H2O) is a liquid, yet H2S is a gas, even though sulfur is much larger and heavier than oxygen. Why? Explain fully.
PT2.
The ion product of water, Kw=[H+][OH-] = 0 x10-14 (3 points)
In: Chemistry
1. To identify a diatomic gas (X2 ), a researcher carried out the following experiment: She weighed an empty 4.8-L bulb, then filled it with the gas at 1.60 atm and 29.0 ∘C and weighed it again. The difference in mass was 8.7 g . Identify the gas.
2.Aerosol cans carry clear warnings against incineration because of the high pressures that can develop upon heating. Suppose that a can contains a residual amount of gas at a pressure of 745 mmHg and a temperature of 35 ∘C . What would the pressure be if the can were heated to 1290 ∘C ?
In: Chemistry
In a constant‑pressure calorimeter, 55.0 mL of 0.820 M H 2 SO 4 was added to 55.0 mL of 0.360 M NaOH . The reaction caused the temperature of the solution to rise from 23.45 ∘ C to 25.90 ∘ C. If the solution has the same density and specific heat as water ( 1.00 g / mL and 4.184 J / ( g ⋅ °C), respectively), what is Δ H for this reaction (per mole of H 2 O produced)? Assume that the total volume is the sum of the individual volumes.
In: Chemistry
The spacing between absorption lines in the far infrared spectrum of H35Cl is 6.350 x 1011Hz. Assuming the Rigid Rotor Model, calculate the values of the moment of inertia and the bond length in H35Cl.
In: Chemistry
|
Just as pH is the negative logarithm of [H3O+], pKa is the
negative logarithm of Ka,
pKa=−logKa The Henderson-Hasselbalch equation is used to calculate the pH of buffer solutions:pH=pKa+log[base][acid] Notice that the pH of a buffer has a value close to the pKa of the acid, differing only by the logarithm of the concentration ratio [base]/[acid]. The Henderson-Hasselbalch equation in terms of pOH and pKb is similar.pOH=pKb+log[acid][base] |
Part A Acetic acid has a Ka of 1.8×10−5. Three acetic acid/acetate buffer solutions, A, B, and C, were made using varying concentrations:[acetic acid] ten times greater than [acetate], [acetate] ten times greater than [acetic acid], and [acetate]=[acetic acid]. Match each buffer to the expected pH. Drag the appropriate items to their respective bins. SubmitHintsMy AnswersGive UpReview Part Correct Part B How many grams of dry NH4Cl need to be added to 1.50 L of a 0.400 M solution of ammonia, NH3, to prepare a buffer solution that has a pH of 8.57? Kb for ammonia is 1.8×10−5. Express your answer with the appropriate units.
SubmitHintsMy AnswersGive UpReview Part Incorrect; Try Again; 5 attempts remaining PLEASE HELP ME ANSWER PART B |
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Given the molality of isoborneol is 0.701 mol/kg, what is the percent by mass of camphor in the product?
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The heat of fusion of ice is 6.00 kJ/mol. Find the number of photons of wavelength = 6.27 10-6 m that must be absorbed to melt 3.00 g of ice.
In: Chemistry
what is the pH of a solution that mixes 30.00 mL of 0.010 M Ch3oh with 30.00 mL 0.00750 M Nach3co2?
In: Chemistry
The triple point of ammonia is at 196.2 K and 49.42 torr. The
molar enthalpy change of vaporization is equal to 24.65 kJ
mol-1 at this temperature.
a. Find the normal boiling temperature of ammonia.
b. The actual boiling temperature is -33 ̊C. Find the average value
of the molar enthalpy change of vaporization for the range between
the triple point and the normal boiling temperature.
In: Chemistry
1. Which of the following alkyl halides would not be suitable to make a Wittig reagent
1-bromo-2-methylpropane
2-bromobutane
2-bromo-2-methylpropane
(Bromomethyl)cyclopentane
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