A buffer that contains 0.592 M base, B, and 0.286 M of its conjugate acid, BH+, has a pH of 8.87. What is the pH after 0.0020 mol of HCl is added to 0.250 L of the solution?
In: Chemistry
1.)Describe the effect of increasing the concentration of the reactants on the rate of a reaction.
2.)The exponents in a rate law have no relationship to the coefficients in the overall balanced equation for the reaction. Give an example of a balanced equation and the rate law for a reaction that clearly demonstrates this.
3.)Compare the half-life equations for a first-order and a second-order reaction. For which reaction order is the value of the half-life independent of the reactant concentration??
In: Chemistry
| Na2SO4(mL) | BaCl2(mL) |
BaSO4(g) Actual Grams |
BaSO4(g) Actual Grams | |
| 8 | 2 | 0.58 | 0.54 | |
| 8 | 4 | 1.59 | 2.03 | |
| 8 | 6 | 2.45 | 2.39 | |
| 8 | 8 | 1.97 | 2.13 | |
| 8 | 10 | 1.61 | 2.08 | |
| 8 | 12 | 1.84 | 2.59 | |
| Can someone please help me in calculating the theoretical grams from this information. thanks. |
In: Chemistry
The two pKas of sulfurous acid (H2SO3) are 1.81 and 6.91, respectively. The predominant species at pH = 9 is: (Question from "Cracking the MCAT, 2010-2011 edition" by The Princeton Review)
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1. H+ |
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2. HSO3− |
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3. SO32− |
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4. H2SO3 |
In: Chemistry
Phosphine (PH3) decomposes into phosphorus and
molecular hydrogen:
4PH3(g) → P4(g) + 6H2(g)
Experiments show that this is a first-order reaction, with a rate
constant of 0.0173 s-1 at 650°C. Identify each of the
following statements about this reaction as true or false. (Use the
drop-down menu and select "True" or "False" for each. You must get
all 4 correct.)
True/False The mechanism for this reaction must involve
two or more elementary steps.
True/False The activation energy for the reaction cannot
be determined without additional data.
True/False The rate constant would be smaller than
0.0173 s-1 at 500°C.
True/False The rate-determining step for the reaction
could involve a bimolecular collision between two PH3
molecules.
In: Chemistry
Chemical Engineering Problem:
A vapor composed of 0.25 mole fraction ethanol and 0.75 mole fraction acetic acid at 120.0 mmHg (absolute), is in equilibrium with a liquid phase also composed of ethanol and acetic acid. Assume that the liquid is an ideal solution and apply Raoult\'s law to find the following. What is the temperature of the liquid?
What is the Temperature of the fluid? _____C
What are the mole fractions of the liquid phase?
XE=_____mol ethanol/mol
XA=_____mol acetic acid/mol
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4 liter sealed container contains water vapour at 0.4 atm and 90°C. a) What is the dew point of the vapour? b) Determine the percentage of the vapour that will condense if the system is cooled to 50°C.
In: Chemistry
Part A
Determine the [H3O+] of a 0.250M solution of formic acid.
Express your answer using two significant figures.
[H3O+] = ???
Part B
Determine pH of this solution of formic acid.
Express your answer to two decimal places.
pH=???
In: Chemistry
500.0 mL of 0.140 M NaOH is added to 595 mL of 0.200 M weak acid (Ka = 2.29 × 10-5). What is the pH of the resulting buffer? HA (aq) + OH (aq) ---> H2O (L) + A (aq)
In: Chemistry
What compound is used as a standard for location of NMR signals?
Select one:
a. acetone, CH3COCH3
b. silicon grease
c. water
d. deuterated water, D2O
e. deuterated chloroform, CDCl3
f. trimethylsilane, (CH3)4Si
g. chloroform, CHCl3
In: Chemistry
Menthol is a crystalline substance with a peppermint taste and odor. When 1.22 g of menthol is dissolved in 25.0 g of cyclohexane, the freezing point of the solution is lowered by 6.52 °C. The freezing point and Kf constant for cyclohexane can be found here. Calculate the molar mass of menthol.
In: Chemistry
A 9.65-L container holds a mixture of two gases at 31 °C. The partial pressures of gas A and gas B, respectively, are 0.171 atm and 0.877 atm. If 0.200 mol of a third gas is added with no change in volume or temperature, what will the total pressure become?
In: Chemistry
The flask shown here contains 1.04 g of acid and a few drops of phenolphthalein indicator dissolved in water. The buret contains 0.280 M NaOH. When titrated the end point of the solution is 26 mL.
What volume of base is needed to reach the end point of the titration?
Assuming the acid is monoprotic, what is its molar mass?
In: Chemistry
outline a lab experiment which could be done in order to determine delta H, delta G and dellta S of dissolution of Urea
In: Chemistry
Einstein predicted that the mean squared displacement of small particles due to diffusion (random motion, executed in small, discrete steps) would increase linearly with time. Prove it in a simple way.
In: Chemistry