What is the precentage by mass of oxygen in CaCO3?
In: Chemistry
Calculate the pH of a 0.89 M methylamine solution.
In: Chemistry
In a procedure developed to determine the percent zinc in post 1982 pennies, 50 mL of an HCl solution was used to react (dissolve) all of the zinc in the penny. To ensure complete reaction, the solution contains twice as many moles of HCl that is usually needed. What concentration of HCl should be used? What is the amount in moles of excess (unreacted) HCl in solution? How many moles of NaOH would be needed to completely react with all of the excess HCl?
To determine the percent zinc in the penny, the excess was titrated with NaOH. determine the concentration of NaOH needed if you want to use approx 25 mL of NaOH to titrte the excess HCl.
In: Chemistry
calculate the % difference of the 0.5133g and 0.5275 g of struvite from the two water samples in question a. ----> two 10.0 Ml water samples were taking The procedure in this experiment is followed to determine the phosphate concentration. What would be the average phosphate concentration in the solution be( in units of molarity) if the student obtained 0.5133g and 0.5275g of struvite using gravimetric analysis? show all work assume this procedure precipitates out all of the phosphate from the sample in form of struvite
In: Chemistry
Dr. Dahm is trying to generate CO2(g) by reacting an acid with calcium carbonate. If he pours 389 mL of a 1.6 M solution of H2SO4 into a flask that contains 69.5 g of CaCO3. If the temperature is 30 °C and the pressure is 0.984 atm calculate the volume of CO2(g) produced.
H2SO4 + CaCO3 CO2(g) + CaSO4(aq) + H2O(l)
In: Chemistry
What is the molarity of 109mL of a 17.2% NaCl solution?
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For the reaction shown, compute the theoretical yield of product (in grams) for each of the following initial amounts of reactants.
2Al(s)+3Cl2(g)→2AlCl3(s)
Part B
7.8 g Al, 25.2 g Cl2
Express your answer using three significant figures.
Part C
0.230 g Al, 1.10 g Cl2
Express your answer using three significant figures.
In: Chemistry
1. The Kaof iodic acid (HIO3) at 25 °C is 1.6*10-1. What is the Kb of iodate (IO3-) at this temperature?
b. Use the information in the first question to calculate the pH of a 0.10 M solution of iodic acid at a temperature of 25 °C?
c. Use the information in the first question to calculate the pH of a solution obtained by combining 20.0 mL of 0.10 M iodic acid and 10.0 mL of 0.1 M sodium hydroxide (NaOH).
d. Use the information in the first question to calculate the pH of a solution obtained by combining 20.0 mL of 0.10 M iodic acid and 20.0 mL of 0.1 M sodium hydroxide.
Appriciate it!
In: Chemistry
Compare the Peng-Robinson vapor pressures to the experimental vapor pressures (respresented by Antoines constants) for n-Hexane
In: Chemistry
Compare the standard molar entropy for three common forms of iodine in different states ofmatter. Explain the trend in the values; why are they different?
S
In: Chemistry
1) You are given an unknown containing
KClO3.
Following the procedure in your manual, you obtain the following
fictional data
Note! For this problem use the given
(allbeit incorrect) vapor pressure of
water
| Mass of empty test tube | 54.5679 g |
| Mass of test tube + unknown | 54.8523 g |
| Mass of test tube + unknown + MnO2 | 54.9786 g |
| Mass of erlenmeyer flask with residual water | 308.81 g |
| Mass of erlenmeyer flask filled with water | 364.23 g |
| Atmospheric pressure | 754.9 mmHg |
| Temperature of water | 38.5 °C |
| Partial pressure of water at 38.5 | 37.94 mmHg |
| Mass of test tube + Residue after heating | 54.9032 g |
| Density of water | .996 g/mL |
| A) Molar volume of Oxygen | |
| (a) Volume of Oxygen collected | _______________ mL |
| (b) Partial pressure of dry oxygen | _______________ mmHg |
| (c) Volume of oxygen corrected to STP | _______________ mL |
| (d) Mass of oxygen produced | _______________ g |
| (e) Moles of oxygen gas produced | _______________ mol |
| (f) Calculated molar volume at STP | _______________ L/mol |
| B) Per cent KClO3 in unknown | |
| (g) Mass of unknown used | _______________ g |
| (h) Moles of KClO3calculated from moles O2 | _______________ mol |
| (i) Mass of KClO3 in unknown calculated from moles O2 | _______________ g |
| (j) Per cent KClO3 in unknown | _______________ % |
| C) Residual "KCl??" from
UNKNOWN Residual "KCl??" is what is left in the tube after heating except for the MnO2 |
|
| (k) Mass of residual KCl? produced from UNKNOWN | _______________ g |
| (l) Theoretical yield of KCl if UNKNOWN is 100% KClO3 | _______________ g |
| (m) % Yield of "KCl" based on k and l above | _______________ % |
| the actual vapor pressure of water at 38.5 °C | _______________ mmHg |
| WARNING...Do not use this number in problem 1 |
3) Know....
How accurately you will measure the volumes and
weights?
How accurately you will be able to measure molar volume, %
KClO3
What is the function of MnO2, the leveling tank
When do you use the Triple Beam Balance and the Analytical Balance
and why.
Then think how would your results be affected
IF...:
You started with a wet test tube?
You made an error in one or more of your weighings?
You made an error of 1 cm in using the leveling tank?
In: Chemistry
Calculate the energy difference for a transition in the Paschen series for a transition from the higher energy shell n=6. Express your answer to four significant figures and include the appropriate units
In: Chemistry
A sample solution of [(+/-)-Co(en)3]I3 (with no impurities) is found to have [α]D = +77o, whereas a pure enantiomer would give a value of [α]D = +89o. Calculate the exact percentage of (+) and (-) isomers present in the sample solution. (note: you must first reason whether the rotation value indicates the total amount of + isomer or the enantiomeric excess).
In: Chemistry
Two chemicals are present in the same sample, where compound A is the analyte of interest and B is a possible interfering agent. It is known that A has a distribution ratio of 26.7 at pH = 7.0 when extracted from water with toluene. Compound B has a distribution coefficient ratio of 0.24 under the same conditions.
A) What percent of each compound will be extracted from a 100.0 mL sample of water when using 20.0 mL of toluene in a single-step extraction?
B) What percent of A and B will be extracted after two, three and four extractions if each extraction step uses a fresh 20.0 mL portion of toluene?
C) Describe how the recovery and purity of compound A will change as the
number of extractions increases in this sample.
In: Chemistry
compare column, thin-layer, and gas chromatography in terms of mobile phase and stationary phase
In: Chemistry