Reaction 1: NaOH(s)--> NaOH (aq)
Reaction 2: NaOH(s) + HCl (aq)--> NaCl(aq)+H2O(l)
Reaction 3: NaOH(aq) +HCl (aq) --> NaCl (aq) + H2O (L)
1) Describe each reaction as endothermic or exothermic and explain your reasoning.
2) Examine the chemical equations for the three reactions. Determine their relationship in a way that is consistent with Hess's Law. (i.e. verify that Hess's Law is upheld. Reaction 3 is the target equation).
3) Why is heat a stoichiometric quality?
4) Just what IS a heat of solution?
In: Chemistry
At a temperature of 25ºC the following cell shows a potential of 0.7585 V: Cd/CdCl2 (0.01 M) II AgCl (sat)/Ag
(i) calculate the standard electromotive force of the cell; (ii) Calculate the mean activity coefficients in the CdCl2 solution.
In: Chemistry
At a temperature of 25ºC the following cell shows a potential of 0.7585 V: Cd/CdCl2 (0.01 M) II AgCl (sat)/Ag (i) calculate the standard electromotive force of the cell; (ii) Calculate the mean activity coefficients in the CdCl2 solution.
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Given the mole of air as 9.2x10-5 mol, the volume of water vapor, after correction, is 5.0 mL while the temperature is 75 oC, what is the vapor pressure of water in mmHg if the atmospheric pressure (Patm ) is 0.989 atm.
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Explain why it is necessary to select only one wavelength to pass through the sample (i.e. why don’t we just shine white light into the sample and measure the amount of light that passes through?)
In: Chemistry
In this part of today's experiment you will produce cyanotypes using watercolor paper. Directions 1. Each student should obtain a piece of 4” x 5” watercolor paper. Work with ONE partner. 2. Each pair should prepare the following solution in a 250 mL beaker. 1.2g ferric ammonium citrate 0.6g potassium ferricyanide 20 mL of water 3. Stir until dissolved and describe the color of the mixed solution. ______________________ 4. Place the paper in one of the plastic trays under the hood. Using a flat foam brush, coat one side completely with the solution. Wipe first in one direction and then a second time at a right angle to the first direction. 5. CAREFULLY dry the paper using a hot air gun, or place in the oven in the Prep room. 6. When dry, print the dry paper by clipping a large negative image on top of the paper and exposing it to sunlight (outside, if it’s sunny) or a UV light source (inside). 7. When the exposed regions of the paper are changed in color to a deep blue-green, unclip and remove the negative. 8. Wash the paper with a gentle stream of tap water to remove the soluble unreacted light sensitive chemicals. 9. Dry the blueprints with a hot air gun, or in the oven in the Prep room.
Discussion Questions
1. What develops the image?
2. What works as the fixer for the image?
3. Write balanced chemical equations for the reactions observed.
In: Chemistry
Just as pHpH is the negative logarithm of [H3O+][H3O+], pKapKa is the negative logarithm of KaKa
pKa=−logKapKa=−logKa
The Henderson-Hasselbalch equation is used to calculate the pHpH of buffer solutions:
pH=pKa+log[base][acid]pH=pKa+log[base][acid]
Notice that the pHpH of a buffer has a value close to the pKapKa of the acid, differing only by the logarithm of the concentration ratio [base]/[acid][base]/[acid]. The Henderson-Hasselbalch equation in terms of pOH and pKbpKb is similar.
pOH=pKb+log[acid][base]
How many grams of dry NH4ClNH4Cl need to be added to 1.80 LL of a 0.100 MM solution of ammonia, NH3NH3, to prepare a buffer solution that has a pHpH of 8.85? KbKb 1.8×10−51.8×10−5.
Express your answer with the appropriate units.
In: Chemistry
Calculate the theoretical yield of aspirin a) in moles and b) in grams. Assume use of 1.0 g salicylic acid and 2.5 mL acetic anhydride. Show all calculations.
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Which plastic types gives identical infrared spectra? Why does this make sense from their structures?
Background info: This is referring to the 6 plastic types: PETE, HDPE, LDPD. PVP, PP ad PS.
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A 1.0 L buffer solution is made up of 0.15M NaF and 0.20 M HF ( pK a = 3.17) . 0.05 mol of HCl is added to it. What is the new pH?
In: Chemistry
In: Chemistry
Please calculate the pH of each of the following solutions: 0.68 M NaCH3CO2 (aq); 0.45 M KCN (aq).
In: Chemistry
In: Chemistry
25 ml of 0.105 M HCl is titrated with 0.210 M NaOH
a. What is the ph after 5 ml of the base is added?
b. what is the ph at the equivalence point?
c. What is the ph after 15 ml of the base added?
d. how many ml of the base will be required to reach the end point?
In: Chemistry
In: Chemistry