Phenolphhalein indicator is used in this experiment because it changes color in the pH range of 8.0 to 9.6.

Show by calculation that phenolphthalein is an acceptable indicator for the titration of KHP with NaOH.

This is true if the pH at the equivalence point falls within this range.

In essence, what you need to do is to calculate the pH of the unprotonated phthalate salt. You may assume that the concentration of the salt is approximately 0.05 M at the equivalance point.

HINT: The salt is derived from the weak diprotic acid, which has Ka1 = 1.2 * 10^-3 and Ka2 = 3.9 * 10^-6

Which alcohol would react the fastest wit Lucas Reagent?: 1-pentanol, 2-pentanol, 3-pentanol or 2-methyl-2-butanol

A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0 mL of a pH = 10.18 solution.

Why does the negative potential superimposed with an AC current allow Low mass particles to pass through the quadrupole ? Explain in great detail with a figure or two.

Please don't copy and paste the old answer. I've already asked this question and the answer was incorrect

Calculate the pH for each of the following cases in the titration of 35.0 mL of 0.120 M KOH(aq), with 0.120 M HBr(aq).

(a) before addition of any HBr

(b) after addition of 13.5 mL of HBr

(c) after addition of 23.5 mL of HBr

(d) after the addition of 35.0 mL of HBr

(e) after the addition of 45.5 mL of HBr

(f) after the addition of 50.0 mL of HBr

1. What do you feel is the largest source of experimental error in your determination of R?

2. What would be the effect (increase, decrease, or no change) on the calculated value of R of each of the following experimental errors? a. The liquid level in the eudiometer tube is lower than that in the beaker, but this is not taken into consideration in the calculations.

b. The balance used to weigh the magnesium gives a mass that is higher than actual.

c. Some H2 escapes into the beaker during the reaction.

3. Most top-loading balances used in this experiment measure a mass only to the nearest mg ±0.001g. This significantly affects the calculation of R in this experiment. Explain why this is so. How might the procedure be modified to compensate for this systematic error?

What volume of a 15.0% by mass NaOH solution, which has a density of 1.116 g/mL, should be used to make 5.20 L of an NaOH solution with a pH of 10.0?
Express your answer to one significant figure and include the appropriate units.

Hi, i'm working on the lab report for Iodometric determination of Cu in Brass and i need help with these questions. I greatly appreciate your help.

Info: This experiment has two parts: standardization of the thiosulfate solution, and assay of the copper. In the standardization of the thiosulfate solution, a known amount of iodine is created from KIO3 and excess iodide, then titrated with the thiosulfate. In the copper assay, iodine is formed from the reaction between copper and excess iodide, then titrated with the thiosulfate.

1. How is the sample prepared for titration? how is the sample titrated?

2. what is the reaction between the titrant and iodine? how is the titrant concentration calculated?

Blood is a buffered solution with pH values ranging from 7.35-7.45. The important components of blood that contribute to its buffering capacity are species derived from carbonic acid and phosphoric acid. This problem emphasizes the phosphoric acid component.

(a) (3 pts) What are the three additional species in solution that can be derived from phosphoric acid using Brønsted-Lowry acid-base concepts? (I will refer to them as Species #1, #2, and #3 in the next parts.)

(b) (3 pts) Write the three equilibria that relate phosphoric acid with each of these species listed in part (a). (You should write three chemical equilibria, using chemical symbols, that all resemble the following.) “Phosphoric Acid” + ___________ “Species #” + ___________ (The items in blanks are needed to properly balance the equations.)

(c) (3 pts) For a pH value of 7.40, calculate the following ratios (you may use relevant Ka values that are tabulated for 25C in Appendix D of your textbook): [Species #1] [Species #2] [Species #3] ; ; [Phosphoric Acid] [Phosphoric Acid] [Phosphoric Acid]

(d) (2 pts) Which forms of phosphoric acid are the most abundant and the least abundant in water at a pH of 7.40?

(e) (10 pts) You work in a medical research lab with a biochemist who asks you to make a 1.00 L phosphate buffer stock solution with pH = 7.35. The total phosphorus concentration is to be 0.150 M. In the storeroom, there are the following reagents: (1) a 3.00 M phosphoric acid stock solution, (2) solid sodium dihydrogen phosphate, (3) solid sodium monohydrogen phosphate, (4) solid, sodium phosphate, (5) a 3.00 M HCl(aq) stock solution, (6) a 3.00 M NaOH(aq) stock solution, and (7) deionized water.

(i) (2 pts) To make an optimum buffer, it is important that the pKa of the acid part is close to the target pH of the buffer. Which phosphate species has a pKa value closest to pH = 7.35?

(ii) (4 pts) Choose this phosphate species (in i) as the only phosphorus component. What amounts of this substance and any other reagents (grams of solid(s); mL of any solution(s) and water) would you need to make the buffer with pH = 7.35?

(iii)(4 pts) Choose this phosphate species (in i) and either its conjugate acid or base as the only two phosphorus components. What amounts of this substance, its conjugate acid or base, and water (grams of solid(s); mL of any solution(s) and water) would you need to make the buffer with pH = 7.35?

For CO2+

1.Assuming that it has an octahedral geometric configuration, draw an orbital energy diagram and place the valence electrons in the diagram for its ground state.

2. For the same complex, draw an orbital energy diagram and place the valence electrons in the diagram that would indicate that it is in an excited state.

3. Using the two energy diagrams and the color you have chosen (as the color absorbed), describe the process by which transition metal complexes display color. Make sure you include delta Oct, the color that ould be observed and any other relavant information. The color chosen was RED

this procedure is a microscale hydration of norbornene.

1. What was the stereochemical outcome of the reaction? what evidence permitted a definitive assignment of stereochemistry?

2. Assemble a molecular model of norbornene and use it to explain why the obsvered product was obtained rather than the isomer.

3. The norbornyl carbocation does not rearrange to a tertiary carbocation even though there is a tertiary carbon adjacent to the secondary carbon bearing the positive charge. Suggest a possible explantion.

4.Norbornene is a strained alkene. It is very reactive toward hydration in aqueous acid. Explain how strain contributes to the high reactivity.

Consider the nonenzymatic elementary reaction A + B → C. When the concentrations of A and B are each 25.0 mM, the reaction velocity is measured as 4.11 µM C produced per minute.

Calculate the rate constant for this reaction with units!.

What is the molecularity of the above reaction?

If this reaction is in zero order kinetics how long would it take to produce 2.25 x 10^-3 moles of C from a starting concentration of reactants A and B of 100.0 mL of a 125 mM solution of each present?   Assume the rate constant determined above is the same rate constant at zero order kinetics, just units are changed on the rate constant to those for a zero order reaction.

If the reaction was in first order kinetics instead of zero order kinetics, how long would it take to produce 2.25 x 10^-3 moles of C from a starting concentration of 125 mM of each reactant and 100.0 mL volume? Assume the rate constant determined above in a, is the same rate constant at first order kinetics, just units are changed to reflect a first order rate constant.

What is the optimal temperature for lactase activity? Explain why enzymes are sensitive to temperature change

If Compound A (256 mg) was hydrolyzed using 12.5 mL of 1.0 M KOH and the amount of remaining KOH was back titrated and required 44.9 mL of 0.25 M HCL to neutralize the excess NaOH, what were the saponification equivalent and neutralization equivalent, and what is compound A?

1. Using the standard reduction potentials listed in Appendix E in the textbook, calculate the equilibrium constant for each of the following reactions at 298 K.

A. Fe(s)+Ni2+(aq)?Fe2+(aq)+Ni(s)

B.Co(s)+2H+(aq)?Co2+(aq)+H2(g)

C.10Br?(aq)+2MnO?4(aq)+16H+(aq)?2Mn2+(aq)+8H2O(l)+5Br2(l)

2. If the equilibrium constant for a two-electron redox reaction at 298 K is 1.8×10^?4, calculate the corresponding ?G? and E?cel under standard conditions.

2A. Express your answer using two significant figures. Delta G=kJ

2B. Express your answer using two significant figures. E cell= V