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23 Nov 2019

Please explain how to do the following and providetheanswers...thanks

A student studied the clock reaction described inthisexperiment. She set up Reaction Mixture 2 by mixing 20 mL0.010M KI, 10 mL 0.001 M Na₂S₂O₃,10 mL0.040 M KBrO₃, and 10 mL 0.10 M HCL using theproceduregiven. It took about 45 seconds for the color toturn blue.

2. For Reaction Mixture 1 the student found that 85secondswere required. On dividing Equation 5 for ReactionMixture 1 byEquation 5 for Reaction Mixture 2, and after cancelingout thecommon terms (k', terms in (BrO₃^-)and (H+)),she got the following equation:

11.8 / 22 = (0.0020/0.0040)^m = (1/2)^m
Recognizing that 11.8/22 is about equal to 1/2, she obtainedanapproximate value for m. What was that value?

m=

By taking logarithms of both sides of the equation, she gotanexact value for m. What was that value?

m=

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Help with this chem pre lab assignment please!! Any help isappreciated! show steps if possible!

A student studied the clock reaction described in thisexperiment. She set up Reaction Mixture 2 by mixing 20 mL 0.010 MKI, 10 mL .001 M Na2S2O3, 10 mL .040 M KBrO3, and 10 mL 0.10 M HClusing the procedure given. It took 45 seconds for the color to turnto blue.

a. She found the concentration of each reactant in the reactingmixture by realizing that the number of moles of each reactant didnot change when that reactant was mixed with the others, but thatits concentration did. For any reactant A,

no. moles A = MA Stock X VStock= M A Mixture X V Mixture

The volume of the mixture was 50 mL. Revising the above equation,she obtained

M A Mixture= M A stock X (VStock (mL)) / 50 mL

Find the concentrations of each reactant by using the aboveequation.
(I-)__________ M; (BrO3-) _____________M; (H+) ____________M

b. what is the relative rate of the reaction (1000/t)?_________________

c. Knowing the relative rate of the reaction for mixture 2 and theconcentrations of I-, BrO3-, and H+ in that mixture, she was ableto set up equation 5 for the relative rate of the reaction, Theonly quantities that remained unknown were k,m,n, and p. Set upEquation 5 as she did, presuming she did it properly.

2. For reaction Mixture 1 the student found that 85 seconds wererequired. On dividing Equation 5 for Reaction Mixture 1 by Equation5 for Reaction Mixture 2, and after canceling out the common terms(k, terms in (BrO3-) and (H+)), she got the followingequation,

11.8/22=(0.0020/.0040)^m= (1/2)^m

Recongnizing that 11.8/22 is about equal to 1/2, she obtained anapproximate value for m. What is that value?

m=_________________

By taking logarithms of both sides of the equation, she got anexact value for m. What was that value?

m=_________________

The kinetics of the reaction below were studied. The volumes of 0.040 M KBrO3, 0.040 M KI,

0.00050 M Na2S2O3, 0.040 M KCl, H2O and a buffer solution employed in each trial are shown

in the table below. One drop of 1% aqueous starch solution was also added in each trial. The

buffer solution was a pH = 4.74 solution containing 0.50 M acetic acid and 0.50 M sodium acetate; Ka = 1.8 x 10â5 for acetic acid. Each trial was performed at 25â¦C. For each trial, the reaction mixture was initially colorless after combining all solutions; appearance of a blue solution color in the reaction mixture signaled that all of the thiosulfate ion initially present had reacted and marked the end of the timing period. The initial reaction rate for each trial was calculated from the change in molar concentration of thiosulfate ion from each trial; the equation for calculating Initial Rate is shown below, where Ît is the elapsed time between combining all solutions and appearance of the blue solution color. Each solution volume was measured to the nearest 0.1 mL. (ie 5 mL shown in the table is 5.0 mL.)

BrO3- (aq) + 6Iâ(aq) + 6H+(aq) â 3H2O(l) + Brâ(aq) + 3I2(aq)

Initial rate = - 13âS2O32-ât

Volume (mL) Used

Trial #	KBrO3	KI	Na2S2O3	KCl	H2O	Buffer	Initial Rate (M/s)
1	10	10	5	0	0	15	5.0 x 10â6
2	5	10	5	5	0	15	2.5 x 10â6
3	10	5	5	5	0	15	2.5 x 10â6
4	10	10	2.5	0	2.5	15	5.0 x 10â6

a)Which pair of trials could be used to determine the order for Iâ? Justify your choice.

b)How would you determine the order for H+? Be as specific as possible.

c)What would be the value for the initial rate if 5 mL KBrO3 solution, 5 mL KI solution, 5 mL Na2S2O3 solution, 10 mL KCl solution, 15 mL pH = 4.74 buffer solution, and 1 drop of 1% starch solution were used?

d)Why do Trials 1 and 4 have the same initial rate?

e)What time was required for the color change to occur in Trial 1?

f)What was the purpose of adding 5 mL of 0.040 M KCl in Trial 2?

g)How would you experimentally verify that KCl does not cause the color change from colorless to blue? Be as specific as possible.

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