CHEM 110L - Experiment 5 Don't Get Stressed

Chemical eqbm STARTER: Driving Question The dichromate ion Cr,0,² and chromate ion Cro, exist in equilibrium, like this: Cr,0, (aq) + H,0 (1) = 2CrO,² (aq) + 2H' (aq) yellow orange a What would you see if you added dilute acid to a solution containing chromate ions? b How would you reverse the change?

What is the value in the concentration of the SCN Suppose the Keq for this experiment is 523. The initial concentration of the Fe+ is 4.00 x 10-2 M The initial concentration of the SCN is 1.00 x 10-3 M The reaction of the experiment: Fe3++ SCN 2 Fe(NCS)2+ The concentration of the SCN at equilibrium is : Y x 104M Your answer should have 2 sf

Which one of the following is the correct expression for the equilibrium constant for the reaction shown below? Ca2+(aq) + 2F–(aq)  ⇌  CaF2(s)   A.  K =  [Ca2+][F–]2   B.  K = [CaF2]  /  [Ca2+][F–]2   C.  K =  1 /  [Ca2+][F–]2   D.  K = 1 /  [Ca2+](2[F–])2   E.  None of the expressions

Equilibrium Constant Determination You will have to determine the equilibrium constant for the reaction between aqueous iron(III) ion and thiocyanate ion. The equilibrium equation is given below: Fe3+ (aq) + NCS– (aq) <---> FeNCS2+ (aq) yellow          colorless             red The absorbance of light is measured using a spectrophotometer. The higher the absorbance, the higher the concentration of FeNCS2+ present. At room temperature, 5.00ml of 0.200M iron(III)nitrate solution was mixed with 5.00ml of 0.200M potassium thiocyante solution. The absorbance of this mixture was 0.55. A 1cm thick cuvette was used. What is the path length (b) ? What is the molar extinction coefficient (E) ? What is the equilibrium concentration of iron(III)thiocyante of our solution? What are the equilibrium concentrations of Fe3+ and SCN- in our solution? Please help I am so confised!

Equilibrium: Co(H2O)62+ (aq) + 4 Cl-(aq) ⇌ CoCl42- (aq) + 6 H2O (l) pink blue a. You put 5 mL of stock solution into each of five test tubes. (25 mLs divided evenly into 5 test tubes). Test tube 1 was your control. To test tube 2, you added some water. Which direction did the equilibrium shift? How do you know? b. To test tube 3 you added some silver nitrate. Did this shift the equilibrium? If so, how is that possible as silver ion and nitrate ion are not in the equation? c. To test tube 5, you put the stock solution into hot water and it turned blue; then you put it into ice water and it turned pink. Explain what happened.

For the following acid/base reactions, draw the products and indicate the equilibrium position.

Calculate equilibrium constant for each solution and report to 3 significant figures. Calculate average equilibrium constant and report to 3 significant figures.

QUESTION 37 Based on the provided chart of reduction potentials, rank the following chemicals from strongest (1) to weakest (5) oxidizing agents. Half-Reaction End (V) +2.87 +1.51 +1.36 +1.33 +1.23 +1.06 +0.96 +0.80 +0.77 +0.68 +0.59 +0.54 +0.40 +0.34 0 [defined] -0.28 -0.44 -0.76 -0.83 -1.66 -2.71 -3.05 F2(8)+2e-2F (aq) MnO4 (aq) +8H(aq) +5e Mn²(aq) + 4H₂O(1) Cl₂(8)+2e-2 Cl(aq) Cr₂O72 (aq) +14 H(aq) + 6e2 Cr³(aq) + 7 H₂O(1) O₂(g) +4 H(aq) +4e-2H₂O(l) Brz(1)+2e-2 Br (aq) NO3(aq) + 4H(aq) + 3e NO(g) + 2H₂O(1) Ag (aq)+eAg(s) Fe³+ (aq) + e Fe²(aq) O₂(g) +2H(aq) +2e H₂O₂(aq) MnO4 (aq) + 2 H₂O(!)+3e MnO₂(s) + 4 OH(aq) 12(3)+2e-21 (aq) O₂(8)+2H₂O(1)+4e-4 OH(aq) Cu²(aq) +2e 2 H(aq)+2e Ni2(aq) +2e Fe (aq) +2e Cu(s) H-(8) Ni(s) Fe(s) Zn2(aq) +2e →→→ Zn(s) 2H₂O(1)+2e H₂(g) + 2OH(aq) Al(s) Al³(aq) + 3 e Na (aq)+eNa(s) Li' (aq) +eLi(s)

The concentration of glucose in an aqueous  solution can be determined by oxidation with ferricyanide ion, Fe(CN)63–.  The absorbance of the ferricyanide ion measured at 420 nm increases as the concentration of glucose increases. [Glucose], mg / mL Absorbance 0.005 0.132 0.010 0.290 0.020 0.498 0.030 0.642 0.040 0.750 Using the method of least-squares, give the equation of the best straight line through the points. Make sure that m=slope has 3 decimal places (XX.XXX) and y-intercept (b) has 2 significant figures (0.0XX). In your answer you should write in the form of y=mx+b. For instance, y = 12.316x + 0.072