Arangetram cost breakdown

Explain your observation upon addition of 12 M HCl(aq) to the original CoCl2 solution. Include a balanced net ionic equation and explain which way the equilibrium shifts as more HCl(aq) is added and why in terms of LeChâtelier’s principle.

b.) Account for your observation when adding water to the [CoCl4]2- complex solution. Explain which way the equilibrium in (a) shifts as water is added and why in terms of LeChâtelier’s principle.

Part II: Equilibria Involving Sparingly Soluble Salts

Appearance of Na2CO3 Solution:

Clear, no color

Appearance of AgNO3 Solution:

Clear no color

Observed Changes on Mixing:

bright yellow “lemon-aid” color, with a cloudy precip.

a.) Write the balanced net ionic equation for the equilibrium that is established upon mixing. Why does this equilibrium occur?

Observations upon addition of HNO3:

1 drop cleared the solution, no color, no precipitate

a.) Account for your observations when adding HNO3(aq). Include the balanced net ionic equation and explain which way the equilibrium in (a) shifts and why in terms of Le Châtelier’s principle.

b.) Which ions remain in the test tube after addition of HNO3(aq)?

Observations upon addition of HCl:

Formed a solid and chunky precipitate, though not cloudy

a.) Write the balanced net ionic equation for the equilibrium that is established when HCl(aq) is added to the test tube. Why does this equilibrium occur?

Observations upon addition of NH3:

Solution clears out, removing the cloudy precipitate

a.) Explain your observation when excess NH3(aq) is added to the test tube. Include a balanced net ionic equation and explain which way the equilibrium in (d) shifts as NH3 (aq) is added and why in terms of LeChâtelier’s principle.

Observations upon addition of HNO3:

Remains clear, and colorless, produces a water vapor and heat.

a.) Account for your observations when adding HNO3(aq). Include a balanced net ionic equation for the reaction that occurs and explain which way the equilibrium in (e) shifts as HNO3(aq) is added and why in terms of Le Châtelier’s principle.

b.) Which ions and/or solids are present in the test tube after the addition of HNO3(aq)?

Observations upon 2nd addition of NH3:

No change was observed

a.) Explain your observation when excess NH3(aq) is added to the test tube. Include a balanced net ionic equation and explain which way the equilibrium in (d) shifts as NH3 (aq) is added and why in terms of LeChâtelier’s principle.

Observations upon addition of KI:

Color changes to bright yellow “lemonade” color, with a cloudy precipitate

a.) Account for your observations when adding KI(aq). Include a balanced net ionic equation for the reaction that occurs and explain which way the equilibrium in (h) shifts as KI(aq) is added and why in terms of Le Châtelier’s principle.

Part III: Effect of Temperature on Equilibria

Temperature of cool CoCl2:

24° C

Color of cool CoCl2 (before heating):

Clear and medium red

Temperature of hot [CoCl4]2-:

75° C

Color of hot [CoCl4]2- (after heating):

Deep dark red, though still clear

a.) Is the reaction exothermic or endothermic? Explain your answer.

Discussion Questions

1. Based on your observations on Part I, what could be expected to happen if the solution of [Cu(NH3)4]2+ were diluted with water. Use a balanced net ionic equation to explain.

2. In the equilibrium, X3+(aq){yellow}+Y-(aq){colorless}↔[XY4]-(aq){red}, what would be indicated if heating the solution caused an intense dark red color and the solution turned yellow in an ice bath?

3. Consider the following equilibria occurring simultaneously:

Fe3+(aq){pale yellow}+SCN-(aq){colorless}↔[FeNCS]2+(aq){dark red}

Ag+(aq)+SCN-(aq)↔AgSCN(s)

2Fe3+(aq)+Sn2+(aq)↔ 2Fe2+(aq)+Sn4+(aq)