Equilibrium and le chatelier lab answers

Exercise 1

CHEM 182 DL1 Equilibrium and Le Châtelier’s Principle

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T he Reaction is Endothermic because the substance became more acidic which equals to higher heat energy.

1. Use your results to determine if the forward reaction in the potassium chromate/HCl reaction endothermic or exothermic. Explain your answer, using the table below to help construct your thoughts.

K=(Cr2 O7)(H20)(KCl)2 / (K2 CrO4) (HCL)2

2. Write the equation for the equilibrium constant (K) of the reaction studied in this exercise.

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Data Table 1: Chromate and Dichromate

Q=1.6 * 10 (-10 exponent)

Use this information to answer Questions 3, 4, and 5:

The equilibrium constant (K) of the reaction below is K = 6.0 x 10 , with initial concentrations as follows:

[H ] = 1.0 x 10 M, [N ] = 4.0 M, and [NH ] = 1.0 x 10 M.

3. Consider the chemical reaction: N + 3H yields 2NH . If the concentration of the reactant H was increased f rom 1.0 x 10 M to 2.5 x 10 M, calculate the reaction quotient (Q) and determine which way the chemical system would shif t by comparing the value of Q to K.

-2

2 -2 2 3 -4

2 2 3 2 -2 -1

Q=1.270131585632272 * 10 (2 exponent) It will shif t lef t.

4. If the concentration of the reactant H was decreased f rom 1.0 x 10 M to 2.7 x 10 M, calculate the reaction quotient (Q) and determine which way the chemical system would shif t by comparing the value of Q to K.

2 -2 -4

Q=7.84 * 10(-4 exponent). It will shif t right.

5. If the concentration of the product NH was increased f rom 1.0 x 10 M to 5.6 x 10 M, calculate the reaction quotient (Q) and determine which way the chemical system would shif t by comparing the value of Q to K.

3 -4 -3

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Data Table 2: Endothermic & Exothermic Equilibrium Position

Color of Chromate Color of Dichromate

Color of Chromate Number of Drops of NaOH to Shift Equilibrium Position

Dark yellow Orange

Dark yellow 7

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Exercise 2

Reaction at Room Temperature

Color

Chemical System Shift (Left or Right)

Explanation of why chemical system is shifted to the left or to the right

Reaction in Cold Water Bath

Color

Chemical System Shift (Left or Right)

Explanation of why chemical system is shifted to the left or to the right

Reaction in Hot Water Bath

Color

Chemical System Shift (Left or Right)

Explanation of why chemical system is shifted to the left or to the right

Red Orange

Bright Orange

Left- towards the reactants

There were solid particles on the bottom of the pipet while the liquid maintained the majority of the pipet. So there was a solid potion and liquid potion. potion.

Red-Orange

Right-Towards the products

The solution was all liquid, so there were no solid particles. This means the reactants mixed together formed the product.

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Data Table 3: Ferric Ferrocyanide

The equilibrium position would shift left because the product ratio increases when NaOH is added.

1. From your observations and data collected in Data Table 3, describe the direction of the equilibrium posit ion shif t upon addit ion of NaOH.

Color of Potassium Ferrocyanide Color of Ferric Ferrocyanide

Color of Potassium Ferrocyanide

Number of Drops of NaOH to Shift Equilibrium Position

Color of Potassium Ferrocyanide

Observations when Equilibrium is Shifted

Light yellow Dark blue/greenish

Light yellow 4 drops

Light yellow The dark blue/greenish substance turned brown while the surrounding substance turned yellow.