You considered the equilibrium: Fe3+(aq) + SCN-(aq) Fe(SCN)2+(aq), and compared the color of the solutions in four test tubes. In the third test tube, you added 6 M NaOH dropwise. How do you explain the formation of a precipitate and the shift in equilibrium in terms of LeChatelier's Principle? a. The addition of NaOH produced the precipitate, Fe(OH)3, which removed Fe3+ from the system. To reduce the stress of the removal of Fe3+ and to re-establish equilibrium, the system shifted to the left increasing [Fe3+] and decreasing the [Fe(SCN)2+]. Increasing the [Fe3+] produced a yellow colored solution. b. The addition of NaOH produced the precipitate, NaSCN, which removed SCN- from the system. To reduce the stress of the removal of SCN- and to re-establish equilibrium, the system shifted to the left increasing [SCN-] and decreasing the [Fe(SCN)2+]. Increasing the [SCN-] produced a yellow colored solution. c. The addition of NaOH produced the precipitate, Fe(SCN)(OH)2, which removed Fe(SCN)2+ from the system. The removal of Fe(SCN)2+ from the system caused the deep red color to disappear leaving only the yellow color.

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.

consider the reaction below.

 no rx

at 500 k, the reaction is at equilibrium with the following concentrations.

[pci5]= 0.0095 m

[pci3] = 0.020

[ci2] = 0.020 m

what is the equilibrium constant for the given reaction?

0.042

0.42

2.4

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