Chemistry, 29.02.2020 02:52 eriksprincess13

An aqueous solution was prepared at 21 oC by mixing 7.00 mL 2.00 x 10-2mol L-1Fe3+, 2.00 mL 1.50 x 10-3 mol L-1SCN−, and 1.00 mL water. At equilibrium, the concentration of the product complex, [Fe(SCN)2+]eq was determined to be 1.74 x 10-4mol L-1. What is the value of the equilibrium constant K for the reaction of interest at 21 oC?

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Answer from: bry7474

The value of equilibrium constant for the given reaction is 99.85

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$ .....(1)

For $Fe^{3+}$ ions:

Molarity of $Fe^{3+}$ solution = $2.00\times 10^{-2}M$

Volume of solution = 7.00 mL = 0.007 L (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

$2.00\times 10^{-2}M=\frac{\text{Moles of }Fe^{3+}\text{ ions}}{0.007L}\\\\\text{Moles of }Fe^{3+}\text{ ions}=(2.00\times 10^{-2}mol/L\times 0.007L)=1.4\times 10^{-4}mol$

For $SCN^{-}$ ions:

Molarity of $SCN^{-}$ solution = $1.50\times 10^{-3}M$

Volume of solution = 2.00 mL = 0.002 L

Putting values in equation 1, we get:

$1.50\times 10^{-3}M=\frac{\text{Moles of }SCN^{-}\text{ ions}}{0.002L}\\\\\text{Moles of }SCN^-\text{ ions}=(1.50\times 10^{-3}mol/L\times 0.002L)=3\times 10^{-6}mol$

Volume of the container = [7 + 2 + 1] = 10 mL = 0.010 L

$\text{Molarity of }Fe^{3+}\text{ ions}=\frac{1.4\times 10^{-4}mol}{0.01}=1.4\times 10^{-2}M$

$\text{Molarity of }SCN^{-}\text{ ions}=\frac{3.0\times 10^{-6}mol}{0.01}=3.0\times 10^{-4}M$

The chemical equation for the formation of $[FeSCN^{2+}]$ complex follows:

$Fe^{2+}+SCN^-\rightleftharpoons [FeSCN^{2+}]$

Initial: 0.014 $3.0\times 10^{-4}$

At eqllm: 0.014-x $3.0\times 10^{-4}-x$ x

We are given:

Equilibrium concentration of $[FeSCN^{2+}]=1.74\times 10^{-4}M=x$

Equilibrium concentration of $[Fe^{2+}]\text{ ions}=(1.4\times 10^{-2}-x)=(1.4-0.0174)\times 10^{-3}=1.383\times 10^{-2}M$

Equilibrium concentration of $[SCN^{-}]\text{ ions}=(3.0\times 10^{-4}-x)=(3.0-1.74)\times 10^{-4}=1.26\times 10^{-4}M$

The expression of $K_{eq}$ for above equation follows:

$K_{eq}=\frac{[FeSCN^{2+}]}{[Fe^{3+}][SCN^-]}$

Putting values in above equation, we get:

$K_{eq}=\frac{(1.74\times 10^{-4})}{(1.383\times 10^{-2})\times (1.26\times 10^{-4})}\\\\K_{eq}=99.85$

Hence, the value of equilibrium constant for the given reaction is 99.85

Answer from: Quest

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

Write 15 uses of a mercury barometer along with its characterestics

Answer from: Quest

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).

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An aqueous solution was prepared at 21 oC by mixing 7.00 mL 2.00 x 10-2mol L-1Fe3+, 2.00 mL 1.50 x 1...

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