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Solve for x and list step by step.Kc = 7

Solve for x and list step by step.Kc = 7-example-1
User Shatia
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1 Answer

18 votes
18 votes

ANSWER


x\text{ = }\frac{-1.45\text{ - 0.847i}}{12}\text{ or }\frac{-1.45\text{ + 0.847i}}{12}

Explanation

The equation of a chemical equilibrium reaction is given below as


Kc\text{ = }(0.04-0.4x+x^2)/(0.0225+0.15x+x^2)

Recall that, Kc = 7

The next step is to substitute the value of Kc = 7 into the above equation


7\text{ = }(0.04-0.4x+x^2)/(0.0225+0.15x+x^2)

The next step is to cross multiply


\begin{gathered} 0.04-0.4x+x^2\text{ = }7\cdot(0.0225+0.15x+x^2) \\ \text{open the parentheses} \\ 0.04-0.4x+x^2\text{ = }7\cdot\text{ }0.0225\text{ + 7 }\cdot\text{ 0.15x + 7 }\cdot x^2 \\ 0.04-0.4x+x^2\text{ = }0.1575+1.05x+7x^2 \\ \text{Collect the like terms} \\ x^2-7x^2\text{ - 0.4x - 1.05x + 0.04 - 0.1575 = 0} \\ -6x^2\text{ -1.45x - }0.1175\text{ = 0} \\ \end{gathered}

The next step is to solve for x in the equation using the general quadratic formula

Recall that,


ax^2\text{ + bx + c = 0}

Relating the two equations together, then, we have the following

a = -6

b = -1.45

c = -0.1175


\begin{gathered} x\text{ = }\frac{-b\text{ }\pm\sqrt[]{b^2\text{ - 4ac}}}{2a} \\ x\text{ = }\frac{-(-1.45)\text{ }\pm\sqrt[]{-1.45^2\text{ - (4 }\cdot-\text{ 6 }\cdot\text{ -0.1175)}}}{2\cdot\text{ -6}} \\ x\text{ = }\frac{1.45\text{ }\pm\sqrt[]{2.1025\text{ - }(2.82)}}{-12} \\ x\text{ = }\frac{\text{ 1.45 }\pm\sqrt[]{-0.7175}}{-12} \\ x\text{ = }\frac{1.45\pm\sqrt[]{0.7175}\text{ }\sqrt[]{-1}}{-12} \\ \text{ recall that, }\sqrt[]{-1\text{ }}\text{ = i} \\ x\text{ = }\frac{1.45\pm\sqrt[]{0.7175}\text{ i}}{-12} \\ x\text{ = }\frac{1.45\text{ }\pm0.847i}{-12} \\ x\text{ = }\frac{1.45\text{ + 0.847i}}{-12}\text{ or }\frac{1.45-\text{ 0.847i}}{-12} \\ x\text{ = }\frac{-1.45\text{ - 0.847i}}{12}\text{ or }\frac{-1.45\text{ + 0.847i}}{12} \end{gathered}

User RRikesh
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