Magnus Ehingers undervisning

Allt du behöver för A i Biologi, Kemi, Bioteknik, Gymnasiearbete m.m.

Kemi 2

Administration

Kapitel 2

kapitel 5Kompletta lösningar (med videor) till utvalda övningsuppgifter i kapitel 2 i Ehinger: Kemi 2 (NA förlag).

Hoppa direkt till uppgift: 2.12, 2.16, 2.22

2.12

\(K= \frac {[\text{NO}]^2}{[\text{N}_2][\text{O}_2]}\)

\(1,4 \cdot 10^{-4} = \frac {x^2}{0,036\text{M} \cdot 0,0089\text{M}}\)

\(0,036\text{M} \cdot 0,0089\text{M} \cdot 1,4 \cdot 10^{-4} = x^2\)

\(x = \sqrt{0,036\text{M} \cdot 0,0089\text{M} \cdot 1,4 \cdot 10^{-4}} = 2,117924 \cdot 10^{-4}\text{M} \approx 2,1 \cdot 10^{-4}\text{M}\)

2.16

a.

\(Q = \frac {[\text{H}_2][\text{I}_2]}{[\text{HI}]^2} = \frac {1,00 \cdot 1,00}{1,00^2} = 1 > K = 1,36 \cdot 10^{-3}\)

Eftersom \(Q > K\) kommer reaktionen att gå åt vänster.

b.

  [HI] [H2] [I2]  
f.r. 1,00 1,00 1,00 M
\(+2x\) \(-x\) \(-x\) M
v.j. \(1,00+2x\) \(1,00-x\) \(1,00-x\) M

 

\(K = \frac {[\text{H}_2][\text{I}_2]}{[\text{HI}]^2}\)

\(1,36 \cdot 10^{-3} = \frac {(1,00-x)(1,00-x)}{(1,00+2x)^2} = \frac {(1,00-x)^2}{(1,00+2x)^2}\)

\(\sqrt{1,36 \cdot 10^{-3}} = \frac {1,00-x}{1,00+2x}\)

\(x = 0,896965\)

\([\text{HI}] = (1,00-2x)\text{M} = (1,00 - 2 \cdot 0,896965)\text{M} = 2,79393\text{M} \approx 2,79\text{M}\)

\([\text{H}_2] = [\text{I}_2] = (1,00 - x)\text{M} = (1,00 - 0,896965)\text{M} = 0,103035\text{M} \approx 0,103\text{M}\)

2.22

[Video kommer inom kort.]

a.

O2(g) + N2(g) ⇌ 2NO(g)

\(Q = \frac {[\text{NO}]^2}{[\text{O}_2][\text{N}_2]} = \frac {(0,22\text{M})^2}{1,0\text{M} \cdot 1,0\text{M}} = 0,0484 < K = 0,097\)

Reaktionen kommer att gå åt höger.

  [O2] [N2] [NO]  
f.r. \[1,0\] \[1,0\] \[0,22\] M
\[-x\] \[-x\] \[+2x\] M
v.j. \[1,0-x\] \[1,0-x\] \[0,22+2x\] M


\(K = \frac {[\text{NO}]^2}{[\text{O}_2][\text{N}_2]}\)

\(0,097 = \frac {(0,22 + 2x)^2}{(1,0-x)(1,0-x)} = \frac {(0,22 + 2x)^2}{(1,0-x)^2}\)

\(\sqrt{0,097} = \sqrt{\frac {(0,22 + 2x)^2}{(1,0-x)^2}} = \frac {0,22 + 2x}{1,0-x}\)

\(\sqrt{0,097} \cdot (1,0-x) = 0,22 + 2x\)

\(\sqrt{0,097} - \sqrt{0,097} \cdot x = 0,22 + 2x\)

\(\sqrt{0,097} - 0,22 = 2x + \sqrt{0,097} \cdot x = x(2 + \sqrt{0,097})\)

\(x = \frac {\sqrt{0,097} - 0,22}{2 + \sqrt{0,097}} = 0,03956317\)

\([\text{O}_2] = [\text{N}_2] = (1,0 - x)\text{M} = (1,0 - 0,03956317)\text{M} = 0,96043683\text{M} \approx 0,96\text{M}\)

\([\text{NO}] = (0,22 + 2x)\text{M} = (0,22 + 2 \cdot 0,03956317)\text{M} = 0,29912635\text{M} \approx 0,30\text{M}\)

 

 

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