Kafli 15 - Svör við æfingum

Svör við æfingum

15.1 Útfelling og upplausn

(a)
${\begin{aligned} {\text{AgI}(s)⇌} & {{{\text{Ag}}}^{\text{+}}(aq)+} & {{\text{I}}^{\text{−}}(aq)} \\ & x & {x_} \end{aligned}}$
(b)
${\begin{aligned} {{{\text{CaCO}}}_{3}(s)⇌} & {{{\text{Ca}}}^{\text{2+}}(aq)+} & {{{\text{CO}}}_{3}^{\text{2−}}(aq)} \\ & {x_} & x \end{aligned}}$
(c)
${\begin{aligned} \end{aligned}}$
(d)
${\begin{aligned} {{{\text{Mg}}}_{3}{{({{\text{PO}}4})}}2(s)⇌} & {{{\text{3Mg}}}^{\text{2+}}(aq)+} & {{{\text{2PO}}}_{4}^{\text{3−}}(aq)} \\ & {{x}_} & {\frac{2}{3}x} \end{aligned}}$
(e)
${\begin{aligned} {{{\text{Ca}}}_{5}({{\text{PO}}}_{4}{{)}}_{3}\text{OH}(s)⇌} & {{{\text{5Ca}}}^{\text{2+}}(aq)+} & {{{\text{3PO}}}_{4}^{\text{3−}}(aq)+} & {{{\text{OH}}}^{\text{−}}(aq)} \\ & {{5x}_} & {{3x}_} & x \end{aligned}}$

Engin breyting verður. Fast efni hefur virknina 1, hvort sem það er lítið eða mikið af því.

Leysni silfurbrómíðs við nýja hitastigið verður að vera þekkt. Venjulega eykst leysnin og eitthvað af fasta silfurbrómíðinu leysist upp.

CaF₂, MnCO₃ og ZnS

(a) ${{{\text{LaF}}}_{3}(s)⇌{{\text{La}}}^{\text{3+}}(aq)+{{\text{3F}}}^{\text{−}}(aq)\, {K}_{{\text{sp}}}=[{{\text{La}}}^{\text{3+}}]{{[\text{F}}}^{\text{−}}{]}^{3};}$
(b) ${{{\text{CaCO}}}_{3}(s)⇌{{\text{Ca}}}^{\text{2+}}(aq)+{{\text{CO}}}_{3}^{\text{2−}}(aq)\, {K}_{{\text{sp}}}=[{{\text{Ca}}}^{\text{2+}}][{{\text{CO}}}_{3}^{\text{2−}}];}$
(c) ${{{\text{Ag}}}_{2}{{\text{SO}}}_{4}(s)⇌{{\text{2Ag}}}^{\text{+}}(aq)+{{\text{SO}}}_{4}^{\text{2−}}(aq)\, {K}_{{\text{sp}}}={[{\text{Ag}}\text{+}]}2[{{\text{SO}}}_{4}^{\text{2−}}];}$
(d) ${{{\text{Pb(OH)}}}_{2}(s)⇌{{\text{Pb}}}^{\text{2+}}(aq)+{{\text{2OH}}}^{\text{−}}(aq)\, {K}_{{\text{sp}}}=[{{\text{Pb}}}^{\text{2+}}]{[{\text{OH}}\text{−}]}2}$

(a) 1,77 $\times$ 10^–7; (b) 1,6 $\times$ 10^–6; (c) 2,2 $\times$ 10^–9; (d) 7,91 $\times$ 10^–22

(a) 2 $\times$ 10^–2 M; (b) 1,5 $\times$ 10^–3 M; (c) 2,27 $\times$ 10^–9 M; (d) 2,2 $\times$ 10^–10 M

(a) 6,4 $\times$ 10⁻⁹ M = [Ag⁺], [Cl⁻] = 0,025 M. Athugun: ${\frac{{6,4\, \times \, {{10}}^{{-9}}\, M}}{{0,025\, M}}\, \times \, \text{100%}=\text{2,6}\, \times \, {{10}}^{{-5}}%,}$ óveruleg breyting;
(b) 2,2 $\times$ 10⁻⁵ M = [Ca²⁺], [F⁻] = 0,0013 M. Athugun: ${\frac{{\text{2,26}\, \times \, {{10}}^{{-5}}\, M}}{{0,00133\, M}}\, \times \, \text{100%}=\text{1,70%}.}$ Þetta gildi er minna en 5% og má hunsa það.
(c) 0,2238 M = ${[{{\text{SO}}}_{4}^{{2\text{−}}}];}$ [Ag⁺] = 7,4 $\times$ 10^–3 M. Athugun: ${\frac{{3,7\, \times \, {{10}}^{{-3}}}}{{0,2238}}\, \times \, 100%=\text{1,64}\, \times \, {{10}}^{{-2}};}$ skilyrðið er uppfyllt.
(d) [OH^–] = 2,8 $\times$ 10^–3 M; 5,7 $\times$ 10⁻¹² M = [Zn²⁺]. Athugun: ${\frac{{5,7\, \times \, {{10}}^{{-12}}}}{{2,8\, \times \, {{10}}^{{-3}}}}\, \times \, \text{100%}=\text{2,0}\, \times \, {{10}}^{{-7}}%;}$ x er minna en 5% af [OH^–] og er því óverulegt.

(a) Ekki má hunsa breytingu á upphafsstyrk sameiginlegrar jónar (verður að leysa annars stigs jöfnu)
[Ti⁺] = 0,031 M
[Cl^–] = 0,0056 M (b) Má hunsa breytingu á upphafsstyrk sameiginlegrar jónar.
[Ba²⁺] = 2,4 $\times$ 10^–4 M
[F^–] = 0,313 M;
(c) Má hunsa breytingu á upphafsstyrk sameiginlegrar jónar.
[Mg²⁺] = 0,0244 M
${[{\text{C}}_{2}{\text{O}}_{4}^{{\text{2−}}}]=2,9\, \times \, {{10}}^{{\text{−5}}}\, M}$
(d) Má hunsa breytingu á upphafsstyrk sameiginlegrar jónar.
[Ca²⁺] = 5,18 $\times$ 10^–4 M
[C₂)₄^2–] = 0,051 M

Breytingarnar á styrk eru meiri en 5% og fara því yfir hámarksgildið til að hunsa breytinguna.

CaSO₄∙2H₂O er auðleystasta Ca-saltið í mól/L og það er einnig auðleystasta Ca-saltið í g/L.

7,8 $\times$ 10^–3 M = ${[{{\text{SO}}}_{4}^{\text{2−}}]}$ = [Ca²⁺]; Þar sem þessi styrkur er hærri en 2,60 $\times$ 10^–3 M, uppfyllir „gipsvatn“ ekki staðlana.

Massi (CaSO₄·2H₂O) = 0,72 g

(a) [Ag⁺] = [I^–] = 1,3 $\times$ 10^–5 M; (b) [Ag⁺] = 2,88 $\times$ 10^–2 M, ${[{{\text{SO}}}_{4}^{{\text{2−}}}]}$ = 1,44 $\times$ 10^–2 M; (c) [Mn²⁺] = 3,7 $\times$ 10^–5 M, [OH^–] = 7,4 $\times$ 10^–5 M; (d) [Sr²⁺] = 4,3 $\times$ 10^–2 M, [OH^–] = 8,6 $\times$ 10^–2 M; (e) [Mg²⁺] = 1,3 $\times$ 10^–4 M, [OH^–] = 2,6 $\times$ 10^–4 M.

(a) 1,45 $\times$ 10^–4; (b) 8,2 $\times$ 10^–55; (c) 1,35 $\times$ 10^–4; (d) 1,18 $\times$ 10^–5; (e) 1,08 $\times$ 10^–10

(a) CaCO₃ fellur út. (b) Efnasambandið fellur ekki út. (c) Efnasambandið fellur ekki út. (d) Efnasambandið fellur út.

1,42 $\times$ 10⁻⁹ M

9,2 $\times$ 10⁻¹³ M

[Ag⁺] = 1,8 $\times$ 10^–3 M

6,3 $\times$ 10^–4

(a) 2,25 L; (b) 7,2 $\times$ 10^–7 g

100% af því er uppleyst

(a) ${{{\text{Hg}}}_{2}^{{\text{2+}}}}$ og Cu²⁺: Bætið við ${{{\text{SO}}}_{4}^{\text{2−}}.}$ (b) ${{{\text{SO}}}_{4}^{{\text{2−}}}}$ og Cl^–: Bætið við Ba²⁺. (c) Hg²⁺ og Co²⁺: Bætið við S^2–. (d) Zn²⁺ og Sr²⁺: Bætið við OH^– þar til [OH^–] = 0,050 M. (e) Ba²⁺ og Mg²⁺: Bætið við ${{{\text{SO}}}_{4}^{\text{2−}}.}$ (f) ${{{\text{CO}}}_{3}^{{\text{2−}}}}$ og OH^–: Bætið við Ba²⁺.

AgI fellur fyrst út.

1,5 $\times$ 10⁻¹² M

3,99 kg

(a) 3,1 $\times$ 10^–11; (b) [Cu²⁺] = 2,6 $\times$ 10^–3; ${[{{\text{IO}}}_{3}^{\text{−}}]}$ = 5,3 $\times$ 10^–3

9,3 $\times$ 10^–6 g Pb(OH)₂

${{{\text{Mg(OH)}}}_{2}(s)⇌{{\text{Mg}}}^{\text{2+}}+{{\text{2OH}}}^{\text{−}}\, {K}_{{\text{sp}}}=[{{\text{Mg}}}^{\text{2+}}]{[{\text{OH}}\text{−}]}2}$
1,23 $\times$ 10⁻³ g Mg(OH)₂

MnCO₃ mun myndast fyrst þar sem það hefur lægsta K_sp gildið meðal þessara samsvarandi efnasambanda og er því minnst leysanlegt. MgCO₃•3H₂O fellur út síðast þar sem það hefur hæsta K_sp gildið og er mest leysanlegt. K_sp gildi.

15.2 Lewis-sýrur og -basar

þegar magn fasta efnisins er svo lítið að ekki myndast mettuð lausn

8,2 $\times$ 10^–5 M

5 $\times$ 10²³

[Cd²⁺] = 5,0 $\times$ 10^–5 M; [CN^–] = 2,0 $\times$ 10^–4 M

This table has two main columns and three rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ) and Equilibrium ( M ). The second column has the header, “[ C d ( C N ) subscript 4 to the second power superscript negative sign ] [ C N superscript negative sign ] [ C d to the second power superscript positive sign ].” Under the second column is a subgroup of two rows and three columns. The first column contains the following: 0.250 and 0.250 minus x. The second column contains the following: 0 and 4 x. The third column contains the following: 0 and x.

[Co³⁺] = 3,0 $\times$ 10^–6 M; [NH₃] = 1,8 $\times$ 10^–5 M

1,3 g

0,79 g

(a)

(b)

(c)

(d)

(e)

This figure shows a chemical reaction modeled with structural formulas. On the left side is a structure with a central C atom. O atoms, each with two unshared electron pairs, are double bonded to the left and right sides of the C atom. Following a plus sign is another structure in brackets which has an O atom with three unshared electron dot pairs single bonded to an H atom on the right. Outside the brackets is superscript negative sign. Following a right pointing arrow is a structure in brackets that has a central C atom to which 3 O atoms are bonded. Above and slightly to the right, one of the O atoms is connected with a double bond. This O atom has two unshared electron pairs. The second O atom is single bonded below and slightly to the right. This O atom has three unshared electron pairs. The third O atom is bonded to the left of the C atom. This O atom has two unshared electron pairs and an H atom single bonded to its left. Outside the brackets to the right is a superscript negative symbol.

This figure shows a chemical reaction modeled with structural formulas. On the left side is a structure that has a central B atom to which 3 O atoms are bonded. The O atoms above and below slightly right of the B atom each have an H atom single bonded to the right. The third O atom is single bonded to the left side of the B atom. This O atom has an H atom single bonded to its left side. All O atoms in this structure have two unshared electron pairs. Following a plus sign is another structure which has an O atom single bonded to an H atom on its right. The O atom has three unshared electron pairs. The structure appears in brackets with a superscript negative sign. Following a right pointing arrow is a structure in brackets has a central B atom to which 4 O atoms are bonded. The O atoms above, below, and right of the B atom each hav an H atom single bonded to the right. The third O atom is single bonded to the left side of the B atom. This O atom has an H atom single bonded to its left side. All O atoms in this structure have two unshared electron pairs. Outside the brackets to the right is a superscript negative symbol.

This figure illustrates a chemical reaction using structural formulas. On the left, two I atoms, each with 3 unshared electron pairs, are joined with a single bond. Following a plus sign is another structure which has an I atom with four pairs of electron dots and a superscript negative sign. Following a right pointing arrow is a structure in brackets that has three I atoms connected in a line with single bonds. The two end I atoms have three unshared electron dot pairs and the I atom at the center has two unshared electron pairs. Outside the brackets is a superscript negative sign.

This figure illustrates a chemical reaction using structural formulas. On the left, an A l atom is positioned at the center of a structure and three Cl atoms are single bonded above, left, and below. Each C l atom has three pairs of electron dots. Following a plus sign is another structure which has an F atom is surrounded by four electron dot pairs and a superscript negative symbol. Following a right pointing arrow is a structure in brackets that has a central A l atom to which 4 C l atoms are connected with single bonds above, below, to the left, and to the right. Each C l atom in this structure has three pairs of electron dots. Outside the brackets is a superscript negative symbol.

This figure illustrates a chemical reaction using structural formulas. On the left is a structure which has an S atom at the center. O atoms are single bonded above and below. These O atoms have three electron dot pairs each. To the right of the S atom is a double bonded O atom which has two pairs of electron dots. Following a plus sign is an O atom which is surrounded by four electron dot pairs and has a superscript 2 negative. Following a right pointing arrow is a structure in brackets that has a central S atom to which 4 O atoms are connected with single bonds above, below, to the left, and to the right. Each of the O atoms has three pairs of electron dots. Outside the brackets is a superscript 2 negative.

(a)

(b) ${{\text{H}}_{3}{\text{O}}^{+}+{{\text{CH}}}_{3}^{\text{−}}\, \longrightarrow \, {{\text{CH}}}_{4}+{\text{H}}_{2}\text{O}}$

(c) ${\text{CaO}+{{\text{SO}}}_{3}\, \longrightarrow \, \text{CaSO}4}$

(d) ${{{\text{NH}}}_{4}^{+}+{\text{C}}_{2}{\text{H}}_{5}{\text{O}}^{\text{−}}\, \longrightarrow \, {\text{C}}_{2}{\text{H}}_{5}\text{OH}+{{\text{NH}}}_{3}}$

This figure represents a chemical reaction in two rows. The top row shows the reaction using chemical formulas. The second row uses structural formulas to represent the reaction. The first row contains the equation H C l ( g ) plus P H subscript 3 ( g ) right pointing arrow left bracket P H subscript 4 right bracket superscript plus plus left bracket C l with 4 pairs of electron dots right bracket superscript negative sign. The second row begins on the left with H left bracket C l with four unshared electron pairs right bracket plus a structure in brackets with a central P atom with H atoms single bonded at the left, above, and to the right. A single unshared electron pair is on the central P atom. Outside the brackets to the right is a superscript plus sign. Following a right pointing arrow is a structure in brackets with a central P atom with H atoms single bonded at the left, above, below, and to the right. Outside the brackets is a superscript plus sign. This structure is followed by a plus and a C l atom in brackets with four unshared electron pairs and a superscript negative sign.

This figure represents a chemical reaction using structural formulas. A structure is shown in brackets on the left which is composed of a central O atom with one unshared electron pair and three single bonded H atoms to the left, right, and above the atom. Outside the brackets to the right is a superscript plus sign. Following a plus sign, is another structure in brackets composed of a central C atom with one unshared electron pair and three single bonded H atoms to the left, right, and above the atom. Outside the brackets to the right is a superscript negative sign. Following a right pointing arrow is a structure with a central C atom with H atoms single bonded above, below, left and right. Following a plus sign is a structure with a central O atom with two unshared electron pairs and two H atoms connected with single bonds.

This figure represents a chemical reaction using structural formulas. On the left, C a superscript 2 plus is just left of bracket O with four unshared electron pairs right bracket superscript 2 negative plus a structure with a central S atom to which two O atoms are single bonded at the left and right, and a single O atom is double bonded above. The two single bonded O atoms each have three unshared electron pairs and the double bonded O atom has two unshared electron pairs. Following a right pointing arrow is C a superscript 2 plus just left of a structure in brackets with a central S atom which has 4 O atoms single bonded at the left, above, below, and to the right. Each of the O atoms has three unshared electron pairs. Outside the brackets to the right is a superscript two negative.

This figure represents a chemical reaction using structural formulas. A structure is shown in brackets on the left which is composed of a central N atom with four single bonded H atoms to the left, right, above, and below the atom. Outside the brackets to the right is a superscript plus sign. Following a plus sign, is another structure in brackets composed of a C atom with three single bonded H atoms above, below, and to the left. A second C atom is single bonded to the right. This C atom has H atoms single bonded above and below. To the right of the second C atom, an O atom is single bonded. This O atom has three unshared electron pairs. Outside the brackets to the right is a subperscript negative. Following a right pointing arrow is a structure composed of a C atom with three single bonded H atoms above, below, and to the left. A second C atom is single bonded to the right. This C atom has H atoms single bonded above and below. To the right of the second C atom, an O atom is single bonded. This O atom has two unshared electron pairs and an H atom single bonded to its right.

0,0281 g

${{{\text{HNO}}}_{3}(l)+\text{HF}(l)\, \longrightarrow \, {\text{H}}_{2}{{\text{NO}}}_{3}^{+}+{\text{F}}^{\text{−}};}$ ${\text{HF}(l)+{{\text{BF}}}_{3}(g)\, \longrightarrow \, {\text{H}}^{+}+{{\text{BF}}}_{4}}$

(a) ${{\text{H}}_{3}{{\text{BO}}}_{3}+{\text{H}}_{2}\text{O}\, \longrightarrow \, {\text{H}}_{4}{{\text{BO}}}_{4}^{\text{−}}+{\text{H}}^{+};}$ (b) Rafeindabygging og sameindalögun eru eins — hvort tveggja ferflötungur. (c) Ferflötungslögunin er í samræmi við sp³ blendingsgerð.

15.3 Tengd jafnvægi

0,014 M

7,2 $\times$ 10^–15 M

4,4 $\times$ 10⁻²² M

[OH⁻] = 4,5 $\times$ 10⁻⁶; [Al³⁺] = 2 $\times$ 10^–16 (mólarleysni)

${{\text{K}}_{sp}=[{\text{Ba}}^{2+}][{\text{SO}}_{4}^{{\text{2−}}}]=[{\text{Ba}}^{2+}](0,049)=1,08\times {10}^{–10}[{\text{Ba}}^{2+}]=2,2\times {10}^{–9}}$ ; (mólarleysni)

[OH⁻] = 7,6 $\times$ 10⁻³ M; [Pb²⁺] = 2,1 $\times$ 10^–11 (mólarleysni)

7,66

(a) K_sp = [Mg²⁺][F^–]² = (1,21 $\times$ 10^–3)(2 $\times$ 1,21 $\times$ 10^–3)² = 7,09 $\times$ 10^–9
(b) 7,09 $\times$ 10^–7 M
(c) Ákvarðið styrk Mg²⁺ og F^– sem verður til staðar í lokarúmmálinu. Berið saman gildi jónamargfeldisins [Mg²⁺][F^–]² við K_sp. Ef þetta gildi er stærra en K_sp mun útfelling eiga sér stað.
0,1000 L $\times$ 3,00 $\times$ 10^–3 M Mg(NO₃)₂ = 0,3000 L $\times$ M Mg(NO₃)₂
M Mg(NO₃)₂ = 1,00 $\times$ 10^–3 M
0,2000 L $\times$ 2,00 $\times$ 10^–3 M NaF = 0,3000 L $\times$ M NaF
M NaF = 1,33 $\times$ 10^–3 M
jónamargfeldi = (1,00 $\times$ 10^–3)(1,33 $\times$ 10^–3)² = 1,77 $\times$ 10^–9 Þetta gildi er minna en K_sp, þannig að engin útfelling mun eiga sér stað.
(d) MgF₂ er minna leysanlegt við 27 °C en við 18 °C. Þar sem viðbættur varmi virkar eins og viðbætt hvarfefni, þegar hann birtist á myndefnahliðinni, segir lögmál Le Châteliers að jafnvægið muni færast yfir á hvarfefnahliðina til að vinna gegn álaginu. Afleiðingin er sú að minna af efninu leysist upp. Þetta ástand er til staðar í okkar tilfelli. Þess vegna er efnahvarfið útvermið.

BaF₂, Ca₃(PO₄)₂, ZnS; hvert þeirra er salt af veikri sýru og ${[{\text{H}}_{3}{\text{O}}^{+}]}$ úr perklórsýru dregur úr jafnvægisstyrk anjónarinnar og eykur þar með styrk katjónanna

Áhrif á magn fasts CaHPO₄, [Ca²⁺], [OH^–]: (a) eykst, eykst, minnkar; (b) minnkar, eykst, minnkar; (c) engin áhrif, engin áhrif, engin áhrif; (d) minnkar, eykst, minnkar; (e) eykst, engin áhrif, engin áhrif