3.E: Muundo wa Vitu na Ufumbuzi (Mazoezi)

3.1: Mfumo wa Mfumo na Dhana ya Mole

Je, ni jumla ya molekuli (amu) ya kaboni katika kila moja ya molekuli zifuatazo?

1. (a) CH ₄
2. (b) ChCl ₃
3. (c) C ₁₂ H ₁₀ O ₆
4. (d) CH ₃ CH _{2 CH 2} CH ₂ CH ₂ CH ₃

(a) 12.01 amu; (b) 12.01 amu; (c) 144.12 amu; (d) 60.05 amu

Je, ni molekuli ya jumla ya hidrojeni katika kila molekuli?

1. (a) CH ₄
2. (b) ChCl ₃
3. (c) C ₁₂ H ₁₀ O ₆
4. (d) CH ₃ CH _{2 CH 2} CH ₂ CH ₂ CH ₃

Tumia molekuli ya molekuli au formula ya kila yafuatayo:

(a) P ₄

(b) H ₂ O

(c) Ca (NO ₃) ₂

(d) CH ₃ CO ₂ H (asidi asetiki)

(e) C ₁₂ H ₂₂ O ₁₁ (sucrose, miwa).

(a) 123.896 amu; (b) 18.015 amu; (c) 164.086 amu; (d) 60.052 amu; (e) 342.297 amu

Kuamua molekuli ya Masi ya misombo ifuatayo:

(a)

(b)

(c)

(d)

Kuamua molekuli ya Masi ya misombo ifuatayo:

(a)

(b)

(c)

(d)

1. (a) 56.107 amu;
2. (b) 54.091 amu;
3. (c) 199.9976am;
4. (d) 97.9950 amu

Ambayo molekuli ina molekuli ya Masi ya 28.05 amu?

(a)

(b)

(c)

Andika sentensi inayoelezea jinsi ya kuamua idadi ya moles ya kiwanja katika molekuli inayojulikana ya kiwanja ikiwa tunajua formula yake ya Masi.

Tumia formula ya Masi ili kupata molekuli ya molar; ili kupata idadi ya moles, ugawanye wingi wa kiwanja na molekuli ya molar ya kiwanja kilichoonyeshwa kwa gramu.

Linganisha mole 1 ya H ₂, 1 mole ya O ₂, na 1 mole ya F ₂.

1. (a) Ambayo ina idadi kubwa ya molekuli? Eleza kwa nini.
2. (b) Ambayo ina molekuli kubwa zaidi? Eleza kwa nini.

Ambayo ina wingi mkubwa wa oksijeni: 0.75 mol ya ethanol (C ₂ H ₅ OH), 0.60 mol ya asidi ya fomu (HCO ₂ H), au 1.0 mol ya maji (H ₂ O)? Eleza kwa nini.

Asidi ya fomu. Fomu yake ina atomi mara mbili za oksijeni nyingi kama misombo nyingine mbili (moja kila mmoja). Kwa hiyo, 0.60 mol ya asidi ya fomu itakuwa sawa na 1.20 mol ya kiwanja kilicho na atomi moja ya oksijeni.

Ambayo ina idadi kubwa ya atomi za oksijeni: 1 mol ya ethanol (C ₂ H ₅ OH), 1 mol ya asidi ya fomu (HCO ₂ H), au 1 mol ya maji (H ₂ O)? Eleza kwa nini.

Je, molekuli ya Masi na molekuli ya molar ya kiwanja ni sawa na ni tofauti gani?

Rasi mbili zina thamani sawa ya namba, lakini vitengo ni tofauti: Masi ya masi ni masi ya molekuli 1 ilhali molekuli ya molar ni masi ya molekuli 6.022 × 10 ²³.

Tumia molekuli ya molar ya kila misombo ifuatayo:

1. (a) fluoride ya hidrojeni, HF
2. (b) amonia, NH ₃
3. (c) asidi ya nitriki, HNO ₃
4. (d) sulfate ya fedha, Ag ₂ SO ₄
5. (e) asidi ya boroni, B (OH) ₃

Tumia molekuli ya molar ya kila yafuatayo:

1. (a) S ₈
2. (b) C ₅ H ₁₂
3. (c) Sc ₂ (SO ₄) ₃
4. (d) CH ₃ COCH ₃ (asetoni)
5. (e) C ₆ H ₁₂ O ₆ (glucose)

(a) 256.528 g/mol; (b) 72.150 g mol ^-1; (c) 378.103 g mol ^-1; (d) 58.080 g mol ^-1; (e) 180.158 g ^{mol -1}

Tumia molekuli ya empirical au molekuli ya molekuli na molekuli ya molar ya kila madini yafuatayo:

1. (a) chokaa, CaCO ₃
2. (b) halite, NaCl
3. (c) beryl, Kuwa ₃ Al ₂ Si ₆ O ₁₈
4. (d) malachite, Cu ₂ (OH) ₂ CO ₃
5. (e) turquoise, Cual ₆ (PO _{4) 4} (OH) ₈ (H ₂ O ₄)

Tumia molekuli ya molar ya kila yafuatayo:

1. (a) halothane ya anesthetic, C ₂ HbrClF ₃
2. (b) paraquat ya madawa ya kulevya, C ₁₂ H ₁₄ N ₂ Cl ₂
3. (c) caffeine, C ₈ H ₁₀ N ₄ O ₂
4. (d) urea, CO (NH ₂) ₂
5. (e) sabuni ya kawaida, C ₁₇ H ₃₅ CO ₂ Na

(a) 197.382 g mol ^-1; (b) 257.163 g mol ^-1; (c) 194.193 g mol ^-1; (d) 60.056 g mol ^-1; (e) 306.464 g ^{mol -1}

Kuamua idadi ya moles ya kiwanja na idadi ya moles ya kila aina ya atomi katika kila moja ya yafuatayo:

1. (a) 25.0 g ya propylene, C ₃ H ₆
2. (b) 3.06 × 10 ^{-3 g} ya glycine ya amino asidi, C ₂ H ₅ NO ₂
3. (c) 25 lb ya Treflan ya dawa, C ₁₃ H ₁₆ N ₂ O ₄ F (1 lb = 454 g)
4. (d) 0.125 kg ya wadudu Paris Green, Cu ₄ (ASO ₃) ₂ (CH ₃ CO ₂) ₂
5. (e) 325 mg ya aspirini, C ₆ H ₄ (CO ₂ H) (CO ₂ CH ₃)

Kuamua wingi wa kila moja ya yafuatayo:

1. (a) 0.0146 mol KOH
2. (b) 10.2 mol ethane, C ₂ H ₆
3. (c) 1.6 × ^{10 -3} mol Na ₂ ASA ₄
4. (d) 6.854 × 10 ³ mol glucose, C ₆ H ₁₂ O ₆
5. (e) 2.86 mol Co (NH ₃) ₆ Cl ₃

1. (a) 0.819 g;
2. (b) 307 g;
3. (c) 0.23 g;
4. (d) 1.235 × 10 ⁶ g (1235 kg);
5. (e) 765 g

Kuamua idadi ya moles ya kiwanja na kuamua idadi ya moles ya kila aina ya atomi katika kila moja ya yafuatayo:

1. (a) 2.12 g ya bromidi ya potasiamu, KBR
2. (b) 0.1488 g ya asidi fosforasi, H ₃ PO ₄
3. (c) 23 kg ya calcium carbonate, CaCO ₃
4. (d) 78.452 g ya sulfate ya alumini, Al ₂ (SO ₄) ₃
5. (e) 0.1250 mg ya caffeine, C ₈ H ₁₀ N ₄ O ₂

Kuamua wingi wa kila moja ya yafuatayo:

1. (a) 2.345 ml LiCl
2. (b) 0.0872 mol asetilini, C ₂ H ₂
3. (c) 3.3 × ^{10 -2} mol Na ₂ CO ₃
4. (d) 1.23 × 10 ³ mol fructose, C ₆ H ₁₂ O ₆
5. (e) 0.5758 mol _FeSO (H ₂ O) ₇

1. (a) 99.41 g;
2. (b) 2.27 g;
3. (c) 3.5 g;
4. (d) kilo 222;
5. (e) 160.1 g

Mahitaji ya chini ya kila siku ya chakula ya leucine ya amino asidi, C ₆ H ₁₃ NO ₂, ni 1.1 g Mahitaji haya ni nini katika moles?

Kuamua wingi kwa gramu ya kila yafuatayo:

1. (a) 0.600 mol ya atomi za oksijeni
2. (b) 0.600 mol ya molekuli ya oksijeni, O ₂
3. (c) 0.600 mol ya molekuli ya ozoni, O ₃

(a) 9.60 g; (b) 19.2 g; (c) 28.8 g

Mwanamke mwenye kilo 55 ana 7.5 × 10 ^1-3 mol ya hemoglobin (molekuli ya molar = 64,456 g/mol) katika damu yake. Ni molekuli ngapi za hemoglobin hii? Je! Ni kiasi gani kwa gramu?

Kuamua idadi ya atomi na wingi wa zirconium, silicon, na oksijeni kupatikana katika 0.3384 mol ya zircon, ZrSiO ₄, jiwe semiprecious.

zirconium: 2.038 × 10 ²³ atomi; 30.87 g; silicon: 2.038 × 10 ²³ atomi; 9.504 g; oksijeni: 8.151 × 10 ²³ atomi; 21.66 g

Kuamua ni ipi kati ya yafuatayo ina molekuli kubwa ya hidrojeni: 1 mol ya CH ₄, _0.6 mol ya C _{6 H 6}, au 0.4 mol ya C ₃ H ₈.

Kuamua ni ipi kati ya yafuatayo ina molekuli kubwa ya alumini: 122 g ya Alpo ₄, 266 g ya Al ₂ Cl ₆, au 225 g ya Al ₂ S ₃.

Lapo ₄: 1.000 ml

All ₂ Cl ₆: 1.994 mol

All ₂ S ₃: 3.00 moll

Diamond ni aina moja ya kaboni ya msingi. Pete ya ushiriki ina almasi yenye uzito wa 1.25 karati (1 carat = 200 mg). Ni atomi ngapi zilizopo katika almasi?

Almasi ya Cullinan ilikuwa almasi kubwa ya asili iliyowahi kupatikana (25 Januari 1905). Ilikuwa na uzito wa karati 3104 (1 karati = 200 mg). Ni atomi ngapi za kaboni zilizopo jiwe?

3.113 × 10 ²⁵ C atomi

Moja ya gramu 55 ya huduma ya nafaka fulani hutoa 270 mg ya sodiamu, 11% ya posho ya kila siku iliyopendekezwa. Ni moles ngapi na atomi za sodiamu ziko katika posho ya kila siku iliyopendekezwa?

Nafaka fulani ya mbegu ya mbegu ina gramu 11.0 za sukari (sucrose, C ₁₂ H ₂₂ O ₁₁) kwa ukubwa wa gramu 60.0. Ni huduma ngapi za nafaka hii zinapaswa kuliwa kula kula 0.0278 moles ya sukari?

0.865 servings, au kuhusu 1 kuwahudumia.

Bomba la dawa ya meno lina 0.76 g ya monofluorophosphate ya sodiamu (Na ₂ PO ₃ F) katika 100 ml.

1. Ni umati gani wa atomi za fluorini katika mg ulikuwepo?
2. Ni atomi ngapi za fluorini zilizopo?

Ni ipi kati ya yafuatayo inawakilisha idadi ndogo ya molekuli?

1. 20.0 g ya H ₂ O (18.02 g/mol)
2. 77.0 g ya CH ₄ (16.06 g/mol)
3. 68.0 g ya kHH ₂ (42.09 g/mol)
4. 100.0 g ya N ₂ O (44.02 g/mol)
5. 84.0 g ya HF (20.01 g/mol)

20.0 g H ₂ O inawakilisha idadi ndogo ya molekuli kwani ina idadi ndogo ya moles.

3.2: Kuamua Fomu za Masi na za Masi

Ni habari gani tunahitaji kuamua formula ya Masi ya kiwanja kutoka kwa formula ya empirical?

Tumia zifuatazo kwa takwimu nne muhimu:

1. (a) muundo wa asilimia ya amonia, NH ₃
2. (b) asilimia muundo wa picha “hypo,” Na ₂ S ₂ the ₃
3. (c) asilimia ya ioni ya kalsiamu katika Ca ₃ (PO ₄) ₂

(a)% N = 82.24%

% H = 17.76%;

(b)% Na = 29.08%

% S = 40.56%

% O = 30.36%;

(c)% Ca ²⁺ = 38.76%

Kuamua zifuatazo kwa takwimu nne muhimu:

1. muundo wa asilimia ya asidi hydrazoic, HN ₃
2. muundo wa asilimia ya TNT, C ₆ H ₂ (CH ₃) (NO ₂) ₃
3. asilimia ya SO ₄ ^2— katika Al ₂ (SO ₄) ₃

Kuamua asilimia amonia, NH ₃, katika Co (NH ₃) ₆ Cl ₃, kwa takwimu tatu muhimu.

% NH ₃ = 38.2%

Kuamua asilimia maji katika _{CuSO 4} 5H ₂ O kwa takwimu tatu muhimu.

Kuamua formula empirical kwa misombo na nyimbo zifuatazo asilimia:

(a) 15.8% kaboni na 84.2% sulfuri

(b) 40.0% kaboni, 6.7% hidrojeni, na 53.3% oksijeni

(a) CS ₂

(b) CH ₂ O

Kuamua formula empirical kwa misombo na nyimbo zifuatazo asilimia:

(a) 43.6% fosforasi na 56.4% oksijeni

(b) 28.7% K, 1.5% H, 22.8% P, na 47.0% The

Kiwanja cha kaboni na hidrojeni kina 92.3% C na kina molekuli ya molar ya 78.1 g/mol. Nini formula yake ya Masi?

C ₆ H ₆

Dichloroethane, kiwanja ambacho hutumiwa mara nyingi kwa kusafisha kavu, kina kaboni, hidrojeni, na klorini. Ina molekuli ya molar ya 99 g/mol. Uchambuzi wa sampuli unaonyesha kuwa ina 24.3% kaboni na 4.1% hidrojeni. Nini formula yake ya Masi?

Kuamua formula empirical na Masi kwa asbestosi chrysotile. Chrysotile ina muundo wa asilimia zifuatazo: 28.03% Mg, 21.60% Si, 1.16% H, na 49.21% O. molekuli ya molar kwa chrysotile ni 520.8 g/mol.

Mg ₃ Si ₂ H ₃ O ₈ (formula empirical), Mg ₆ Si ₄ H ₆ O ₁₆ (molekuli formula)

Polima ni molekuli kubwa linajumuisha vitengo rahisi vinavyorudiwa mara nyingi. Kwa hiyo, mara nyingi huwa na kanuni rahisi za upimaji. Tumia kanuni za maandishi ya polima zifuatazo:

1. Lucite (Plexiglas); 59.9% C, 8.06% H, 32.0% O
2. Saran; 24.8% C, 2.0% H, 73.1% Cl
3. polyethilini; 86% C, 14% H
4. polystyrene; 92.3% C, 7.7% H
5. Orlon; 67.9% C, 5.70% H, 26.4% N

Mtengenezaji mkuu wa nguo ya nguo alianzisha rangi mpya ya njano. Rangi ina muundo wa asilimia 75.95% C, 17.72% N, na 6.33% H kwa wingi na molekuli ya molar ya karibu 240 g/mol. Kuamua formula ya Masi ya rangi.

C ₁₅ H ₁₅ N ₃

3.3: Molarity

Maswali

Eleza mabadiliko gani na kile kinachokaa sawa wakati 1.00 L ya suluhisho la NaCl hupunguzwa hadi 1.80 L.

Ni habari gani tunahitaji kuhesabu molarity ya suluhisho la asidi sulfuriki?

Tunahitaji kujua idadi ya moles ya asidi sulfuriki kufutwa katika suluhisho na kiasi cha suluhisho.

Ina maana gani tunaposema kwamba sampuli 200-ml na sampuli 400-ml ya suluhisho la chumvi ina molarity sawa? Kwa njia gani sampuli mbili zinafanana? Kwa njia gani sampuli hizi mbili zinatofautiana?

Kuamua molarity kwa kila moja ya ufumbuzi wafuatayo:

1. 0.444 ml ya CoCl ₂ katika 0.654 L ya suluhisho
2. 98.0 g ya asidi ya fosforasi, H ₃ PO ₄, katika 1.00 L ya suluhisho
3. 0.2074 g ya hidroksidi kalsiamu, Ca (OH) ₂, katika 40.00 ml ya suluhisho
4. 10.5 kg ya Na ₂ SO ₄ · 10H ₂ O katika 18.60 L ya suluhisho
5. 7.0 × 10 ^-3 mol ya I ₂ katika 100.0 ml ya suluhisho
6. 1.8 × 10 ⁴ mg ya HCl katika 0.075 L ya suluhisho

1. (a) 0.679 M;
2. (b) 1.00 M;
3. (c) 0.06998 M;
4. (d) 1.75 M;
5. (e) 0.070 M;
6. (f) 6.6 M

Kuamua molarity ya kila moja ya ufumbuzi wafuatayo:

1. 1.457 mol kCl katika 1.500 L ya suluhisho
2. 0.515 g ya H ₂ SO ₄ katika 1.00 L ya suluhisho
3. 20.54 g ya Al (NO ₃) ₃ katika 1575 ml ya suluhisho
4. 2.76 kg ya _{CuSO 4} · 5H ₂ O katika 1.45 L ya suluhisho
5. 0.005653 mol ya Br ₂ katika 10.00 ml ya suluhisho
6. 0.000889 g ya glycine, C ₂ H ₅ NO ₂, katika 1.05 ml ya suluhisho

Majibu:

a) 0.9713 M

b.) 5.25x10 ^-3 M

c.) 6.122x10 ^-2 M

d.) 7.62 M

e.) 0.5653 M

f.) 1.13x10 ^-2 M

Fikiria swali hili: Je, ni wingi wa solute katika 0.500 L ya 0.30 M glucose, C ₆ H ₁₂ O ₆, kutumika kwa sindano ya ndani?

(a) Eleza hatua zinazohitajika ili kujibu swali.

(b) Jibu swali.

(a) kuamua idadi ya moles ya glucose katika 0.500 L ya suluhisho; kuamua molekuli molar ya glucose; kuamua wingi wa glucose kutoka kwa idadi ya moles na molekuli yake ya molar; (b) 27 g

Fikiria swali hili: Je, ni wingi wa solute katika 200.0 L ya ufumbuzi wa 1.556- M wa KBR?

1. (a) Eleza hatua zinazohitajika ili kujibu swali.
2. (b) Jibu swali.

Jibu:

(a)

1. Tumia kwa moles ya KBr kwa kuzidisha Molarity kwa kiasi cha suluhisho (200.0 L)
2. Kupata Misa Molar ya KBr na kubadilisha moles ya solute kwa gramu

(b)

\(\dfrac{1.556\:moles\:\ce{KBr}}{1\:\cancel{L}}\times 200.0\:\cancel{L}=311.2\:moles\:\ce{KBr}\)

\(311.2\:\cancel{moles}\:\ce{KBr}\times\dfrac{119.0\:g\:\ce{KBr}}{1\:\cancel{mole}\:\ce{KBr}}=37,030\:g\)

37,030g; 37.03 kg

Calculate the number of moles and the mass of the solute in each of the following solutions:

1. (a) 2.00 L of 18.5 M H₂SO₄, concentrated sulfuric acid
2. (b) 100.0 mL of 3.8 × 10⁻⁵ M NaCN, the minimum lethal concentration of sodium cyanide in blood serum
3. (c) 5.50 L of 13.3 M H₂CO, the formaldehyde used to “fix” tissue samples
4. (d) 325 mL of 1.8 × 10⁻⁶ M FeSO₄, the minimum concentration of iron sulfate detectable by taste in drinking water

(a) 37.0 mol H₂SO₄;

3.63 × 10³ g H₂SO₄;

(b) 3.8 × 10⁻⁶ mol NaCN;

1.9 × 10⁻⁴ g NaCN;

(c) 73.2 mol H₂CO;

2.20 kg H₂CO;

(d) 5.9 × 10⁻⁷ mol FeSO₄;

8.9 × 10⁻⁵ g FeSO₄

Calculate the number of moles and the mass of the solute in each of the following solutions:

1. 325 mL of 8.23 × 10⁻⁵ M KI, a source of iodine in the diet
2. 75.0 mL of 2.2 × 10⁻⁵ M H₂SO₄, a sample of acid rain
3. 0.2500 L of 0.1135 M K₂CrO₄, an analytical reagent used in iron assays
4. 10.5 L of 3.716 M (NH₄)₂SO₄, a liquid fertilizer

Answers:

a. 2.67x10^-5 moles KI; 4.44x10^-3g KI

b. 1.7x10^-6 moles H₂SO₄ ; 1.6x10^-4 g H₂SO₄

c. 2.838x10^-2 moles K₂CrO₄ ; 5.510g K₂CrO₄

d. 39.0 moles (NH₄)₂SO₄ ; 5,160 g (NH₄)₂SO₄

Consider this question: What is the molarity of KMnO₄ in a solution of 0.0908 g of KMnO₄ in 0.500 L of solution?

1. (a) Outline the steps necessary to answer the question.
2. (b) Answer the question.

(a) Determine the molar mass of KMnO₄; determine the number of moles of KMnO₄ in the solution; from the number of moles and the volume of solution, determine the molarity; (b) 1.15 × 10⁻³ M

Consider this question: What is the molarity of HCl if 35.23 mL of a solution of HCl contain 0.3366 g of HCl?

1. (a) Outline the steps necessary to answer the question.
2. (b) Answer the question.

Answer:

(a)

1. Convert g of HCl to moles of HCl and convert mL of solution to L of solution
2. Divide moles of HCl by L of solution

(b)

\(0.3366\:\cancel{g}\:\ce{HCl}\times\dfrac{1\:mole\:\ce{HCl}}{36.46\:\cancel{g}\:\ce{HCl}}=9.232\times10^{-3}\:moles\:\ce{HCl}\)

\(35.23\:mL = 0.03523\:L\)

\(\dfrac{9.232\times10^{-3}\:moles\:\ce{HCl}}{0.03523\:L}=0.2621\:M\:\ce{HCl}\)

0.2621 M ;

Calculate the molarity of each of the following solutions:

(a) 0.195 g of cholesterol, C₂₇H₄₆O, in 0.100 L of serum, the average concentration of cholesterol in human serum

(b) 4.25 g of NH₃ in 0.500 L of solution, the concentration of NH₃ in household ammonia

(c) 1.49 kg of isopropyl alcohol, C₃H₇OH, in 2.50 L of solution, the concentration of isopropyl alcohol in rubbing alcohol

(d) 0.029 g of I₂ in 0.100 L of solution, the solubility of I₂ in water at 20 °C

(a) 5.04 × 10⁻³ M;

(b) 0.499 M;

(c) 9.92 M;

(d) 1.1 × 10⁻³ M

Calculate the molarity of each of the following solutions:

1. 293 g HCl in 666 mL of solution, a concentrated HCl solution
2. 2.026 g FeCl₃ in 0.1250 L of a solution used as an unknown in general chemistry laboratories
3. 0.001 mg Cd²⁺ in 0.100 L, the maximum permissible concentration of cadmium in drinking water
4. 0.0079 g C₇H₅SNO₃ in one ounce (29.6 mL), the concentration of saccharin in a diet soft drink.

There is about 1.0 g of calcium, as Ca²⁺, in 1.0 L of milk. What is the molarity of Ca²⁺ in milk?

0.025 M

What volume of a 1.00-M Fe(NO₃)₃ solution can be diluted to prepare 1.00 L of a solution with a concentration of 0.250 M?

If 0.1718 L of a 0.3556-M C₃H₇OH solution is diluted to a concentration of 0.1222 M, what is the volume of the resulting solution?

0.5000 L

If 4.12 L of a 0.850 M-H₃PO₄ solution is be diluted to a volume of 10.00 L, what is the concentration the resulting solution?

What volume of a 0.33-M C₁₂H₂₂O₁₁ solution can be diluted to prepare 25 mL of a solution with a concentration of 0.025 M?

1.9 mL

What is the concentration of the NaCl solution that results when 0.150 L of a 0.556-M solution is allowed to evaporate until the volume is reduced to 0.105 L?

What is the molarity of the diluted solution when each of the following solutions is diluted to the given final volume?

1. (a) 1.00 L of a 0.250-M solution of Fe(NO₃)₃ is diluted to a final volume of 2.00 L
2. (b) 0.5000 L of a 0.1222-M solution of C₃H₇OH is diluted to a final volume of 1.250 L
3. (c) 2.35 L of a 0.350-M solution of H₃PO₄ is diluted to a final volume of 4.00 L
4. (d) 22.50 mL of a 0.025-M solution of C₁₂H₂₂O₁₁ is diluted to 100.0 mL

1. (a) 0.125 M;
2. (b) 0.04888 M;
3. (c) 0.206 M;
4. (e) 0.0056 M

What is the final concentration of the solution produced when 225.5 mL of a 0.09988-M solution of Na₂CO₃ is allowed to evaporate until the solution volume is reduced to 45.00 mL?

A 2.00-L bottle of a solution of concentrated HCl was purchased for the general chemistry laboratory. The solution contained 868.8 g of HCl. What is the molarity of the solution?

11.9 M

An experiment in a general chemistry laboratory calls for a 2.00-M solution of HCl. How many mL of 11.9 M HCl would be required to make 250 mL of 2.00 M HCl?

What volume of a 0.20-M K₂SO₄ solution contains 57 g of K₂SO₄?

1.6 L

The US Environmental Protection Agency (EPA) places limits on the quantities of toxic substances that may be discharged into the sewer system. Limits have been established for a variety of substances, including hexavalent chromium, which is limited to 0.50 mg/L. If an industry is discharging hexavalent chromium as potassium dichromate (K₂Cr₂O₇), what is the maximum permissible molarity of that substance?

3.4: Other Units for Solution Concentrations

Questions

1. Consider this question: What mass of a concentrated solution of nitric acid (68.0% HNO3 by mass) is needed to prepare 400.0 g of a 10.0% solution of HNO3 by mass?
   1. Outline the steps necessary to answer the question.
   2. Answer the question.
2. What mass of a 4.00% NaOH solution by mass contains 15.0 g of NaOH?
3. What mass of solid NaOH (97.0% NaOH by mass) is required to prepare 1.00 L of a 10.0% solution of NaOH by mass? The density of the 10.0% solution is 1.109 g/mL.
4. What mass of HCl is contained in 45.0 mL of an aqueous HCl solution that has a density of 1.19 g cm–3 and contains 37.21% HCl by mass?
5. The hardness of water (hardness count) is usually expressed in parts per million (by mass) of \(\ce{CaCO_3}\), which is equivalent to milligrams of \(\ce{CaCO_3}\) per liter of water. What is the molar concentration of Ca²⁺ ions in a water sample with a hardness count of 175 mg CaCO₃/L?
6. The level of mercury in a stream was suspected to be above the minimum considered safe (1 part per billion by weight). An analysis indicated that the concentration was 0.68 parts per billion. Assume a density of 1.0 g/mL and calculate the molarity of mercury in the stream.
7. In Canada and the United Kingdom, devices that measure blood glucose levels provide a reading in millimoles per liter. If a measurement of 5.3 mM is observed, what is the concentration of glucose (C₆H₁₂O₆) in mg/dL?
8. A throat spray is 1.40% by mass phenol, \(\ce{C_6H_5OH}\), in water. If the solution has a density of 0.9956 g/mL, calculate the molarity of the solution.
9. Copper(I) iodide (CuI) is often added to table salt as a dietary source of iodine. How many moles of CuI are contained in 1.00 lb (454 g) of table salt containing 0.0100% CuI by mass?
10. A cough syrup contains 5.0% ethyl alcohol, C₂H₅OH, by mass. If the density of the solution is 0.9928 g/mL, determine the molarity of the alcohol in the cough syrup.
11. D5W is a solution used as an intravenous fluid. It is a 5.0% by mass solution of dextrose (\(\ce{C_6H_{12}O_6}\)) in water. If the density of D5W is 1.029 g/mL, calculate the molarity of dextrose in the solution.
12. Find the molarity of a 40.0% by mass aqueous solution of sulfuric acid, \(\ce{H_2SO_4}\), for which the density is 1.3057 g/mL.

Solutions

1

• (a) The dilution equation can be used, appropriately modified to accommodate mass-based concentration units: \[\mathrm{\%\,mass_1 \times mass_1=\%\;mass_2 \times mass_2}\] This equation can be rearranged to isolate \(\mathrm{mass_1}\) and the given quantities substituted into this equation.
• (b) 58.8 g

3. \(\mathrm{114 \;g}\) 5. \(1.75 \times 10^{−3} M\) 7 \(\mathrm{95\: mg/dL}\) 9 \(\mathrm{2.38 \times 10^{−4}\: mol}\) 11 \(\mathrm{0.29 mol}\)