Question 1.      A typical air sample in the lungs contains oxygen at 100 mm Hg, nitrogen at 573 mm Hg, carbon dioxide at 40 mm Hg, and water vapor at 47 mm Hg.  What is the total pressure of air in the lungs?

P_oxygen = 100 mm Hg

P_nitrogen = 573 mm Hg

P_{carbon dioxide} = 40 mm Hg

P_{water vapor} = 47 mm Hg

P_total = P₁ + P₂ + …

P_total = P_oxygen + P_nitrogen + P_{carbon dioxide} + P_{water vapor}

P_total = 100 mm Hg + 573 mm Hg + 40 mm Hg + 47 mm Hg = 760 mm Hg

Question 2.      A 35.20 g sample of metal is heated to 100.0 °C and is then placed in a calorimeter containing 42.5 g of water at 19.2 °C.  If the final temperature of the metal and the water is 29.5 °C, what is the specific heat of the solid?  Assume no heat loss; the specific heat of water is 4.184 J/g °C.

m_metal = 35.20 g                       m_water = 42.5 g

T_{i metal} = 100.0 °C                    T_{i water} = 19.2 °C

T_{f metal} = 29.5 °C                      T_{f water} = 29.5 °C

c_metal = ?                                   c_water = 4.184 J/g °C               

q_in = - q_out           q = mc∆T

(m_metal)(c_metal)(∆T_metal) = (m_water)(c_water)(∆T_water)

(35.20 g)(c_metal)(29.5 °C – 100.0 °C) = - (42.5 g)(4.184 J/g °C)(29.5 °C – 19.2 °C)

(35.20 g)(c_metal)(-70.5 ° C) = - (42.5 g)(4.184 J/g °C)(10.3 °C)

(-2481.6 g °C)(c_metal) = - 1831.546 J

c_metal = 0.738 J/g °C

Question 3.      Calculate the amount of heat in calories required to vaporize 2.00 g of acetone, C₃H₆O, at 25 °C.  The heat of vaporization is 31.0 kJ/mol; the heat of fusion is 5.69 kJ/mol.

m = 2.00 g

T = 25 °C

∆H_vap = 31.0 kJ/mol

∆H_fus = 5.69 kJ/mol

q = m ∆H

 

Question 4.      Identify each as an ionic, molecular, network or metallic solid.

a.       silicon dioxide, SiO₂                                                         network solid

b.      titanium tetrachloride, TiCl₄                                             molecular solid

c.       cesium chloride                                                                 ionic solid

Question 5.      Name the types of intermolecular forces for each molecule:

a.       ethanol, CH₃CH₂CH₂OH             London-dispersion forces, dipole forces,

hydrogen bonding

b.      silicon dioxide, SiO₂                     London-dispersion forces

c.   carbon monoxide, CO                   London-dispersion forces, dipole forces

Question 6.      In hexane, C₆H₁₄, the intermolecular attraction is less than that in isopropyl alcohol, C₃H₇OH.  Predict which liquid has the higher value for each of the following:

1. vapor pressure                                                 hexane

2. viscosity                                                          isopropyl alcohol

3. boiling point                                                    isopropyl alcohol

4. surface tension                                                isopropyl alcohol

Question 7.      A tincture of iodine is prepared with 0.10 g I₂ and 10.0 mL ethyl alcohol, density of ethyl alcohol solution is 1.064 g/mL.  What is the solute, and what is the solvent?

                        Solute:             I₂                     Solvent:           ethyl alcohol

Question 8.      Would the following pairs of liquids be miscible or immiscible?

                        a.    carbon tetrafluoride, CF₄ and chloroform CHCl₃            miscible

                        b.    carbon tetrafluoride, CF₄, and water                               immiscible

Question 9.      What mass of solution containing 6.50% sodium sulfate, by mass contains 1.50g of sodium sulfate? 

m/m% = 6.50 % Na₂SO₄

m_solute = 1.50 g Na₂SO₄

m_solution = ?

10.  How many grams of Na₂SO₄ are required to prepare 25.00 mL of 0.200 M Na₂SO₄ solution?

11.  How many mL of 0.150 M CaCl₂ contain 6.00 g of CaCl₂?

12.  In 33.00 mL of 0.22 M (NH₄)₃PO₄, there are how many

a.       Moles of (NH₄)₃PO₄?

b.      Grams of phosphorous?

c.       Moles of phosphate ions?

d.      NH₄⁺ ions?

13.  A solution is prepared by dissolving 81.15 grams of Na₃PO₄·12H₂O in enough water to prepare 500.0 mL of solution.  The density of the solution is 1.077 g/mL.  Calculate

a.       The % anhydrous salt

b.      The % hydrated salt

c.       The molarity of Na₃PO₄

14.  If 15.00 g of a mixture of 25.00% CaCl₂ and 75.00% inert material are dissolved in 1.00 liter of water, how many mL of 0.500 M silver nitrate solution would be required to precipitate all of the chloride according to the equation: 

2 AgNO₃(aq)  +  CaCl₂(aq)  à  Ca(NO₃)₂(aq)  +  2 AgCl(s)

15.  A 1.00 gram sample of (NH₄)₂SO₄ is added to 50.0 mL of 0.450 M (NH₄)₃PO₄ solution.  Assuming no volume change, what are the resultant molarities of all ions in solution?

Mol  (NH₄)₂SO₄ = 1.00 g x 1 mol (NH₄)₂SO₄ /132.15g = 7.56e-3 mol (NH₄)₂SO₄

Mol (NH₄)₃PO₄ = 0.0500 L x 0.450 mol (NH₄)₃PO₄/L = 0.0225 mol (NH₄)₃PO₄

[NH₄⁺¹ ] = [2(7.56e-3 mol (NH₄)₂SO₄) + 3(0.0225 mol(NH₄)₃PO₄)]/0.0500 L = 1.65 M NH₄⁺¹

[SO₄^-2 ] = 7.56e-3 mol SO₄^-2 /0.0500 L = 0.151 M SO₄^-2

[PO₄^-3 ] = 0.0225 mol PO₄^-3/0.0500 L = 0.450 M PO₄^-3

16.  2.500 g of K₃PO₄ are dissolved in 100.0 mL of deionized water.  To this solution are added 75.00 mL of 0.300 M AgNO₃ solution.

                  K₃PO₄(aq)  +  3 AgNO₃(aq)  à  3 KNO₃(aq)  +  Ag₃PO₄(s)

            Initial   0.01178 mol   0.0225 mol

            Change   -X                 -3X                      +3X                         +X

X = 0.00750 mol

            Final    0.00428 mol       0 mol            0.0225 mol                  0.00750 mol

a.       How many grams of Ag₃PO₄ will precipitate?

b.      How many grams of which reactant remains unreacted?

c.       What is the final concentration of K⁺?

17.  When 35.00 mL of 0.100 M iron(III) chloride are added to 20.00 mL of 0.200 M potassium phosphate, a precipitate of iron(III) phosphate is observed to form.  Inventory the concentrations of all ions in solution and calculate the mass of the precipitate.

            Fe(Cl)₃   +   K₃PO₄    à      FePO₄    +   3   KCl

I	3.50 e-3 mol	4.00e-3 mol		0 mol	0 mol
x = 3.50 e -3 mol   D	-x mol	-x mol		+x mol	+3x mol
E	0 mol	5.0e-4 mol		3.5 e-3 mol	1.05 e-2 mol

[Fe⁺³] = 0M

[PO₄^-3] = 5.0 e-4/0.055 = 0.0091 M

[K⁺] = 3(4.00 e-3)/0.055 L = 0.218 M

[Cl^-] = 1.05 e-2/0.055 L = 0.191 M

3.5 e-3 mol FePO₄ x 150.82 g FePO₄/mol = 5.27 g FePO₄

18.  A 35.00 mL aliquot of 0.1861 M sulfuric acid is mixed with 20.00 mL of a 0.3016 M barium hydroxide solution.  Write the balanced chemical equation for the reaction and determine [H₃O⁺], [OH^-], [Ba⁺²], [SO₄^-2], pH, and pOH.  Find the mass of Barium sulfate that precipitates.

H₂SO₄  +  Ba(OH)₂  à  2 H₂O  +  BaSO₄(s)

	X = 6.032 e-3 mol

 

I	6.514 e -3 mol	6.032 e-3 mol			0 mol
D	-x mol	-x mol		+ 2x mol	+ 1x mol
E	4.82 e-4 mol	0 mol			6.032 e-3 mol

[Ba⁺²] = 0 M Ba⁺²

[SO₄^-1] = 4.82 e-4mol /0.05500 L = 8.18 e-3 M SO₄^-1

[H₃O⁺¹] = 2(4.82 e-4)/0.05500 L = 0.0175 M                         pH = 1.756

[OH^-1] = kw/[H₃O⁺¹] = 1.0 e-14/0.0175 = 5.7 e -13                           pOH = 12.24

mass BaSO₄ = 6.032 e-3 mol * 233.4 g/mol = 1.408 g BaSO₄

19.  Fill in the table below

Conjugate acid	Conjugate base
HC2H3O2	C2H3O2-1
HCN	CN-1
NH4+1	NH3
H3O+1	H2O
H2O	OH-1
CH3NH3+	CH3NH2

20.  Calculate the hydroxide ion concentration in a solution if 35.27 mL of it to exactly neutralize 24.30 mL of a 0.07243 M solution of sulfuric acid.

21.  A solution is prepared by dissolving 0.1162 grams of KOH in 250.0 mL of solution.  Calculate

a.       [H⁺] = 1.2107e-12

b.      [OH^-] = 8.284e-3

c.       pH = 11.9182

d.      pOH = 2.0818

22.  Fill in the table below

[H3O+]	[OH-]	pH	pOH
3.582 x 10-6	2.792e-9	5.4459	8.5541
1.539e-6	6.498 x 10-9	5.8128	8.1872
1.705e-4	5.864e-11	3.7682	10.2318
2.986e-5	3.349e-10	4.5249	9.4751

23.  A primary standard is made by dissolving 3.7627 grams of oxalic acid dihydrate in enough water to make 500.0 mL of solution.  A 25.00 mL aliquot of the oxalic acid solution requires 41.87 mL of potassium hydroxide solution to titrate it to a phenophalein end point.  A 25.00 mL sample of vinegar is titrated with 15.97 mL of the sodium hydroxide solution.  What is the concentration of acetic acid in the vinegar?

Concentration of oxalic acid standard

Concentration of potassium hydroxide solution

Concentration of Acetic acid

24.  Solution A is a solution of HNO₃ with a pH of 2.80.  Solution B is a solution of NaOH with a pH of 11.30.  Calculate the pH of the following solutions:

Solution A pH = 2.80                                                             [H₃O⁺] = 10^-2.80 = 1.6e-3 M

Solution B pH = 11.30            pOH = 2.70                 [OH^-1] = 10^-2.70 = 2.0e-3 M

a.       10.00 mL of A and 5.00 mL of B

            HNO₃  +  NaOH    à    H₂O    +    NaNO₃

I	1.6e-5 mol	1.0e-5 mol
D	-x mol	-x mol
E	0.6e-5 mol	0 mol

[H₃O⁺] = 0.6 e-5mol/0.015 L = 4e-4 M

pH = 3.40

b.      10.00 mL of B and 5.00 mL of A

            HNO₃  +  NaOH    à    H₂O    +    NaNO₃

I	0.8e-5 mol	2.0e-5 mol
D	-x mol	-x mol
E	0mol	1.2e-5 mol

[OH^-1] = 1.2 e-5mol/0.015 L = 8e-4 M

pOH = 3.10

pH = 10.90

c.       How many mL of A must be added to 25.00 mL of B to make a solution of pH = 7.00?

pH = 7 when {H₃O⁺] = {OH^-1] at the equivalence point of a titration

We need to find out how many mL of A are required to completely react with 25.00 mL of B

25.  What is the pH and pOH of a solution prepared by dissolving 2.5 g hydrochloric acid, HCl, in water to make 425 mL of solution?    

pH = - log[H⁺] = - log(0.16) = 0.792

pH + pOH = 14.000 à pOH = 14.000 – pH = 14.000 – 0.792 = 13.208