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Final Exam Review 2A - Introduction to Chemistry | CHEM 100, Exams of Chemistry

Imperial Valley CollegeChemistry

Material Type: Exam; Class: Introduction to Chemistry; Subject: Chemistry; University: Imperial Valley College; Term: Unknown 1989;

Typology: Exams

Pre 2010

Uploaded on 08/18/2009

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koofers-user-zlx 🇺🇸

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Chem 2A Final Review
------------------------------ Potentially Useful Information for the Problems
Below------------------------------
pKb of dimethylamine = 5.9 10-4
R=0.0821 (atm L)/(mol K)
--------------------------------------------------------------------------------------------------
1. An acidic solution has a pH of 3.43. What is the Hydronium ion concentration?
Ans. [H3O+] = 3.7 10-4
What is the [OH-] concentration?
pKw = pH + pOH
14 = 3.43 + pOH
pOH=10.57
pOH=-log[OH-]
-antilog (pOH)=[OH-]
=2.69 10-11
2. What is the pOH of 0.050 M dimethylamine, a weak base?
Me2NH + H2O Me2NH2+ + OH-
Kb = [Me2NH2+ ] [OH-] / [Me2NH]
X2 = [(5.9 10-4) (0.050)]-1/2 = 0.0054
pOH = -log(0.0054) = 2.26
pH = 11.73
3.
4.
5. Rank the following from lowest to highest acidity.
1.8 10-5
1.0 10-10
1.2 10-2
8.0 10-9
6. In the following reaction what is (are) the base(s) and the acid(s)?
1
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe

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Chem 2A Final Review ------------------------------ Potentially Useful Information for the Problems Below------------------------------ pKb of dimethylamine = 5.9  10 - R=0.0821 (atm L)/(mol K)

  1. An acidic solution has a pH of 3.43. What is the Hydronium ion concentration? Ans. [H 3 O+] = 3.7  10 - What is the [OH-] concentration? pKw = pH + pOH 14 = 3.43 + pOH pOH=10. pOH=-log[OH-] -antilog (pOH)=[OH-] =2.69  10 -
  2. What is the pOH of 0.050 M dimethylamine, a weak base? Me 2 NH + H 2 O  Me 2 NH 2 +^ + OH- Kb = [Me 2 NH 2 +^ ] [OH-] / [Me 2 NH] X^2 = [(5.9  10 -4) (0.050)]-1/2^ = 0. pOH = -log(0.0054) = 2. pH = 11.
  5. Rank the following from lowest to highest acidity. 1.8  10 - 1.0  10 - 1.2  10 - 8.0  10 -
  6. In the following reaction what is (are) the base(s) and the acid(s)? 1

3HCl + Al(OH) 3  3H 2 O + AlCl 3

  1. In the following reaction what are the initial acid and base HCl + Mg(OH) 2  MgCl 2 + H 2 O
  2. Determine the number of moles of carbon dioxide produced in the following unbalanced combustion reaction. C 8 H 17 OH + O 2  CO 2 + H 2 O Ans = 8 moles
  3. How many grams of NaH 2 PO 4 are needed to react with 0.0106 moles of NaOH in the balanced reaction:

NaH 2 PO 4 + 2NaOH  Na 3 PO 4 + 2H 2 O

NaH 2 PO 4 = 119.98 g/mol NaOH = 40.00 g/mol Ans 0.

  1. In the following balanced reaction 8.00 g of oxygen is used to produce how many grams of HCN?

2NH3(g) + 3O2(g) + 2CH4(g)  2HCN(g) + 6H 2 O(l)

ans 4.

  1. A gas has a volume (in Liters) of 6.00 liters at 27 C with a pressure of 1.0 atm. What is the volume of the gas at 327 C with a pressure of 3.00 atm. Ans. 4.
  2. When 35.6 L of ammonia is reacted with oxygen at 1.0 atm at 25 C, the answer closest to the number of grams of H 2 O produced in the unbalanced equations is: 4NH 3 + 5O 2  4NO + 6H 2 O PV=nRT n = PV/RT=1 35.6 /0.0821 (25+273) =
  3. The answer closest to the number of grams of NaH 2 PO 4 needed to react with 38.74 mL of 0.275 M NaOH, according to the following balanced equation is: (NaH 2 PO 4 = 119.98 g/mol) NaH 2 PO 4 (s) + 2NaOH (aq)  Na 3 POH 4 (aq) + 3H 2 O Ans.0. 2

heat absorbed = specific heat * mass * temp change 9.80  103 cal/(g C)

  1. Express 96,342 m using two significant figures 9.60  104 m 9.6  104 m 9.60  10 -4^ m 9.63  104 m 9.60  104 m
  2. The largest volume among the following is 10 nL 10,000 L 1,000 pL 0.01 dL 100 mL
  3. The symbol A=37, Z=17, X-^ (where X stands for the element symbol) represents an ion of chlorine with 20 electrons chlorine with 16 electrons rubidium with 38 electrons rubidium with 36 electrons chlorine with 18 electrons
  4. The most likely ionic form of the elements Ca and F is: Ca2-, F+ Ca2+, F2- Ca2+, F- Ca+, F- Ca+, F2-
  5. Convert 233. C to Fahrenheit.
  6. F
  7. F
  8. F 4

130. F

273. F

  1. The density of Au is 19.3 g/mL. How many 1-ounce coins could be manufactured from a 1 cubic foot block of gold? 1 ft^3 = 0.02832 m^3 , 1 oz = 28.35 g 1.93  104 3.32  102 2.43  1010 7.30  105 8.21  10 -
  2. A metal has a charge of 3+ and 39 electrons. The mass of one of its 7 isotopes is 96 amu and its abundance is 74.8%. Calculate the number of neutrons for this element and what is the element? neutrons = 19, Cl neutrons = 47, Kr neutrons = 54, Kr neutrons = 54, Mo neutrons = 54, Nb
  3. A box of dimensions 2.00 inches  3.50 inches  2.500 inches (1 inch = 2.54cm) has a volume closest to 0.2868 L 17.5 L 0.287 L 0.04445 L 0.0444 L 30.. Determine the number of moles of carbon dioxide produced in the following unbalanced combustion reaction. C 8 H 17 OH + O 2  CO 2 + H 2 O 2 5

CO

H 2

None of these

  1. The volume of 0.100 M Ba(OH)2(aq) solution needed to prepare 6.30 L of 0.003 M Ba(OH)2(aq) solution is 6.3 L 0.189 L 33.3 L 0.03 L 3.0 L
  2. The chemical formula for a compound with the empirical formula C 7 H 4 O 2 and a formula weight of 240.2 g/mol is C 7 H 4 O 2 C 13 H 4 O 5 C 21 H 12 O 6 C 14 H 8 O 4 C3.5H 2 O
  3. The formula of Vitamin C is C 6 H 8 O 6. How many moles of Vitamin C are there in two 500 mg tablet?

2.84  10 - 5.68  10 -

  1. The number of chlorine atoms in one mole of aluminum chloride is approximately: 3

6.02  1023 18.06  1023 2.01  1023 7

  1. Potassium nitrate decomposes on heating, producing potassium oxide, gaseous nitrogen and gaseous oxygen. Choose the closest number of grams of KNO 3 that must decompose in order to produce 1.35 g of O 2 (in the original exam the chemical formula was given…but I want you to write chemical equation for practice).
  7. The density of mercury (Hg) is 13.5 g/mL. If a chemist wants to add 2.00 moles of Hg to a reaction vessel, how many milliliters should he add? 401

7.38  10 -4^ mL

  3. If 2.50 moles of H 2 reacts with Cl 2 to form HCl according to the following unbalanced equation, what number below is closest to the number of moles of HCl produced? H2(g) + Cl2(g)  HCl(g)
  8. 8
  1. Calculate the number of grams of solute in the following: 50.0 mL of a 12.0 M HNO 3 solution M = mol/L, mol = M  L, 50.0 mL  1L/1000mL  12.0 M = 0.600 mol HNO 3 , mol = g/mw, g = mol  mw = 0.600 mol  63.01 g / mol = 37.81 g HNO 3
  2. Calculate the number of grams of solute in the following: 1.20 L of a 0.0032 M Na 2 SO 4 solution M = mol/L, mol = M  L = 1.20 L  0.0032 M = 0.0038 mol Na 2 SO 4 , mol = g /mw, g = mol  mw = 0.0038 g/mol  142.04 g/mol = 0.545 g
  3. Calculate the molarity of the following: 14.0 g silver Nitrate (AgNO 3 ) in 1.00 L of solution. Mol = g  mw = 14.0 g  mol/169.87 g = 0.0824 mol, M = mol/L = 0.0824 / 1.00 L = 0.0824 M Calculate the molarity of the following: 0.025 mol of potassium chloride (KCl) in 50.0 mL of solution M = mol/L = 0.025 mol / (50.0 mL  1L/1000mL) = 0.500 M
  4. In a dialyzing bag containing colloidal-sized proteins, glucose and NaCl is place in pure water, describe what would happen.
  5. Calculate the Osmolarity for: a) 3 M K 3 PO 4 Osmolarity = molarity  i = 3  4 = 12 b) 6 M protein Osmolarity = molarity  i = 6  1 = 6 c) what is the Osmolarity by combining the two above examples? 6 + 12 = 18
  6. Why is the freezing point of a solution of MgCl 2 lower then a solution of NaCl?
  1. Determine the final concentration of a solution by adding 45 mL of water to 90.0 mL of a 3.0 M NaCl solution. M1V1=M2V2, M2 = M1V1/V2 = 90 mL  3/45 mL = 6.0 M
  2. Determine how many L of water must be added to 34.5 mL of a 12.0 M solution of nitric acid (HNO 3 ) to make a 4.0 M solution. M1V1= M2V2, V2 = M1V1/M2 = 34.5 mL  12/4 = 103.5 mL = 0.104 L
  3. Classify the following reaction as either a combination, decomposition, single replacement, or double displacement reaction. a) 2NaHCO 3  Na 2 CO 3 + CO 2 + H 2 O b) 2Fe + 3Cl 2  2FeCl 3
  4. Which of the following is Not a redox reaction? a) 2CuO  2Cu + O 2 b) 2KclO 3  2KCl + 3O 2 c) CaCO 3  CaO + CO 2 ans C
  5. Determine the oxidation number (oxidation state) of all the elements in the following reactions. a) Mg + 2HCl  MgCl 2 + H 2 b) 2SO 2 + O 2  2SO 3 c) 2Fe 2 O 3 + 3C  4Fe + 3CO 2
  6. Which species (elements) are oxidized and which are reduced in the following reaction. a) Zn + CuCl 2  ZnCl 2 + Cu b) 3H 2 S + 2HNO 3  3S + 2NO + 4H 2 O c) 2FeBr 3  2FeBr 2 + Br 2
  7. What effect would this have on the rate of a reaction:

Lewis Structure  VESPR Class name  VESPR Molecular Shape name Polarity Solubility: the phenomena is Likes Dissolve Likes, the fact is molecules dissolve if they have the same solubility Melting and Boiling Points Mole Amu, Molar Mass Empirical and Molecular Formula Balancing Chemical Formulas Limiting Reagents Theoretical and Percent Yield

  1. The answer that is closest to the number of grams of oxygen in 6.022  1023 molecules of O 2 is:
    1. 1.0 4) 64.
    2. 16.0 5) 6.022  1023
  2. Both water and sulfur dioxide are produced from the reaction of sulfuric acid (H 2 SO 4 ) with copper metal in the following balanced equation. How many moles of H 2 O will be produced at the same time that 10.0 moles of SO 2 is produced? 2H 2 SO 4 + Cu  SO 2 + 2H 2 O + CuSO 4
    1. 5 4) 25
    2. 10 5) 30
    3. 20
  3. Chlorophyll, essential to plants for photosynthesis, contains one magnesium atom, three oxygen atoms, four nitrogen atoms, thirty three carbon atoms and twenty nine hydrogen atoms. What is the chemical formula for chlorophyll?
  1. FeO 3 N 4 Ca 33 Hy 29
  2. Mn3O4N33C29H
  3. NaO 3 Ni 4 Ca 33 H 29
  4. MgO 3 N 4 C 33 H 29
  5. MnO 3 N 4 C 33 H 29
  1. Vitamin C (mw = 176.12 g/mol) contains 40.9% C, 4.6% H and 54.5% O. What is the molecular formula of Vitamin C
  2. If there are 2.62 ^1022 atoms in 1.00 g of sodium and they are lined up side by side, what is the length of the line of sodium atoms in miles? Assume that the atoms are spheres of diameter 0.372 nm.
  3. Mystery element X combines with sulfur to form the compound X 4 S 3. The molecular mass of X 4 S 3 is 220.09 amu. Mystery element X is:
  4. What is the percent yield of sodium carbonate if 1.254 g of sodium hydrogen carbonate (84. g/mol) decomposes to give 0.765 g of sodium carbonate (105.99 g/mol)? 2NaHCO 3 (s)  Na 2 CO 3 (s) + H 2 O (g) + CO 2 (g)
  1. 48.4%
  1. What mass of BaSO 4 is produced by starting with 12.1 g of Fe 2 (SO 4 ) 3 , in the following balanced reaction? 3BaCl 2 (aq) + Fe 2 (SO 4 ) 3 (aq)  3BaSO 4 (s) + 2FeCl 3 (s)
  1. 8.98  10 -4^ 4) 4.
  2. 2.34 5) 21.
  1. Draw the Lewis dot structure for Barium, Lead, Bismuth, Polonium, and Radon
  2. Draw the structure with no double bonds. SOF3-^ (S is the central atom)
  3. Draw a 3-D diagram for each molecule and indicate if the molecule is polar or non-polar. a. OF 2 b. PBr 3
  4. Draw the 3-D structure. Give the VSEPR electron-pair name, the molecular shape name for the following. a. NF 3 b. CCl 4 c.

CF 3

  1. Draw and example of hydrogen bonding between NH 3 and HF
  2. Would you expect the following pairs to be soluble with each other? a. CH 4 with H 2 O b. with CH 2 F 2 C O H H H H