Practice Final Dr. Garces' General Chemistry 200

Although I have tried to make sure that the answers are correct, there may be typos. In this sample test, it is important to understand the underlying concept of each question.

1 A piece of metal has a mass of 1.01•10-2 Kg. When it was placed in a 100-ml graduated cylinder containing 30.0 ml

of water, the volume of water increased to 32.3 ml. What is the density of the metal (g / ml), using the correct number of significant figures 4.4 g/ml

2 What is the number of square decimeters in 6.82 square centimeters? 0.0682 dm2

3 Which of the following is/are compound(s): blood, orange juice, diamonds, gasoline, rust. Rust

4 Name an experimental technique to separate ethanol from water. Distillation

5 What was Rutherford's contribution to the model of the atom? Dense nucleus

6 Which pair demonstrate the law of multiple proportion: NH4 and NH4Cl or NO and NO2 NO and NO2

7 A 50.0 g drug sample was analyzed and found to contain C (24.75 g), N (14.40 g), H (2.60 g) and O (8.25 g). Calculate the empirical formula. If there are exactly 4 nitrogen atoms in the molecular formula of this compound, what is the molar mass of this compound? C8N4H10O2

8 In an atom which particle are in the same amount? protons and electrons

9 If 62.0 grams of sodium oxide reacts with excess dihydrogen oxide, how many molecules of sodium hydroxide can theoretically be produced? 12.04•1023molc

10 Balance the following equations.

A ___KOH(aq) + ___H2SO4(aq) à ___ K2SO4 (aq) + ___H2O (g) 2-1-1-2

B ___C4H14 (l) + ____O2 (g) à ___CO2 (g) + ____ H2O (l) 2-15-8-14

Identify the neutralization and the combustion reaction above.

11 For the reaction: ___Mg2Si(s) + ___H2O(l) à ___Mg(OH)2(aq) + ___SiH4(g)

Which of the reactants is in excess if 40.0 g of Mg2Si is combined with 50.0 ml of H2O. Assume the density of water is 1.00 g/ml. H2O

12 For the reaction shown below, if the actual yield of Fe2O3 is 45% of the theoretical yield, what mass of iron (in kg) is needed to produce 400 g of Fe2O3 : Fe (s) + O2 (g) à Fe2O3 (g) 621.6 g

13 Sulfur (32S2-) has how many different subatomic particles ? 16p, 18e, 16n

14 If an isotope has a mas number of 15 and 8 neutrons, what is the element? N

15 Ethyl alcohol (booze), C2H5OH, also called grain alcohol, can be made by the fermentation of glucose, C6H12O6, which often comes from starch in grain: _C6H12O6 (aq) à _C2H5OH(l) + _CO2 (g) Determine the maximum mass (theoretical yield) of ethyl alcohol which could be produced from 750 g of glucose. If 150 L of CO2 (g) is collected after the fermentation, what is the % yield. Assume the density of CO2 (g) is 1.96 g/ L. 80.4%

16 Classify the following as endothermic or exothermic reactions and determine the sign for D H.

Process or the system of interest exothermic or endothermic D H

ice melts

electron relaxes back to the ground state

Fog collects on your car window

17 Write the chemical formula for the following

Nitrate ion aluminum oxide copper(II) iodide Tin(II) phosphate

18 The atomic mass of bromine is 79.99 amu. The isotope bromine-79 and bromine-81 exist in nature in what approximate ratio - 50.5 % (Br-79):49.5% (Br-81)

19 Write the net ionic equation for any reaction that occurs upon mixing each pair.

(a) silver nitrate and barium chloride

(b) Hydrochloric acid and strontium hydroxide. H+ (aq) + OH-(aq) à H2O(l)

20 A 125 ml solution of HBr is titrated with 160 ml 0.500M Ca(OH)2 solution to the equivalent point. What was the molarity of the HBr solution? 1.28M

21 (Did not cover) A 0.47-g sample of zinc reacts with 200.00 g of dilute HCl in a coffee cup calorimeter to form zinc(II)chloride. If 13 J of heat is release and the initial temperature of the water is 20.0 °C, what is the final temperature after the reaction? Assume that the mixture has the same specific heat as water.

35.67°C

22 Calculate D H° for the reaction: H(g) + F(g) à HF (g ) From the following heats of reaction:

H2 (g) à 2 H (g) D H° = 436.4 KJ

F2 (g) à 2 F (g) D H° = 192.5 KJ

H2 (g) + F2(g) à 2HF (g) D H° = -104 KJ 366.5 kJ

23 How many oxygen atoms are there in 1.55 ng of Ca3(PO4)2 ? 2.41•1013

24 Use the kinetic molecular theory to explain Charles Law and Boyle's Law.

25 Calculate the density of ammonia in grams per liter (g/L) at 752 mmHg and 55 °C.

26 How many electrons in an atom can have the quantum numbers n=3, l=2 ? 10

27 Order the following in increasing rate of effusion: CH3 NO F2 NO2 Cl2

(Slowest) Cl2 - NO2 - F2 - NO - CH3 (Fastest)

28 The "b" term in the Van der Waal equation corrects what parameter in the Ideal Gas Law ?

29 Exactly 10 ml of gas A (MWt. = 15.0 g/mol) effuse through an opening in 2.0 sec. Exactly 10 ml of gas B effuse through the same opening in 8.0 sec. What is the molar mass of gas B ? 240 g/mol

30 Nitric oxide (NO) reacts with molecular oxygen as follows:

2NO (g) + O2(g) à 2NO2(g)

Initially NO and O2 are separated as shown below. When the valve is opened, the reaction quickly goes to completion. Determine what gases remain at the end and calculate their partial pressure. Assume that the temperature remains constant at 25° C.

. PO2 = 0.167 atm, PNO2=0.167 atm

4.00 L0.500 atm

2O2.00 L1.00 atm

NO

31 (Did not cover) A calorimeter has a heat capacity of 2.47 kJ/K. When a 0.105-g ethylene (C2H4) is combusted in

this calorimeter, the T increases by 2.14 K. What is the DHcombustion for 1-mol of ethylene ? -1.41•10-31 kJ

32 What is the heat capacity of a 1.00kg substance which absorbs 30.7Kcal upon heating from 300K to 910K ?

33 What is the de Broglie’s l of an e- (m = 9.1 •10-28 g) moving at 1.0 •10-3 times the speed of light ? 2.4nm

34 What is the electron configuration of an element with atomic number 109?

35 Name three ions with the following electron configuration: [Kr] 4d6

36 I.P. is always a positive quantity, whereas E.A. may be either positive or negative. Explain.

37 As a group, the noble gases are very stable chemically (only Kr and Xe are known to form compounds). Why ?

38 For the following orbitals: 3px, 3s, 3dxz, 4s, 4dz2, 3py, 3dyz

a) Arrange the following orbitals in order of increasing energy

b) Sketch W2 (electron radial probability) for the 3py orbital.

39 Which atoms between H and Kr which begins with the letter N are paramagnetic?

40 In general, atomic radius and ionization energy have opposite periodic trends. Why ?

41 Draw a picture of a Hydrogen atom and show the following transitions in your diagram:

a) ni = 4 nf = 3 b) ni = 4 nf = 1

(i)Calculate the wavelength for a. (ii) Calculate the energy for b.

42 Arrange the following anions in order of increasing size: O2- Te2- Se2- S2-

43 For each pair of ionic compound, which has the higher lattice energy: (i) KCl or MgO (ii) Mg3N2 or LiCl

44 Write the Lewis structure and molecular geometry for XeCl2, HCO2- and N2F2 .

What are the bond angles, hybridization and polarity of each?

45 Br2 and ICl have almost the same molar masses, yet Br2 melts at -7.2°C, whereas ICl melts at 27°C. Explain.

46 Out door pipes have to be drained or insulated in cold climates. Why?

C H 3 N C H 3C H 3

C H 3 C H 2 N HC H 3

BP = 35°CBP = 3°C

47 Arrange the following in order of increasing boiling point: RbF, CO2, CH3OH, CH3Br. Explain your choice.

48 A glass can be filled slightly above the rim with water. Explain why the water does not overflow ?

49 Why does viscosity of a liquid decrease with increasing temperature ?

50 The boiling point and freezing point of sulfur dioxide are -10°C and -72.7°C (at 1 atm), respectively. The triple point is -75.5°C and 1.65•10-3 atm, and its critical point is at 157°C and 78 atm. On the basis of this information, draw a rough sketch of the phase diagram of SO2.

51 The following compounds have the same molecular weights. Explain why one of these compounds has a higher boiling point than the other?