General Chemistry I
Chapter 1 -16 Practice questions
1 a) Find the % by mass of each element in barium hydrogen sulfate.(5p)
b) A sample of a compound is found to contain 0.97 g of phosphorous and 1.25 g of oxygen. If 0.02 moles of this compound weight 5.68g, calculate its molecular formula.
2 A 99.8-mL sample of a solution that is 12.0 % KI by mass(d=1.093 g/mL) is added to 96.7 mL of another solution that is 14.0 % Pb(NO3)2 by mass (d=1.134 g/mL). How many grams of PbI2 should form?
Pb(NO3)2(aq) + KI(aq) PbI2(s) + KNO3(aq)
- a) Nitric acid is a good oxidizing agent, its product depends on the concentration of the acid and the strength of the reducing agent. Write the balanced equation for the half reactions and for the overall reaction, for following reaction.
Cu(s) + NO3-(aq) Cu2+(aq) + NO(g)
b) How many milliliters of 0.2155 M KOH(aq) are required to titrate 25.00 mL of 0.3057 M
HC3H5O2(aq).
- The mixture of 0.6 moles of N2 and 0.6 moles of H2 gases are mixed to give NH3 gas. The reaction
occurs in a closed container. The pressure and temperature are 720 mmHg and 27 ºC before the
reaction. If temperature is increased to 127 ºC. What will be the pressure in mmHg in the container
after the reaction.
- The titration of 50.0 mL of a saturated solution of sodium oxalate, Na2C2O4 requires 25.8 mL of 0.02140 M KMnO4 in acidic solution. What mass of Na2C2O4, in grams, would be present in 1.00 L of this saturated solution?
C2O42- + MnO4- Mn2+ + CO2(g)
- The reaction of 15.0 g C4H9OH, 22.4 g NaBr, and 32.7 g H2SO4 yields 17.1 g C4H9Br in the reaction
C4H9OH + NaBr + H2SO4 C4H9Br + NaHSO4 + H2O
What are (a) the theoretical yield, (b) the actual yields, and (c) the percent yields of this reaction?
- Balance the following equations for redox reaction occurring in acidic and basic solution respectively.
(a) S2O32- + Cl2 (g) SO42- + Cl- (Acidic solution)
(b) S8(s) S2- + S2O32- (Basic solution)
- 3 g of CaCO3 reacts with 150 mL of 0.2 M HCl,
a)Write the ionic and net ionic equations.
b)Find the volume of dry gas produced at STP.
c)Find the molarity of all ions remaining.
d)Find the volume of wet gas produced at 35 ºC and 760 mmHg pressure.
Vapor pressure of H2O at 35 ºC is 40 mmHg.
- Find ΔH for the reaction of :
2B(s) + 3H2(g) B2H6(g)
When the following in formations are given,
B2O3(s) 2B(s) + 3/2 O2(g) ΔH = 1273 kJ
B2O3(s) + 3H2O(g) B2H6(g) + 3O2(g) ΔH = 2035 kJ
H2(g) + 1/2O2(g) H2O(l) ΔH = - 286 kJ
H2O(g) H2O(l) ΔH = - 44 kJ
- Write the balanced chemical reactions for each of the following
i)Elemental phosphorus (P4) burnt in excess oxygen to give tetraphosphorusdecaoxide.
ii)The formation of lead(II)oxide, nitrogen dioxide and oxygen by heating leadnitrate.
iii)The neutralization of potassium hydroxide and sulfuric acid ( with also the ionic and net ionic
equations).
- a) Classify the following molecules and ions using VSEPR notation and describe their shapes.
i) NCl3 ii) OH- iii) AsCl3 iv) PH+ v) OCl2
b)Write the balanced equation for the half reactions and for the overall reaction, for following
reaction.
Sb2S3 + NO3- Sb2O5 + SO42- + NO2
- a) Which of the following species would you expect to be diamagnetic and which paramagnetic?
i) K+ ii) Cr3+ iii) Zn2+ iv) Cd v) Co3+ vi) Sn2+ vii) Br
b) Arrange the following in expected order of increasing radius : Br, Li+ , Se, I- explain your
answer.
- a) What is the shape of each of the following molecules? In each case what set of hybrid orbitals on
the central atom may be used to contract an appropriate set of localized bonding orbitals?
SiF4, AlCl3, BeCl2, ClF3, BrF5
b)Which of the following molecules will have a dipole moment and which will not?
CS2, BeCl, SnCl2, H2S, SCl2
- The reaction between NO and H2 is believed to occur in the following three-step process
NO +NO N2O2 ( fast)
N2O2 + H2 N2O +H2O (slow)
N2O + H2 N2 + H2O (fast)
a)Write a balanced equation for the overall reaction
b)From the mechanism represented above, a student correctly deduced the rate law for the reaction is rate =k[NO]2[H2]. The student then concludes that (1) the reaction is third-order and (2) the mechanism involves the simultaneous collision of two NO molecules and an H2 molecule. Are conclusions (1) and (2) correct? Explain.
c)Explain why an increase in temperature increases the rate constant, k, given the rate law in (c).
- With the following data, calculate Hf o for 1 mol MgCl2(s). Explain why you would expect
MgCl2 to be more stable a compound than MgCl. First ionization energy of Mg(g) = +738 kJ/mol ;
Second ionization energy of Mg(g) : +1451 kJ/mol ; Lattice energy of MgCl2(s) = - 2526 ; Enthalpy
of sublimation of Mg(s) = +146 kJ/mol ; Enthalpy of dissociation of ½ mol Cl2(g) = +122 kJ;
Electron affinity of Cl(g) = - 349 kJ/mol; Lattice energy of 1 mol MgCl(s) = - 676 kJ/mol
16. A solution of 2.95 g sulfur in 100 g of cyclohexane had a freezing point of 4.18 C. The freezing
point of pure cyclohexane is 6.50 C. What is the molecular formula of sulfur in this solvent?
(Kf = 20.2 C. kg .mol –1 and atomic mass of sulfur is 32.06 u).
17. Draw the phase diagram of water and CO2.
18. The two solution pictured here are separated by a semi-permeable membrane that permits only the
passage of water molecules. In what direction will a net flow of water occur, that is, from left to right or right to left?
? H2O
H2O ?
19. Propose a hybridization scheme to account for bonds formed by the central carbon atom in
each of the following molecules : (a) hydrogen cyanide, HCN; (b) methyl alcohol, CH3OH;
(c) acetone (CH3)2CO; (d) carbamic acid, H2NCOOH
20. With the following data, calculate Hf o for 1 mol CaCl2(s). First ionization energy of Ca(g) = + 590
kJ/mol ; Second ionization energy of Ca(g) : +1145 kJ/mol ; Lattice energy of CaCl2(s) = - 2223; Enthalpy of sublimation of Ca(s) = +178.2 kJ/mol ; Enthalpy of dissociation of ½ mol Cl2(g) = +122 kJ; Electron affinity of Cl(g) = - 349 kJ/mol;
21. a) A 0.72 g sample of polyvinyl chloride (PVC) is dissolved in 250.0 mL of a suitable solvent at
25 C. The solution has an osmotic pressure of 1.67 mmHg. What is the molar mass of the PVC
b) What are the partial and total vapor pressure of a solution obtained by mixing 35.8 g benzene
C6H6 and 56.7 g toluene, C7H8, at 25 C? Vapor pressure at 25 C : C6H6 = 95.1 mmHg ;
C7H8 = 28.4 mmHg. (Atomic mass of C: 12.0 u, H: 1.0 u)
22. For the reaction A + B C + D the following initial rates of reaction were found. What is the
rate law for this reaction and what is the value of the rate constant, k ?
______
Experiment[A], M [B],MInitial rate, M s-1
______
1 0.50 1.50 4.2x10-3
2 1.50 1.50 1.3x10-2
3 3.00 3.00 5.2x10-2
______
KİM 109-01,02
II. Mid term.
10 May 1999
Name and Surname :
No :
Signature :
1.In the Ostwald process for oxidizing ammonia, a variety of products is possible – N2, N2O, NO, and NO2 – depending on the conditions. One possibility is
NH3(g)+ 5/4O2(g) NO(g) + 3/2H2O(g) Kp (atm) = 2.11 x 1019 at 700 K
For the decomposition of NO2 at 700 K
NO2(g) NO(g) + 1/2 O2(g) Kp(atm) = 0.524
a)Write a chemical equation for the oxidation of NH3(g) to NO2(g).
b)Determine Kp for the chemical equation you have written.
- Given the equilibrium constant values
N2(g) + ½ O2(g) N2O(g) Kc = 2.7 x 10–18
N2O4(g) 2NO2(g)Kc = 4.6 x 10-3
½ N2(g) + O2(g) NO2(g)Kc = 4.1 x10-9
Determine a value of Kc for the reaction
2N2O(g) + 3O2(g) 2N2O4(g)
- What is the (a) degree of ionization and (b) percent ionization of trichloroacetic acid in a 0.035 M
HC2Cl3O2 solution?
HC2Cl3O2 + H2O H3O+ + C2Cl3O2- pKa = 0.52
- A particular household ammonia solution (d= 0.97 g/mL) is 6.8 % NH3 by mass. How many milliliter of this solution should be diluted with water to produce 625 mL of a solution with
pH = 11.25?
- Determine the following characteristics of the titration curve for 20.0 mL of 0.275 M NH3(aq) titrated with 0.325 M HI(aq).
(a)The initial pH.
(b)The volume of 0.325 M HI(aq) at the equivalence point.
(c)The pH at the equivalence point.
- A solution of 75.0 mL volume is prepared containing 15.5 mmol HCHO2 and 8.5 mmol NaCHO2.
(a)What is the pH of this solution?
(b)If 0.25 mmol Ba(OH)2 is added to the solution, what is the pH.
- Should precipitation occur in the following cases?
(a)0.1 mg NaCl is added to to 1.0 L of 0.1 M AgNO3(aq).
(b)One drop(0.05 mL) of 0.1 M KBr is added to 250 mL of a saturated solution of AgCl.
Ksp(AgCl) : 1.8 x10-10 Ksp(AgBr) : 5.0 x 10-13
- (a) Should precipitation of MgF2(s) occur if a 22.5 mg sample of MgCl2 is added to 325 mL of
0.035 M KF? (b) What is the minimum pH at which precipitation of Cd(OH)2(s) will occur from a solution that is 0.0055 M in Cd2+(aq)?.
Ksp(MgF2) : 3.7 x10-8Ksp(Cd(OH)2 : 2.5 x10-14