multiple choice typa questions
Define Homogenous Equilibria or Heterogeneous Equilibria (choose one)
Equilibria in which all entities are in the same phase.
or
Equilibria in which reactants and products are in more than one phase.
write the equilibrium law equations for the following reaction:
3 Zn (s) + 2 CrBr3 (aq) = 2 Cr(s) + 3 ZnBr2 (aq)
K= [Zn(aq)]3 / [Cr(aq)]2
calculate the solubility of zinc hydroxide at 25*C. the Ksp of Zn(OH)2 (s) is 4.5 x 10-17
[ Zn 2+ (aq) ] = 2.24 x 10-6 mol / L
[ OH - (aq) ] = 4.48 x 10-6 mol / L
a 1.0 L buffer is prepared, contains 0.20 mol /L of acetic acid and 0.20 mol / L of sodium acetate at equilibrium. what is the pH of the buffer?
pH = 4.74 (approx.)
explain how each of the following affect the amount of Oxygen gas:
4 HCl(g) + O2 (g) = 2 H2O (g) + 2 Cl2 (g) +114.4 KJ
a) rising the temperature of the mixture
b) introducing more steam
c) increasing the pressure
d) addition of a catalyst
e) decreasing the volume
a) shift towards reactants in terms of oxygen gas
b) shift towards reactants in terms of oxygen gas
c) shift towards products in terms of oxygen gas
d) no shift of equilibrium in terms of oxygen gas
e) shift towards products in terms of oxygen gas
define "common ion effect"
A reaction in the solubility of a salt caused by the presence of another salt having a common ion
a soluton is made by dissolving 0.80g of Ca(OH)2 (s) in water to make 110 mL of final solution. Calculate the pH of the solution.
pH = 13.4 (approx.)
Consider the following equation for the formation of hydrogen fluoride from its elements at SATP:
H2 (g) + F2 (g) = 2 HF (g)
If the reaction begins with 1.00 mol / L concentrations of H2 (g) and F2 (g) and no HF (g), calculate the concentrations of H2 (g) and HF (g) at equilibrium if the equilibrium concertation of F2 (g) is measured to be 0.24 mol / L.
[ H2 (g) ] = o.24 mol / L
[ HF (g) ] = 1.52 mol / L
In a closed vessel at 500 °C, gaseous nitrogen, N2 (g), and hydrogen, H2 (g) , combine in an equilibrium reaction to form ammonia gas, NH3 (g) :
N2 (g) + 3 H2 (g) = 2NH3 (g)
The equilibrium concentrations of gaseous nitrogen, hydrogen, and ammonia, respectively, are 1.5 x 10 -5 mol/L, 3.45 x 10 -1 mol/L, and 2.00 x 10 -4 mol/L. Calculate the equilibrium constant, K, for this chemical reaction under these conditions.
K = 6.49 x 10-2
Define Hydrolysis
the reaction of the cation or anion of a salt with water to produce a change in the pH of the solution.
Define "first law of thermodynamics"
- total amount of energy in the universe is constant
- energy can be neither created nor destroyed
- can be transferred from one object or place to another
- or transformed from one form to another form of energy
calculate the standard Gibbs free energy change associated with each other of the following:
C2H3 (g) + H2 (g) = C2H6 (g)
G = - 100.302 KJ / mol
negative;
- spontaneous reaction
- goes right
- provides no information for rate of reaction
- 100.302 free energy
determine if percipate would form if the following equation is provided:
Ca(NO3)2 (aq) + (NH4)2SO4 (aq) = CaSO4 (aq) + NH4NO3 (aq)
Ksp = 7.1 x 10-5
Q = 6.0 x 10-3
Q > Ksp
precipitate forms
calculate the standard Gibbs free energy change associated with the following chemical process and interpret your result:
NH3 (g) + HCl(g) = NH4Cl(s)
G = - 91.25 KJ / mol
negative;
- spontaneous reaction
- no information provided
- moving right
- 91.25 KJ of free energy
The Kb for hydrazine, N2H4 (g) a rocket fuel is 1.7 x 10-6. What is the Ka of its conjugate acid.
Ka = 5.9 x 10-9
define "Arrhenius acids and bases theory"
- substance hat produce H+ or H3O+ when dissolved in water is called acid
- substance that produces OH- when dissolved in water is called called base
Nitrogen dioxide is in equilibrium with dinitrogen tetroxide. find the equilibrium concentration of nitrogen dioxide and dinitrogen tetroxide if the initial concentration of nitrogen dioxide is 0.650 mol/L
NO2 = 0.358 mol / L
N2O4 = 0.146 mol / L
Determine if precipitate if lead iodide froms if 100 mL of 2.1 x 10-3 mol/L of Pb(NO3)2 plus 50 mL of 0.0060 mol/L of NaI were mixed at SATP. Ksp of PbI2 = 8.5 x 10-9
Q =5.6 x 10-9
Ksp > Q
no precipitate is formed
Hydrogen iodide, HI(g), a compound used in the production of hydroiodic acid, HI (aq), is produced by reacting hydrogen gas and iodine vapour according to the following equation:
H2 (g) + I2 (g) = 2 HI (g)
The equilibrium constant, K for this reaction is 49.70 at 458⁰C. Calculate [HI (g) ] at equilibrium if the equilibrium concentration of the other two entities is 1.07 mol / L
[ HI(g) ] = 7.53 mol / L
CO2 (g) + 4 H2 (g) = CH4 (g) + 2 H2O(g)
predict 4 strategies, using le chatelier principle, to maximize the production of methane.
- increased pressure
- decreased temp.
- increased reactants
- remove products
define "the auto ionization of water"
The reaction between two water molecules producing a hydronium ion and a hydroxide
For each of the following mixtures, calculate a trial ions product, Q to predict whether a precipitate forms. All mixtures are made at SATP.
a. 50 mL of 0.040 mol / L Ca(NO3)2 (aq) plus 150 mL of 0.80 mol/ L (NH4)2SO4 (aq) .
b. 50 mL of 2.2 x 10-9 mol / L AgNO3 (aq) plus 50 mL of 0.050 mol / L NH4Cl (aq) .
c. 100 mL of 2.1 x 10-3 mol / L Pb(NO3)2 (aq) plus 50 mL of 0.0060 mol /L solution of NaI (aq) at SATP.
a) 6.0 x 10-4
b) 2.8 x 10-11
c) 8.5 x 10-9
A 0.15 mol / L solution of hydrochloric acid at SATP is found to have a hydrogen ion concentration of 0.15 mol / L. Calculate the concentration of the hydroxide ions.
[ OH - ] = 6.7 x 10-14 mol / L
Calculate the pH, pOH, and [ OH- (aq)] of a 0.042 mol / L HNO3 (aq) solution.
pH = 1.40
pOH = 12.60
[ OH - ] = 2.5 x 10-13 mol / L
What is the value of the base ionization constant, Kb for the acetate ion C2H3O2 - (aq) at SATP? The Ka value for acetate ion C2H3O2 - (aq) at SATP is 1.8 x 10-5
Kb = 5.6 x 10-10 mol / L