Lewis Structures
Titrations & Buffers
Titrations & Buffers 2.0
Lewis Structures 2.0
Mix
100
What is the most important principle in determining the geometry between electron pairs?
Minimizing the relative repulsion
100
Buffers are a solution that _____ change in pH when limited amounts of an ______ or a _____ are added to it.
Resists, acid, base
100
What are the two factors that the effectiveness of a buffer depends on?
- the relative amounts of acid or base
- the absolute concentrations of acid or base
100
Define the VSEPR theory.
Used to predict the molecular geometries of compounds based on the number of electron groups attached to the central atom of the molecule.
100
Give the lewis structure for C2H4 and determine the electron geometry.
C1 - Trigonal Planar
C2 - Trigonal Planar
200
Write the lewis structure for CCl4?
200
Which of these combinations produce a buffer solution?
- HCl and NaCl
- HNO2 and NaNO2
- NH4NO3 and HNO3
- No
- Yes
- No
200
An effective buffer should be able to _____ ______ amounts of added acid or base.
An ______ is a weak organic ______ that changes color depending on the pH.
neutralize moderate
indicator acid
200
What is the bond angle for the molecular geometry of Seesaw?
<120º (equatorial)
<90º (axial)
200
A 150.0 mL sample of 0.250 M sodium hydroxide is titrated with 0.300 M hydrochloric acid. Calculate the pH after the addition of 80.0 mL of acid
pH = 12.77
300
Determine the electron pair geometry of SO2?
Linear
300
Given a buffer solution with 250.0 mL of 0.345 M HCN and 350.0 mL of 0.130 M NaCN, what is the pH.
Ka = 4.3 x 10-5
pH = 4.09
300
Given a pH of 3.75, 50 mL of 0.254 M of HCN, and 80 mL of 0.105 M of NaCN, what is HCN Ka?
Ka = 1.17 x 10-4
300
Determine the molecular geometry of SeO3-2?
Trigonal pyramidal
300
A 100.0 mL sample of 0.35 M C2H5NH2 is titrated with 0.30 M HNO3. Determine the pH solution at one-half the equivalence point. Kb = 3.40 x 10-5
pH = 9.53
400
Determine the electron geometry and the molecular geometry for SeOF2?
Eg: tetrahedral
Mg: Trigonal pyramidal
400
A 2.0L buffer solution contains 0.350 mol of HClO and 0.200 mol of NaClO. The pKa value is 5.64. What is the new pH after adding 0.050 mol of NaOH to the buffer?
pH = 5.56
400
An 870.0 mL sample of 0.36 M HF is titrated with NaOH. Determine the pH of the solution before the addition of 2.8 L of KOH. Ka = 3.9 x 10-5
2.43
400
Determine the lewis structure of CO3-2. Does this molecule exhibit resonance, if so draw it?
Yes this molecule has a resonance structure.
400
A 1.5L sample of 0.35 M HCHO2 is titrated with 0.24 M KOH. Determine the pH of the solution after the addition of 43.0 mL of KOH. The Ka = 2.6 x 10-4
pH = 1.86
500
Give the lewis structure for H2SO3?
500
A 50.0 mL sample of 0.150 M hydrochloric acid is titrated with 0.200 M sodium hydroxide. Calculate the pH after the addition of 40.0 mL of base.
pH = 11.74
500
Calculate the pH of a buffer solution that is formed by mixing 270.0 mL of 0.54 M in NH3 with 130.0 mL of 0.32 M in NH4Cl. For ammonia, Kb = 3.5 x 10-4
pH = 11.08
500
Determine the molecular geometry around each central atom for C2H5OH?
C1 - Tetrahedral
C2 - Tetrahedral
O1 - Bent
500
An 380.0 mL sample of 0.45 M NH3 is titrated with HBr. Determine the pH of the solution before the addition of 1.5 L of HCl. Ka = 2.3 x 10-5
pH = 11.51