Personal Response Systems Alex Norquist Department of Chemistry Haverford College

ConcepTests  Eric Mazur developed ConcepTests for use in introductory level physics courses at Harvard  interactive questions  small group discussions  3 – 5 questions per class  Responses are provided by volunteers  Class wide evaluation is difficult

Clickers  Advantages of clickers  anonymous responses  forced wait time  increased class participation  true formative assessment  Two main uses of clickers  pre-conceived ideas / misconceptions  key ideas

Key ideas  A conceptual question is asked at the beginning of a topic to probe the understanding of students  correct / incorrect answers are usually not discussed  early questions are often revisited after discussion the relevant material  Gateway questions are asked during lectures to probe understanding of specific concepts  the class response dictates what I do next  strong consensus on the correct response results in a short explanation  a weak consensus (or worse) results in a review of the material  true formative assessment  Questions containing several parts are asked at the end of the discussion of a topic  multiple concepts are incorporated into these multipart questions  these questions are often designed to show how different concepts are interrelated

Disorder  Put these arrays in order 1) 1, 2, 3, 4 2) 2, 3, 4, 1 3) 1, 4, 3, 2 4) 2, 1, 4,

Disorder  Put these arrays in order 1) 1, 2, 3, 4 2) 2, 3, 4, 1 3) 1, 4, 3, 2 4) 2, 1, 4,

Disorder  Put these arrays in order 1) 1, 2, 3, 4 2) 2, 3, 4, 1 3) 1, 4, 3, 2 4) 2, 1, 4,

Clicker question  Predict whether there is an increase or decrease in entropy for the following reaction SO 2(g) + Cl 2(g) + 2H 2 O (l) → H 2 SO 4(aq) + 2HCl (aq) 1) increase2) decrease

Clicker question  Calculate the  S r o for the reaction, given the following parameters: S r o for SO 2(g) J/K mol; Cl 2(g) J/K mol; 2H 2 O (l) J/K mol; H 2 SO 4(aq) 20.1 J/K mol; 2HCl (aq) 56.5 J/K mol SO 2(g) + Cl 2(g) + 2H 2 O (l) → H 2 SO 4(aq) + 2HCl (aq) 1) 400 J / K mol 2) -400 J / K mol 3) -406 J / K mol 4) 406 J / K mol

Clicker question  Calculate the  S surr for the reaction at 298 K, given the following parameters:  H f for SO 2(g) kJ/mol; Cl 2(g) 0 kJ/mol; 2H 2 O (l) kJ/mol; H 2 SO 4(aq) kJ/mol; 2HCl (aq) kJ/mol. SO 2(g) + Cl 2(g) + 2H 2 O (l) → H 2 SO 4(aq) + 2HCl (aq) 1) 1259 J / K mol 2) J / K mol 3) J / K mol 4) 3649 J / K mol

Clicker question  Is this reaction spontaneous at 298 K? SO 2(g) + Cl 2(g) + 2H 2 O (l) → H 2 SO 4(aq) + 2HCl (aq) 1) yes2) no

Clicker question  Is this reaction spontaneous at 298 K? SO 2(g) + Cl 2(g) + 2H 2 O (l) → H 2 SO 4(aq) + 2HCl (aq) 1) yes2) no  S total =  S system +  S surr  S total = J / K mol  S total = 859 J / K mol

Multipart question  The perchlorate ion, ClO 4 -, is described by resonance structures. Which is the most plausible based upon formal charges?

Multipart question  The average length of a single Cl – O bond is 172 pm and that of a double bond is 140 pm. The Cl – O bond length in the perchlorate ion is found experimentally to be 144 pm for all four bonds. Identify the most plausible Lewis structure based upon these data.

2.103  Considering the oxidation number of chlorine in the perchlorate ion, identify the most plausible Lewis structure, assuming that lone pairs belong to the atom to which they are attached but that all electron shared in a bond belong to the atom with the highest electronegativity. Are the three approaches consistent? Why?

2.103  Considering the oxidation number of chlorine in the perchlorate ion, identify the most plausible Lewis structure, assuming that lone pairs belong to the atom to which they are attached but that all electron shared in a bond belong to the atom with the highest electronegativity. Are the three approaches consistent? Why?