N
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR TEACHER USE
NZQA
Approved
Internal Assessment Resource
Chemistry Level 2
This resource supports assessment against:
Achievement Standard 91162 version 2
Carry out procedures to identify ions present in solution
Resource title: What’s the Solution?
3 credits
This resource:
Clarifies the requirements of the standard
Supports good assessment practice
Should be subjected to the school’s usual assessment quality assurance
process
Should be modified to make the context relevant to students in their school
environment and ensure that submitted evidence is authentic
Date version published by
Ministry of Education
February 2015 Version 2
Quality assurance status
These materials have been quality assured by NZQA.
To support internal assessment from 2015
NZQA Approved number: A-A-02-2015-91162-02-5419
Authenticity of evidence
Teachers must manage authenticity for any assessment from
a public source, because students may have access to the
assessment schedule or student exemplar material.
Using this assessment resource without modification may
mean that students’ work is not authentic. The teacher may
need to change figures, measurements or data sources or set
a different context or topic to be investigated or a different text
to read or perform.
This resource is copyright © Crown 2015
Page 1 of 9
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR TEACHER USE
Internal Assessment Resource
Achievement Standard Chemistry 91162: Carry out procedures
to identify ions present in solution
Resource reference: Chemistry 2.2B v2
Resource title: What’s the Solution?
Credits: 3
Teacher guidelines
The following guidelines are supplied to enable teachers to carry out valid and
consistent assessment using this internal assessment resource.
Teachers need to be very familiar with the outcome being assessed by Achievement
Standard Chemistry 91162. The achievement criteria and the explanatory notes
contain information, definitions, and requirements that are crucial when interpreting
the standard and assessing students against it.
Context/setting
This activity requires students to use given qualitative procedures to identify ions in
three unknown solutions.
Conditions
This assessment activity is designed to take place over 1–2 periods of in-class time.
Adjust these conditions to suit your students and context.
Resource requirements
red litmus paper
1 mol L-1 HCl (aq)
0.1 mol L-1 AgNO3 (aq)
0.1 mol L-1 BaCl2 (aq)
1 mol L-1 NH3 (aq)
1 mol L-1 NaOH (aq)
0.1 mol L-1 KSCN (aq)
1 mol L-1 H2SO4 (aq)
Unknown solutions:
– A: KI
– B: Fe(NO3)3
– C: FeSO4
– D: Zn(NO3)2
– E: Al2(SO4)3
safety goggles, test tubes, test tube racks, test tube brushes, droppers
This resource is copyright © Crown 2015
Page 2 of 9
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR TEACHER USE
Additional information
You should not use the activity exactly as it is (same ions in same order) since it is
available to all students and the assessment schedule includes examples of
appropriate responses. For example, you could substitute the ions given in this
activity with other appropriate ions (see EN 5).
The teacher could substitute the procedure chart given in the student resources for
an alternative flow chart/procedure that would enable students to identify the ions in
solutions.
You should carry out tests prior to the assessment to ensure that students will be
able to identify the ions with the solutions provided.
This resource is copyright © Crown 2015
Page 3 of 9
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR STUDENT USE
Internal Assessment Resource
Achievement Standard Chemistry 91162: Carry out procedures
to identify ions present in solution
Resource reference: Chemistry 2.2B v2
Resource title: What’s the Solution?
Credits: 3
Achievement
Achievement with Merit
Carry out procedures to
identify ions present in
solution.
Carry out procedures to
justify the identification of
ions present in solution.
Achievement with
Excellence
Carry out procedures to
comprehensively justify the
identification of ions present
in solution.
Student instructions
Introduction
This assessment activity requires you to use given qualitative procedures to identify
ions present in a number of solutions. You may carry out the qualitative procedures
collaboratively. However you will need to individually write a report to support the
identification of the ions in the solutions.
You will work in groups of 2–3 to carry out the practical qualitative analysis
procedures but your report must be written up individually.
Teacher note: Modify the group size or make this an individual task to suit your
context and students.
Your teacher will guide you about how much time you will have for this activity.
You will be assessed on how well you carry out these given procedures to identify
the ions in the solutions.
Task: Identifying Ions in Solutions
Identify the ions
In your groups, use the aqueous solutions and the procedures provided in Student
Resources A and B to identify the ions present in each of the following unknown
solutions.
Unknown Solution
Ion(s) to identify
A
anion
B
cation
C
D
cation
cation & anion
E
cation & anion
Record the steps you used to identify the ions and any observations you made during
the procedures. Use this primary data to identify the ion(s) in the solutions.
This resource is copyright © Crown 2015
Page 4 of 9
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR STUDENT USE
Report your findings
Write a report to support the identification of the ion(s) in each of the solutions.
For each ion identified:
identify the ion by name or formula
describe the steps you used to identify the ion
describe the observations you made during each procedure
identify by name or formula all precipitates formed
write balanced equations for the formation of all precipitates
write balanced equations for all complex ions formed
link your observations to any equations you write for the formation of precipitates
and/or complex ions.
This resource is copyright © Crown 2015
Page 5 of 9
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR STUDENT USE
Student Resource: Procedure Charts
A. Testing for anions: Cl-, CO32-, I-, NO3-, OH-, SO42Ion
Tests
Observations
Cl-
Add red litmus
does not change the colour
Add AgNO3(aq)
forms a white precipitate
Add NH3(aq)
precipitate dissolves
Add red litmus
turns red litmus blue
Add HCl(aq)
bubbles are produced
Add red litmus
does not change the colour
Add AgNO3(aq)
forms a yellow precipitate
Add NH3(aq)
precipitate remains
Add red litmus
does not change the colour
Add AgNO3(aq)
does not form a precipitate
Add BaCl2(aq)
does not form a precipitate
Add red litmus
turns red litmus blue
Add HCl(aq)
no bubbles are produced
Add red litmus
does not change the colour
Add AgNO3(aq)
does not form a precipitate
Add BaCl2(aq)
forms a white precipitate
CO32-
I-
NO3-
OH-
SO42-
This resource is copyright © Crown 2015
Page 6 of 9
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR STUDENT USE
B. Testing for cations: Ag+, Al3+, Ba2+, Cu2+, Fe2+, Fe3+, Mg2+, Pb2+, Na+, Zn2+
Ion
Tests
Observations
Ag+
Add 2 drops NaOH(aq)
forms a brown precipitate
Add 2 drops NH3(aq) to a new sample
forms a brown precipitate
Add excess NH3(aq)
precipitate dissolves
Add 2 drops NaOH(aq)
forms a white precipitate
Add excess NaOH(aq)
precipitate dissolves
Add 2 drops NH3(aq) to a new sample
forms a white precipitate
Add excess NH3(aq)
precipitate remains
Add H2SO4(aq) to a new sample
forms a colourless solution
Add 2 drops NaOH(aq)
forms a white precipitate
Add excess NaOH(aq)
precipitate remains
Add H2SO4(aq) to a new sample
forms a white precipitate
Add 2 drops NaOH(aq)
forms a blue precipitate
Add 2 drops NH3(aq) to a new sample
forms a blue precipitate
Add excess NH3(aq)
forms a deep blue solution
Fe2+
Add 2 drops NaOH(aq)
forms a green precipitate
Fe3+
Add 2 drops NaOH(aq)
forms an orange precipitate
Add 2 drops KSCN(aq) to a new
sample
forms a dark red solution
Add 2 drops NaOH(aq)
forms a white precipitate
Add excess NaOH(aq)
precipitate remains
Add H2SO4(aq) to a new sample
forms a colourless solution
Add 2 drops NaOH(aq)
forms a white precipitate
Add excess NaOH(aq)
precipitate dissolves
Add 2 drops NH3(aq) to a new sample
forms a white precipitate
Add excess NH3(aq)
precipitate remains
Add H2SO4(aq) to a new sample
forms a white precipitate
Na+
Add 2 drops NaOH(aq)
does not form a precipitate
Zn2+
Add 2 drops NaOH(aq)
forms a white precipitate
Add excess NaOH(aq)
precipitate dissolves in excess
Add 2 drops NH3(aq) to a new sample
forms a white precipitate
Add excess NH3(aq)
precipitate dissolves in excess
Al3+
Ba2+
Cu2+
Mg2+
Pb2+
This resource is copyright © Crown 2015
Page 7 of 9
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR TEACHER USE
Assessment schedule: Chemistry 91162 What’s the Solution?
Evidence/Judgements for Achievement
Evidence/Judgements for Achievement with
Merit
The student identifies the majority of ions (4),
including the majority of ions which form
precipitates (3/6), correctly.
The student identifies the majority of ions (4),
including the majority of ions which form
precipitates (3/6), correctly.
The student supports their identification of 4 ions
with experimental observations.
The student supports their identification of 4 ions
with experimental observations.
For each of the 4 ions, the student identifies by
name or formula all precipitates formed and
supports their responses with the evidence
required.
For each of the 4 ions, the student identifies by
name or formula all precipitates formed, justifies
their identification of the ions, writes balanced
equations for all of the reactions where
precipitates are formed, and links all precipitation
equations to the observations made during the
procedure.
For example:
The cation in Solution D is Zn2+
When 2 drops dilute of NaOH are added a white
precipitate forms. The precipitate is zinc hydroxide
/ Zn(OH)2.
When excess NaOH is added the precipitate
dissolves.
When 2 drops of NH3 is added a white precipitate
forms. The precipitate is zinc hydroxide / Zn(OH)2.
When excess NH3 is added the precipitate
dissolves.
The student supports their responses with the
evidence required.
The student identifies the majority of ions (6),
including the majority of ions which form
precipitates (3/6) and the majority of ions that form
complex ions (2), correctly.
The student supports their identification of 6 ions
with experimental observations.
For each of the 6 ions, the student identifies by
name or formula all precipitates formed,
comprehensively justifies their identification of the
ions, writes balanced equations for all of the
reactions where precipitates and complex ions are
formed, and links all precipitation and complex ion
equations to the observations made during the
procedure.
The student supports their responses with the
evidence required.
For example:
The cation in Solution D is Zn2+
When 2 drops dilute of NaOH are added a white
precipitate forms. The precipitate is zinc hydroxide
/ Zn(OH)2:
Zn2+(aq) + 2 OH
Evidence/Judgements for Achievement with
Excellence
(aq)
Zn(OH)2(s)
When excess NaOH is added the precipitate
dissolves.
When 2 drops of NH3 is added a white precipitate
forms. The precipitate is zinc hydroxide / Zn(OH)2:
For example:
The cation in Solution D is Zn2+
When 2 drops dilute of NaOH are added a white
precipitate forms. The precipitate is zinc hydroxide
/ Zn(OH)2:
Zn2+(aq) + 2 OH(aq) Zn(OH)2(s)
When excess NaOH is added the precipitate
dissolves:
Zn(OH)2(s) + 2 OH(aq) [Zn(OH)4]2(aq)
Zn2+(aq) + 2 OH(aq) Zn(OH)2(s)
When excess NH3 is added the precipitate
dissolves.
This resource is copyright © Crown 2015
or
Zn2+(aq) + 4 OH(aq) [Zn(OH)4]2(aq)
Page 8 of 9
Internal assessment resource Chemistry 2.2B v2 for Achievement Standard 91162
PAGE FOR TEACHER USE
When 2 drops of NH3 is added a white precipitate
forms. The precipitate is zinc hydroxide / Zn(OH)2:
Zn2+(aq) + 2 OH(aq) Zn(OH)2(s)
When excess NH3 is added the precipitate
dissolves:
Zn(OH)2(s) + 4 NH3(aq) [Zn(NH3)4]2+(aq) + 2 OH(aq)
or
Zn2+(aq) + 4 NH3(aq) [Zn(NH3)4]2+(aq)
Final grades will be decided using professional judgement based on a holistic examination of the evidence provided against the criteria in the
Achievement Standard.
This resource is copyright © Crown 2015
Page 9 of 9
0
