NZQA registered unit standard
8949 version 4
Page 1 of 3
Title
Characterise the composition of acid and base solutions
Level
3
Credits
4
Purpose
People credited with this unit standard are able to determine
the chemical species present in acid and base solutions, and
characterise acid-base titration curves.
Classification
Science > Chemistry
Available grade
Achieved
Explanatory notes
Examples are restricted to monoprotic acids and their salts.
Outcomes and evidence requirements
Outcome 1
Determine the chemical species present in acid and base solutions.
Evidence requirements
1.1
Experimental evidence is used to qualitatively determine the relative
concentration of species present in aqueous solutions of acids, alkalis, and
salts.
Range
experimental evidence includes - conductivity, pH, solubility.
1.2
Ka or pKa values are used to calculate the pH of weak acid and weak alkaline
solutions.
1.3
The pH of weak acid and weak alkaline solutions are used to calculate the Ka or
pKa values.
Outcome 2
Characterise acid-base titration curves.
Range
weak acid /strong base, strong acid /weak base, strong acid/strong base;
evidence of one is required.
NZQA National Qualifications Services
SSB Code 130301
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
8949 version 4
Page 2 of 3
Evidence requirements
2.1
The pH of key points of acid-base titration curves is predicted.
Range
2.2
any two of - initial pH, equivalence point, buffer region.
Indicators which will change colour at the equivalence point are selected for an
acid-base titration.
Replacement information
This unit standard and unit standard 8950 replaced unit
standard 6346.
Planned review date
31 December 2017
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
1 November 1996
31 December 2013
Revision
2
7 July 1999
31 December 2013
Revision
3
12 February 2003
31 December 2013
Review
4
20 September 2012
N/A
Consent and Moderation Requirements (CMR) reference
0226
This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA,
before they can report credits from assessment against unit standards or deliver courses
of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and
which are assessing against unit standards must engage with the moderation system that
applies to those standards.
Requirements for consent to assess and an outline of the moderation system that applies
to this standard are outlined in the Consent and Moderation Requirements (CMR). The
CMR also includes useful information about special requirements for organisations wishing
to develop education and training programmes, such as minimum qualifications for tutors
and assessors, and special resource requirements.
NZQA National Qualifications Services
SSB Code 130301
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
8949 version 4
Page 3 of 3
Comments on this unit standard
Please contact NZQA National Qualifications Services nqs@nzqa.govt.nz if you wish to
suggest changes to the content of this unit standard.
NZQA National Qualifications Services
SSB Code 130301
 New Zealand Qualifications Authority 2016