Area of Study 1 How do substances interact with water? In this area of study students focus on the properties of water and the reactions that take place in water including acid-base and redox reactions. Students relate the properties of water to the water molecule’s structure, polarity and bonding. They also explore the significance of water’s high specific heat capacity and latent heat of vaporisation for living systems and water supplies. Students investigate issues associated with the solubility of substances in water. Precipitation, acid-base and redox reactions that occur in water are explored and represented by the writing of balanced equations. Students compare acids with bases and learn to distinguish between acid strength and acid concentration. The pH scale is examined and students calculate the expected pH of strong acids and strong bases of known concentration.

On completion of this unit the student should be able to relate the properties of water to its structure and bonding, and explain the importance of the properties and reactions of water in selected contexts. To achieve this outcome the student will draw on key knowledge outlined in Area of Study 1 and the related key skills on pages 10 and 11 of the study design.

Properties of water

• trends in the melting and boiling points of Group 16 hydrides, with reference to the nature and relative strengths of their intermolecular forces and to account for the exceptional values for water

• specific heat capacity and latent heat including units and symbols, with reference to hydrogen bonding to account for the relatively high specific heat capacity of liquid water, and significance for organisms and water supplies of the relatively high latent heat of vaporisation of water.
Lesson 1 - Trends in MP of hydrides
Lesson 2 - hydrogen bonding
Lesson 3 - Heat capacity
Lesson 4 - Latent heat

Quiz 1 Solutions - trends in hydrides

Quiz 1a Solutions - Specific heat

Quiz 2 Solutions - latent heat

Quiz 3 Solutions - latent heat

Quiz 4 Solutions - latent heat

Quiz 5 Solutions - specific heat capacity, heat capacity.

Precipitation activity.

Quiz 1 Solutions (precipitates overall equations and ionic equations)

Quiz 2 Solutions ( overall equations and ionic equations)

Acid-base (proton transfer) reactions in water

• the Brønsted-Lowry theory of acids and bases including polyprotic acids and amphiprotic species, and writing of balanced ionic equations for their reactions with water including states
Lesson 1 - definitions of terminology used in acids and bases.
Lesson 2 - dilution

• the ionic product of water, the pH scale and the use of pH in the measurement and calculations of strengths of acids and bases and dilutions of solutions (calculations involving acidity constants are not required)

Lesson 3 (pdf) Lesson 3(doc)- Solutions
• the distinction between strong and weak acids and bases, and between concentrated and dilute acids and bases, including common examples

Lesson 4 - reactions with acids
lesson 4a- conjugates
Lesson 5 - ionic equations for acid reactions
Lesson 6 - pH
Lesson 7 Solutions - Strong/weak acids

• the reactions of acids with metals, carbonates and hydroxides including balanced full and ionic equations, with states indicated
• the causes and effects of a selected issue related to acid-base chemistry.

Redox (electron transfer) reactions in water

• oxidising and reducing agents, conjugate redox pairs and redox reactions including writing of balanced half and overall redox equations with states indicated
• the reactivity series of metals and metal displacement reactions including balanced redox equations with states indicated
• the causes and effects of a selected issue related to redox chemistry.

Lesson 1 - introduction to redox reactions.
Lesson 2 - Solution - half reactions, identifying oxidation and reduction reactions
Lesson 2a - Solution - half equations to balanced overall equation
Lesson 3 - the electrochemical series to predict spontaneous redox reactions and reactivity of metals.
Lesson 3a - metal displacement reactions
Lesson 4 Solutions - oxidation numbers
Lesson 5 - overall equations to half equations
Lesson 6 - from overall equation to galvanic cell design.
Lesson 7 - the electrochemical series as a tool.

Summary

Quiz 1 Solutions - introduction
Quiz 2 Solutions - writing balanced redox half equations and overall equations.
Quiz 3 Solutions- Identifying the oxidant and reductant using oxidation numbers and deriving oxidation and reduction half-equations.
Quiz 4 Solutions - drawing galvanic cells from an overall redox reaction
Quiz 5 Solutions- identifying redox reactions through oxidation numbers.
Quiz 6 Solutions - revision

Area of Study 2

How are substances in water measured and analysed?

In this area of study students focus on the use of analytical techniques, both in the laboratory and in the field, to measure the solubility and concentrations of solutes in water, and to analyse water samples for various solutes including chemical contaminants.

Students examine the origin and chemical nature of substances that may be present in a water supply, including contaminants, and outline sampling techniques used to assess water quality. They measure the solubility of substances in water, explore the relationship between solubility and temperature using solubility curves and learn to predict when a solute will dissolve or crystallise out of solution.

The concept of molarity is introduced and students measure concentrations of solutions using a variety of commonly used units. Students apply the principles of stoichiometry to gravimetric and volumetric analyses of aqueous solutions and water samples. Instrumental techniques include the use of colorimetry and/or UV-visible spectroscopy to estimate the concentrations of coloured species in solution, atomic absorption spectroscopy data to determine the concentration of metal ions in solution and high performance liquid chromatography data to calculate the concentration of organic compounds in solution.

Outcome 2 On completion of this unit the student should be able to measure amounts of dissolved substances in water and analyse water samples for salts, organic compounds and acids and bases. To achieve this outcome the student will draw on key knowledge outlined in Area of Study 2 and the related key skills on pages 10 and 11 of the study design.

Key knowledge
Water sample analysis

• existence of water in all three states at Earth’s surface including the distribution and proportion of available drinking water
• sampling protocols including equipment and sterile techniques for the analysis of water quality at various depths and locations
• the definition of a chemical contaminant and an example relevant to a selected water supply.

Measurement of solubility and concentration
• the use of solubility tables and experimental measurement of solubility in gram per 100 g of water
• the quantitative relationship between temperature and solubility of a given solid, liquid or gas in water
• the use of solubility curves as a quantitative and predictive tool in selected biological, domestic or industrial contexts
• the concept of solution concentration measured with reference to moles (mol L^-1) or with reference to mass or volume (g L^-1, mg L^-1 , %(m/m), %(m/v), %(v/v), ppm, ppb) in selected domestic, environmental, commercial or industrial applications, including unit conversions.
Lesson 1 Solubility
Lesson 2 Solubility curves
Lesson 3 Solutions Constructing a solubility curve
Lesson 3-4 Unit conversion and concentration.
-ppm
-(v/v)%
-(w/v)%
-(w/w)%

Lesson 5-6 Molarity

Solubility curve of KNO₃ Solutions practical investigation.

Quiz 1 Solutions concentrations %w/w,%w/v, %v/v, molarity, ppm.
Quiz 2a Solutions concentrations of ions

Quiz 2b Solutions calculating amount of solute

Concentration (ppm, %v/v, %w//v, %w/w) revision sheet solution

Quiz 3

Quiz 4 Solutions -more precipitation reactions overall and ionic equation

Revision 1 Solutions

Analysis for salts in water
• sources of salts found in water (may include minerals, heavy metals, organo-metallic substances) and the use of electrical conductivity to determine the salinity of water samples
• the application of mass-mass stoichiometry to gravimetric analysis to determine the mass of a salt in a water sample
Practical- Determination of Sulphate content in fertiliser

Gravimetric analysis

Sulphate content in fertiliser

Selection of Friday quizzes. The teacher can decide when to use these quizzes to gauge student progress.
Quiz 1 Solution

Quiz 2 Solution

Quiz 3 Solution

Quiz 4 Solution

Quiz 5 Solution

Quiz 6 Solution

Revision for gravimetric analysis (1) Solution
Revision for gravimetric analysis (2) Solution
Revision for gravimetric analysis (3) Solution

Gravimetric analysis from past exams.
2014 VCE
2013 VCE
2012 VCE
2011 VCE
2010 VCE
2010 HSC
2009 VCE
2008 VCE
2007 VCE
2007 NSW
2006 VCE
2005 VCE

UV-visible

Quiz 1 Solution
Quiz 2 Solution
Quiz 3 Solution
Quiz 4 Solution
Quiz 5 Solution

Atomic absorption

Quiz 1 Solution

Quiz 2 Solution

Atomic emission

Analysis for organic compounds in water
• sources of organic contaminants found in water (may include dioxins, insecticides, pesticides, oil spills)
• the application of high performance liquid chromatography (HPLC) including the use of a calibration curve and retention time to determine the concentration of a soluble organic compound in a water sample (excluding details of instrument).

Analysis for acids and bases in water
• sources of acids and bases found in water (may include dissolved carbon dioxide, mining activity and industrial wastes)
• volume-volume stoichiometry (solutions only) and application of volumetric analysis including the use of indicators, calculations related to preparation of standard solutions, dilution of solutions and use of acid-base titrations to determine the concentration of an acid or a base in a water sample.

Lesson 1 Solutions vol -vol stoichiometry -introduction to volumetric analysis
lesson 1 (word doc)
Lesson 2 - Titration and the glassware
Lesson 3 - indicators,equivalence point, end point and pH curves
Lesson 3a Solution- indicators
Lesson 3b Solution - dilution and titration
Lesson 3c Solution - dilution and titration
Lesson 3d Solution - dilution, titration and indicators
Lesson 4 Solution - dilution and titration
Lesson 5 Solution - dilution and titration
Lesson 6 - standard solutions, primary standard
Lesson 6a Solution - standard solution and titration
Lesson 7 Solution - errors and indicators in titration

Lesson 8 - virtual analysis of acetylsalicylic acid in an aspirin tablet.

Volumetric analysis summary sheet.

Quiz 1 Solution - pH

Quiz 2 Solution - excess calculation and pH

Quiz 3 Solution

Quiz 4 Solution

Quiz 5 Solution

Quiz 6 Solution

Quiz 7 Solution

Outcome 3

On completion of this unit the student should be able to design and undertake a quantitative laboratory investigation related to water quality, and draw conclusions based on evidence from collected data. To achieve this outcome the student will draw on key knowledge outlined in Area of Study 3 and the related key science skills on pages 10 and 11 of the study design.

Key knowledge
• the chemical concepts specific to the investigation and their significance, including definitions of key terms, and chemical representations
• the characteristics of laboratory techniques of primary qualitative and quantitative data collection relevant to the investigation: sampling protocols; gravimetric analysis, acid-base titrations and/or pH measurement; precision, accuracy, reliability and validity of data; and minimisation of experimental bias
• ethics of and concerns with research including identification and application of relevant health and safety guidelines
• methods of organising, analysing and evaluating primary data to identify patterns and relationships including identification of sources of error and uncertainty, and of limitations of data and methodologies
• observations and experiments that are consistent with, or challenge, current chemical models or theories
• the nature of evidence that supports or refutes a hypothesis, model or theory
• options, strategies or solutions to issues related to water quality
• the key findings of the selected investigation and their relationship to solubility, concentration, acid/base and/ or redox concepts
• the conventions of scientific report writing including chemical terminology and representations, symbols, chemical equations, formulas, units of measurement, significant figures and standard abbreviations.

Assessment

The award of satisfactory completion for a unit is based on a decision that the student has demonstrated the set of outcomes specified for the unit. Teachers should use a variety of learning activities and assessment tasks that provide a range of opportunities for students to demonstrate the key knowledge and key skills in the outcomes.

The areas of study, including the key knowledge and key skills listed for the outcomes, should be used for course design and the development of learning activities and assessment tasks. Assessment must be a part of the regular teaching and learning program and should be completed mainly in class and within a limited timeframe.

Revision Unit 2 2012

Solutions