chemical testing for ions

Chemical testing for Ions

OCR SCIENCE – UNIT 1 BEST PRACTICE

Prior learningChemicals can react together and change colourKey wordsReact, precipitate, colour change, identify, Cations, Anions

I am learning to: identify cations and anions in different solutions by their colour change

I will be successful if I can:• Describe the term cation and anion and explain the test to be carried out• Carry out a practical activity safely (having completed a risk assessment)

to confirm the presence of different cations an anions• Complete a table to show results of practical tests• Conclude, Evaluate and comment on reliability of the test

Outcome: I can identify unknown ions in a given solution.

TO ACHIEVE A MERIT: 1. Add DETAIL to your report by explaining what is happening in each step

using the guidance sheets.2. Relate the results of the test back to the scenario of students becoming

ill having played on the playing fields.3. Complete an aim, prediction and method in handwritten form to add to

your testing notes.

Any of these can be completed at home or with Ms C’s help at break, lunch or after school.


Introduction: what are ions?

I am learning to:identify cations and anions in different solutions by their colour change

• Ions are charged particles.

• Positively charged particles are called CATIONS (because they are attracted to the negative electrode called the cathode which are usually metals)

• Negative Ions are called ANIONS because they are attracted to the anode these are usually non-metals

ReferenceI am learning to:identify cations and anions in different

solutions by their colour change

Ion Test Result

Chloride Add Silver nitrate Solution White precipitate

Sulphate Add acidified Barium chloride solution

White precipitate

Carbonate Add dilute acid and test gas with limewater

Milky white precipitate

Copper (Cu++) Add Sodium hydroxide solution Blue precipitate

Iron Add Sodium hydroxide solution Brown precipitate



Copper Cations

Iron Cations

Sodium hydroxide



Carbonate Anions

Chloride Anions

Silver Nitrate

Acid



Sulphate Anions

Barium Chloride

Risk AssessmentI am learning to:identify cations and anions in different


x

What is the overall level of risk? (Tick appropriate box – if risk is high further steps must be taken to minimum the risk of the procedure)

Department: Science Room Number: R4Brief summary of activity: Chemical tests for chlorides, sulphates and carbonatesList hazardous procedures and the hazards) relating to them

ProcedureUsing squirt bottles & glass

HazardChemical in eye, broken glass cuts

List the substances hazardous to health and the hazards) relating to them

Substance chemicals

HazardIrritant, harmful and corrosive

Risk and Safety phrases Wear gogglesList who might be exposed to the hazard substance(s).

(e.g. staff, students, visitors, cleaners)Staff & pupils

Assessing the level of risk How severe is any injury or health effect likely to be? MediumHow likely is exposure to the hazard? Medium

High Medium Low

Emergency Procedures (first aid actions, fire actions, spill action)Wash hands under cold waterWipe up any spillsBrush up broken glass and put in glass bin

Disposal requirements Technician to dispose of waste in prep roomDate: Name: Signature:

ResultsI am learning to:identify cations and anions in different


Test Samples

Add Silver nitrate solution

Add acidified Barium chloride solution

Add dilute acid and bubble gas through limewater

Add Sodium hydroxide

Sample ion

A B Soil C Water

ResultsI am learning to:identify cations and anions in different


Test Samples

1 2 3 water soil

Add Silver nitrate solution yes X X Yes X

Add acidified Barium chloride solution

X Yes X X X

Add dilute acid and bubble gas through limewater

X X X X X

Add Sodium hydroxide x X yes X yes

Sample ion chloride sulphate copper chloride Iron

Conclusion of findings• Conclusion of findings:

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


Reliability1. Do qualitative tests tell you how much of a substance is present?No, just if the substance is presentNo, just if the substance is present2. If the test substance is a mixture will one get clear results?No more than one result may showNo more than one result may show3. Will the tests work if the substance is insoluble?nono4. Is there an amount of substance needed to get a positive test?Small amounts of each substance should workSmall amounts of each substance should work5. Can your test substances be contaminated?Yes if clean pipettes are not usedYes if clean pipettes are not used


HOMEWORK

Complete the associated worksheet on Chemical tests

Approx. 10mins

I am learning to: view samples using a microscope and test samples for metals using flame tests

I am learning to: identify cations and anions in different solutions by their colour change

I will be successful if I can:• Describe the term cation and anion• Carry out a practical activity safely to confirm the

presence of different cations an anions• Complete a table to show results of practical tests

Outcome: I can identify unknown ions in a given solution.


Summary – draw the colour changes of each test on plain paper


Copper Cations

Iron Cations

Sodium hydroxide

chemical testing for ions

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