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Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable What is a hypothesis? “The higher/greater the concentration of sodium hydroxide solution the greater/bigger/higher the volume of acid needed to neutralise it” Repeat ISA – Research notes
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What research sources did you use?
Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable What research sources did you use? 1. 2. AQA Science Chemistry text book Pages ISBN: Look at the following 2sources – do you think they are any good?? Repeat ISA – Research notes
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Equipment list: Clamp and Clamp stand – to hold the burette
Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable Equipment list: Clamp and Clamp stand – to hold the burette Burette – to accurately measure the volume of the unknown acid Pipette – to accurately measure 25cm3 of each concentration of sodium hydroxide Pipette filler – to fill the pipette Beaker Conical flask – for the reaction White tile – to see the colour change clearly Indicator – to show the colour change when neutralisation has happened Funnel – to fill the burette Acid – hydrochloric acid (0.5M) Alkali (sodium hydroxide, 25cm3, 0.25M, 0.5M, 0.75M, 1.0M, 1.25M) Repeat ISA – research notes
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Add a few drops of the indicator and swirl gently
Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable Method: Collect all of the equipment and set it up, making sure the burette is secure and straight in the clamp stand (make sure it has been rinsed with distilled water and then the acid) Using a funnel, fill the burette up to the 0cm3 mark, then remove the funnel so no extra drops fall in afterwards Pour some of the alkali into a beaker and using the pipette and pipette filler, fill the pipette to 25cm3, making sure the meniscus falls exactly on the 25cm3 line Empty the alkali into the conical flask and place this on the white tile under the burette Add a few drops of the indicator and swirl gently For the rough titration, add the acid from the burette slowly and when you start to see a change of colour slow the burette right down. Stop when you see the change of colour Repeat the experiment, but this time when you get near to the value from your rough titration, slow the burette down so that the acid is being added dropwise… Repeat ISA – research notes
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What are the variables? Independent variable
Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable What are the variables? Independent variable Concentration of sodium hydroxide (alkali) Dependent variable Volume of hydrochloric acid needed to neutralise the alkali Control variables Concentration of acid, volume of sodium hydroxide, person doing the titration (swirling), person filling the pipette, indicator Repeat ISA – research notes
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Risk assessment: Hazard Risk How to minimise it? Key Words:
Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable Risk assessment: Hazard Risk How to minimise it? Glassware could smash Low Work in the middle of the desk, not near the edge Acid or alkali could burn skin/eyes Wear goggles at all times. Handle chemicals carefully. Work in the middle of the desk not near the edge Indicator could be toxic Handle carefully. Wash hands after practical Repeat ISA – research notes
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On a blank sheet of lined paper, draw this results table
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Do you results support the hypothesis?
Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable Do you results support the hypothesis? Yes they do The higher/stronger the concentration of the alkali the higher/larger/bigger the volume of acid needed to neutralise it Repeat ISA –
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What was the resolution?
Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable What was the resolution? 0.05cm3 This was appropriate because it gave very accurate results Results showed clear pattern Pattern would be easy to see even if results were very close to each other Repeat ISA –
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What was the independent variable?
Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable What was the independent variable? Concentration of sodium hydroxide/alkali 0.25M – 1.5M It was suitable because it gave a clear pattern/trend of results which clear supported the hypothesis Repeat ISA –
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Did you have to repeat any results?
Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable Did you have to repeat any results? No All results followed a pattern No anomalous results Are all close to the line of best fit on your graph Repeat ISA –
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Key Words: Dependent variable Independent variable Titration Accurate
Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable Dependent variable Independent variable Repeat ISA –
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Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable The case studies 1: this used a different alkali but it did support the hypothesis and showed the same pattern 2: shows the same trend, so technically does support the hypothesis. Shows it a different way – measures the pH at different intervals rather than volume of acid from burette 3: It does show the same trend and supports the hypothesis but is not very reliable because they only did 2 trials, so is very hard to see if any of the results are anomalous or not Repeat ISA –
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Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable So… What’s the context?? Titrations are used in the food industry. It is used to quality check the acidity of vinegar to check it has the right pH. They can test the volume of alkali needed to neutralise the acid (in the vinegar) to check that the concentration and pH are right and safe Repeat ISA – research notes
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Key Words: Titration Accurate Titre Burette Pipette Neutralisation Acid Alkali Volume Beaker Conical flask Indicator Swirl End point Variable Why compare results? Check your results with others and see if the patterns/trends are similar This lets you see if the investigation is reproducible If everything in the investigation is the same and the other results follow the same pattern/trend it is a reproducible investigation Repeat ISA – research notes
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