Researching Chemistry Flashcards
Complete a levelled diagram to show an apparatus suitable for the production of gas.
Gas syringe (apparatus)
Suggest why carbon dioxide can be collected over water.
Carbon Dioxide is insoluble
The first step was to accurately measure a a mass of 1.5g of the mixture into a crucible, using a balance. Describe fully how the student could carry out this step.
Weigh the mixture and crucible, weight the empty crucible then calculate the difference in mass.
Suggest why the student had to lift the lid from time to time when heating a mixture of MgCO3
To allow carbon dioxide to escape
Explain why a Bunsen burner is a suitable method of heating a reaction.
Reactants are not flammable
In some parts of the country, tap water contains a higher level of dissolved metal salts. State the term used to describe the is water.
Deionised water
Suggest a reason why the soft drink needed to be flat before the density was determined.
The dissolved gas will affect the density.
Describe fully a method that the student could have used to accurately measure the mass 10.0cm^3 of each sucrose solution.
Use a pipette to measure the sucrose solutions. Weigh by difference.
Draw a diagram of a volumetric flask.
Refer to jotter **
Suggest why the experiment was carried out in a polystyrene cup with a lid.
Polystyrene is a good insulator.
Suggest why a wet paper towel is wrapped around the test tube.
To act as a condenser
Describe in detail how a burette should be prepared and set up, ready to begin the titration.
Rinse the burette with the solution, take reading from the bottom of the meniscus, remove filter funnel.
Explain fully why the flask was left for 24 hours, without a stopper.
So that it can fully react.
Explain why the student should use deionised water or distilled water, rather than tap water, when preparing the stock solution.
Metal ions are present
Name the piece of apparatus which should be used to transfer 10cm^3 of stock solution to a standard flask.
Pipette
Given an accurately known mass of oxalic acid, describe fully how 250cm^3 of a standard solution of oxalic acid could be prepared.
Dissolve oxalic acid in small volume of water. Transfer quantitatively with the rinsing. Fill it up to the the line in a volumetric flask.
Draw a diagram of a pipette suitable for measuring an accurate volume.
Refer to jotter **
State the term used to describe titre volumes within 0.2 cm^3 of each other.
Concordant
State what is meant by a standard solution.
A solution of accurately known concentration
Describe how a pipette should be prepared and used to accurately measure the sample of seawater.
Rinse with sea water and fill it to the mark, read from the bottom of the meniscus.
State why an indicator is used.
To show when the endpoint is reached
Suggest an improvement to the apparatus that would prevent heat loss to the surroundings.
Draft Shields and Metal Beaker
Suggest why a water bath is used to heat the reaction.
The reactant this flammable
Describe the steps involved in measuring the mass of the seaweed by difference.
Measuring the mass of the container and seaweed then subtracting the mass of the container.
Suggest why the beaker should be dry.
To keep the concentration of the reactants constant.
Describe how to transfer quantitatively.
Rinse the beaker and transfer the rinsings to the flask
Suggest why the titration must be carried out under acidic conditions.
To provide H+ ions for the reaction.
Suggest why it is not necessary to add an indicator to this titration.
The reaction is self indication (colourless)
Suggest a reason why there is a small test tube filled with cold water in the neck of the tube containing the reaction mixture.
To condense the reactants or products so that gases don’t escape.
Describe the procedure which should be used to prepare 100cm^3 of 20% ethanol solution.
Use a pipette to measure the 20cm^3 of ethanol. Fill up to the mark of the volumetric flask.
Explain why the aluminium foil needs to be heated at the start of the preparation despite the reaction being highly exothermic.
To supply activation energy.
