3.1.2.2 Moles In Solution
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What is the unit for volume ?
dm^3
Define solution
When a solute is dissolved in a solvent
Define solute
A substance that has dissolved in a solvent to make a solution and it can be a gas liquid or solid
Define solvent
The liquid that has dissolved the solute to make a solution
Definite concentration
Tells you the amount of solute dissolved in a known volume of solvent Unit is mol dm^-3 Alternative unit is a measure of the mass of solute dissolved in a given volume of solvent g dm^-3
What’s the concentration calculation
Conc=mol/vol
What do volumes have to be converted to before being using in equation?
Volumes must be converted into dm^3 before being used in equation
If a concentration is in mol dm^-3 how is it converted to g dm^-3
Conc in mol dm-3 x Mr = conc in g dm^-3
Equation for percentage uncertainty
Error /reading x100
How do you reduce percentage uncertainty
Increase the reading
What are titrations ?
Methods of finding the conc of a solution by a reacting it with an alkali in the presence of an indicator
What’s a standard solution?
Means it’s exact conc is known and so if a precise volume of this solution is measured out the number of moles can be calculated
Steps for titration
Fill a burette with an acid of known concentration Accurately measure out 25cm^-3 of the alkali standard solution using a pipette and transfer to a conical flask Add a few drops of suitable indicator to the alkali Slowly add the acid from the bureau into the conical flask swelling constantly as soon as the indicated changes colour the solution has turned neutral so stop adding the acid record the volume of acid which has been added Repeat the process until you get your results which are within 0.1 cm³ of each other the meaning of the two results are then use the calculate the average titre
Define titre
Volume you get from the burette
What can an average titrebe used to determine
Calculate the unknown concentration