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level: Titrations

Questions and Answers List

level questions: Titrations

QuestionAnswer
What are Titrations used for?-This is used to find out how much Acid, or Alkali is needed to Neutralise the Other.
Explain how to use an Titration-First, measure out the Set Volume of Alkali [Or acid, depends what you are Finding out] and then add a few drops of an Indicator [Phenolphthalein, Pink or Methyl Orange, Orange] -Then, fill the Burette with a Standard Solution of the Acid -As you are then adding the Acid to the Alkali, keep Swirling and also make sure you go Slow -When the Indicator changes, all the Alkali has been Neutralised [Phenolphthalein will be Colourless, Methyl Orange will be Red] -Record the Volume of Acid used, this is called the Titrate, and repeat the Process to get an Average, so that it makes it more Reliable
Why is Universal Indicator bad for Titrations?-This is because its a Gradual Change, and its very hard to see when its exactly Neutral, compared to the Others, which is Instant
What is a Rough Titration? Why is it Important?-Before you try and find out the Precise Result, you need to find the General Area of where the Neutralising will happen, so then the Next Time around, you can go Slow and more Precise there
How can the Titration Results be used to find the Concentration out?-Since you already know the Concentration of one of the 2 Reactants, and the Volume of both of the Reactants, simply find out how many Moles you have, Ratio the Equation with the number of Moles, and find out the Concentration
What is the Formula of finding out Concentration [Moles]Concentration [Mol/dm₃] = Number of Moles / Volume [dm₃]
If it takes 25cm₃ of 0.100 Mol/dm₃ of Sulfuric Acid to Neutralise 30cm₃ of Sodium Hydroxide, and the Equation is: 2NaOH + H₂SO₄ --> Na₂SO₄ + 2H₂O -What's the Concentration of the Alkali in mol/dm₃-First find out how many Moles of the Acid you have-- Moles = Concentration x Volume --> Moles = 0.1 x (25/1000) =0.0025 Moles of H₂SO₄ -Now, using the Balanced Equation, Ratio the Moles -1 Moles reacts with 2 Moles of NaOH, so 0.0025 Moles reacts with 0.0050 Moles of NaOH -Now using that Answer, find out the Concentration: Conc = N of Moles / Vol --> Conc = 0.0050 / (30/1000) =0.167 mol/dm₃
How can you Convert the Concentration into g/dm₃ from mol/dm₃ and Vice Versa?-Concentration [mol/dm₃] = Concentration [g/dm₃] / Relative Formula Mass -Concentration [g/dm₃] = Concentration [mol/dm₃] x Relative Formula Mass