C4 Flashcards
What is Avogadro’s constant?
6.02*10(^23)- the number of atoms in a mole
What do Ar and Mr mean?
Relative atomic mass and relative formula mass
Why may percentage yield differ from the theoretical yield?
-The reaction may be reversible
-Unwanted products may be formed
-Reactants may not be as pure
-Some of a desired product may be lost during separation from the mixture
What is atom economy?
A measure of the quantity of reactants that end up as useful products
Why is it important to maximise atom economy?
-To conserve resources and save energy/expenses
-In order to minimise pollution from potentially harmful products
How many centimetres are in a decimetre?
10cm=1dm
Describe how you would carry out a titration:
-Use the pipette and pipette filler to add a measured volume of alkaline solution to a clean conical flask
-Add a few drops of indicator and put the conical flask on a white tile
-Fill the burette with an acid and note the starting volume
-Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix
-Stop adding the acid when the end-point is reached (when the indicator first permanently changes colour) Note the final volume reading
-Repeat steps 1 to 5 until concordant titres are obtained
-More accurate results are obtained if acid is added drop by drop near to the end-point
What is the molar gas volume? (The volume of gas at room temperature/pressure)
24dm(^3) per mole
What colour is methyl orange in neutral and alkaline solutions?
Yellow
Why is a burette used in titrations?
-It can add acid in small increments
-It is more accurate than a measuring cylinder
What colour is phenolphthalein in alkaline solutions?
Pink
