Unit 2 Quantitative Chemistry Flashcards
What is the definition of concentration?
A measure of how much of a substance is dissolved in a known amount of water.
How can you calculate concentration in g/dm2?
. Mass of solute (g)
Concentration = ————————-
. Volume (dm2)
How do you calculate concentration in mol/dm3
. n
c = —
. v
Remember the triangle:
. n
. c v
What is 1dm3?
1000cm3 (1 litre)
(Remember how to convert this)
How can you convert between concentration in g/dm3 to mol/dm3
g/dm3 —> mol/dm3
Divide by RFM
Mol/dm3 —> g/dm3
Multiply by RFM
How do you calculate mass from moles?
m
n RFM
What is Titration?
A method of reacting two solutions together to determine the concentration of one of the solutions
How do you prepare a burette?
Rinse with deionised water
Rinse with the solution
Fill with the solution
Allow the solution to run out until the bottom of the meniscus is on the zero line.
Ensure the tip is full and there are no air bubbles.
How do you prepare a pipette?
Rinse with deionised water
Using a pipette filler:
-rinse with the solution
-fill with the solution
Holding the pipette vertically with the volume at eye level, run out the solution until the bottom of the meniscus is on the line.
How would you carry out a titration experiment?
Prepare the burette and fill with hydrochloric acid.
Pipette 25cm3 of sodium hydroxide into a conical flask using a pipette filler.
Add three drops of phenolphthalein indicator. Swirl the flask gently.
Add the hydrochloric acid from the burette, swirling gently to mix the solutions.
Stop adding the acid at the end point (At the end point of this titration the indicator will change from pink to colourless).
Record the volume of hydrochloric acid added.
What is Molar gas volume?
The volume of one mole of gas under specified conditions of temperature and pressure e.g. 24dm3 at 293K(20 degrees Celsius) and one atmosphere pressure.
How do you calculate number of moles of gas using molar gas volume?
. Gas volume (V)
Number of moles of gas (n) = ———————————
. Molar gas volume (Vm)
What is Atom economy?
A measure of how efficiently the atoms in the reactants are used and converted to the desired product in a chemical reaction.
How do you calculate % atom economy?
Mass of desired product
—————————————- x 100
Sum of mass of all products
What is the:
Control variable
Independent variable
Dependant variable
Thing that stays the same
The thing we change
Thing we measure
