What does Ar stand for?
Relative atomic mass
What does Mr stand for?
Relative molecular mass
How is Mr calculated?
Add the Ar of each element together
What is the equation for moles?
Moles = mass (g) / Ar or Mr
What is the equation for mass?
Mass = moles x Mr
What is the concentration of a solution?
Amount of solute that is dissolved in 1dm3^ of a solution.
What is 1dm3^ equal to?
1 litre = 1,000ml
What is the first equation for concentration?
Concentration (g/dm3^) = mass of solute (g) / volume (dm3^)
What is the second equation for concentration?
Concentration (mol/dm3^) = moles / volume (dm3^)
How is g/dm3^ calculated?
g/dm3^ = mole/dm3^ x Mr
What is the method for preparing the burette in a titration experiment?
- Rinse burette with solution it is to be filled with and discard rinsing.
- Fill burette with solution.
- Make sure that jet is filled and that there are no air bubbles.
- Record volume at bottom of meniscus at eye level.
What is the method for preparing and using the pipette in a titration experiment?
- Rinse pipette with solution to be placed in conical flask.
- Using pipette filler, draw up solution until bottom of meniscus is on the line on pipette.
- Release liquid into conical flask.
- Touch pipette on surface of liquid to remove last drop from pipette.
What is the method for carrying out the titration in a tritiation experiment?
- Measure out volume of solution (usually 25.0cm3^) using pipette and pipette filler, and place it in conical flask.
- Add a few drops of indicator, such as methyl orange or phenolphthalein.
- Add other solution from burette, swirling contents of conical flask until indicator just changes colour. This is the end point. Read volume delivered using bottom of meniscus at eye level, and record value. This is a rough titration.
- Repeating titration, this time add solution from burette drop wise near end point. Read and record volume added from burette. This is an accurate titration.
- Carry out several accurate titrations and calculate average of volume delivered from burette to obtain final value.
What is the equation for finding the new concentration in a diluted solution?
New concentration = Original concentration x original volume / new total volume
What is method for diluting a solution?
- Wear eye protection.
- Rinse a pipette with the solution to be diluted.
- Pipette 25.0cm3^ of the solution into a 250cm3^ volumetric flask.
- Add deionised water until the bottom of the meniscus is on the line.
- Stopper, invert and shake the flask to mix the solution.
What is the method for titration calculations to identify unknown compounds?
- Calculate number of moles of hydrochloric acid used in titration.
- Calculate number of moles of MOH present in 25.0cm3^ of solution in conical flask.
- Calculate number of moles of MOH present in 100cm3^ of solution.
- Determine relative formula mass of MOH.
- Identify element M.
What is the colour change of methyl orange from acid in conical flask and alkali in burette in a titration?
Red to yellow.
What is the colour change of methyl orange from alkali in conical flask and acid in burette in a titration?
Yellow to red.
What is the colour change of phenolphthalein indicator from acid in conical flask and alkali in burette in a titration?
Colourless to pink
What is the colour change of phenolphthalein indicator from alkali in conical flask and acid in burette in a titration?
Pink to colourless
What is a gas volume?
One mole of all gases at room temperature (20oC) and pressure (1atm) has a volume of 24dm3^.
What is the equation for the mole of gas?
Mole of gas = volume (dm3^) / 24
What is the equation for atom economy?
Atom economy = mass of desired product / total mass of products x 100
What is Avogadro’s Law?
Equal volumes of gas contain the same number of particles under same conditions of temperature and pressure.
