Amount of substance Flashcards
How do you convert from degrees to kelvin ?
+ 273
Why is percentage yield important to know ?
It gives you and idea of how efficient the conversion from products to reactants is.
What is percentage yield ?
Actual yield x 100 / Theoretical yield
what steps would you do to answer this question ?
A standard solution has 0.5 grams of NaOH with volume of 250cmcubed The titre reading is 4.2 cm cubed calculate concentration of acid.
Calculate moles in standards solution and use scale factor.
Use ratio to calculate moles of acid.
Use c = n/v
How do you make a standard solution (6 marks) ?
Add sample to a weighing boat then measure mass then transfer to a clean dry conical flask.
Measure mass of empty weighing boat and calculate mass of sample used.
To conical flask add de-ionized water and still till completely dissolved.
Transfer solution to a volumetric flask including washings.
Add more de-ionized water to volumetric flask until fill line.
Upturn sealed flask multiple times to ensure even concentration of sample throughout.
What is relative atomic mass ?
Average mass of 1 atom of a element divided by 12th the mass of a carbon12 atom.
What equation links mass moles and mr ?
Moles = M/mr
How do you convert from cm^3 to dm ^3
Divide by 1000.
What is the formula for concentration and what are its units ?
Concentration = Mass / Volume
mol/dm^-3
What is the gas constant ?
8.31
How many atoms are in a mole ?
6.022x10^23
What is the deal gas question and what are the units for these ?
PV = nRT
P - pascals
V - m^3
T - Kelvin
How do you calculate percentage error ?
error of equipment x 100 / amount of times equipment has been used to measure
What is relative molecular mass ?
Average mass of a molecule divided by 12th mass of a carbon 12 atom.
What is atom economy ?
mass of desired product x 100 / total mass of reactants
