Quantative Chemistry Flashcards
(19 cards)
How do you calculate the % mass of an element in a compound?
Mr of the compound
On a periodic table what is the bigger number next to the elements symbol?
The relative atomic mas
What is a mole?
A name given to an amount of a substance
What is one mole of atoms or molecules of any substance will have a mass in grams equal to the…..
Relative formula mass
What is carbons Ar?
12
What is the formula for the number of moles?
Mr (of an element or compound)
Are any atoms destroyed during a chemical reaction? What does this do to the mass?
No, none are destroyed or created. Because of this no mass is lost or gained so the mass is conserved during a reaction.
If the mass seems to change during an experiment what is usually involved? Why?
A gas, as it is a reactant found in the air and the products are solids, liquids or aqueous. (vice versa)
What happens if one reactant gets completely used up? What is this called?
The reaction will stop this is called limiting.
what is the amount of product dependant on?
The limiting reactant.
What are the 5 steps to calculating the mass of a product?
1-Write out the balance equation.
2-Work out the relative formula mass, of the reactant you want.
3-Find out how many moles there are of the substance you know the mass of.
4-Work out how many mole there will be in the other substance .
5-Use number of moles to calculate the mass.
What is the formula for the volume of gas?
Mr of gas
What is concentration a measure of?
How crowded things are.
What if the formula for the concentration?
volume of solvent
What if the formula for the concentration mol/dm3?
Volume of solvent
What is the atom economy?
Of a reactant how much of the mass of the reactants is wasted when manufacturing a chemical.
What does percentage yield compare?
Actual and theoretical yield.
What is the formula for percentage yield?
= Mass of product actually made
————————————————– x 100
Maximum theoretical mass of product
Do you ever get 100% percentage yield? Why?
No, not in real life. Because not all the reactants react to make a product, there might be side reactions or you lose some product hen you separate it from the reaction mixture.
