C4 - Chemical calculations + conservation of mass Flashcards
(14 cards)
What is the conservation of mass?
Total mass before a reaction must equal the total mass after a reaction
Why might the mass seem to increase in a reaction?
A gas was a reactant so can now be weighed but couldn’t before
Why might the mass seem to decrease in a reaction?
One of the products was a gas and can’t be weighed
What is a mole?
Mass of a substance that contains 6.022 x 10^23 particles
What is Avogadro’s constant?
6.022 x 10^23
What equation links mass, mole and Mr
Mass = Mole x Mr
What is a limiting reactant?
The reactant that is completely used up in a chemical reaction
How do you convert from cm cubed to dm cubed?
divide by 1000
What is the yield of a reaction?
Mass of a product
What is the theoretical yield of a reaction?
The maximum mass that could’ve been produced
What is the percentage yield of a reaction?
Actual yield as a percentage of the theoretical yield
Why is the actual yield always less than the theoretical yield?
- Reaction may be reversible
- Some product may be lost in separation
- Side reactions could happen
What is atom economy?
A measure of how many of the atoms in the reactants end up as useful products
What volume does one mole of gas occupy at room temperature and pressure
24 dm cubed or 24,000 cm cubed
