TOPIC 3 - QUANTITIVE CHEMISTRY Flashcards
(12 cards)
What is the law conservation of mass?
No atoms are made or lost during a chemical reaction so mass of products = mass of reactants
What number do you use to calculate Mr?
Atomic number (top number)
If a reaction occurs in a open container, why might the mass of the system appear to increase?
- State law of conservation of mass
- Say what the balanced equation shows
- Mass of product is bigger than initial mass
- Oxygen molecules from air collide and react
- Chemically bonded means mass increased
- Total mass of element + oxygen = mass of magnesium oxide
What is Avogadro’s constant worth?
6.02 x 10^23
What is a limiting reactant?
The reactant that is completely used up is called the limiting reactant because it limits the amount of products.
What’s the equation for concentration? (g/dm^3)
mass(g) / volume / 1000
What do you times by to go from mol/dm^3 to g/dm^3
Mr
What’s the equation for concentration (mol/dm^3)
moles / volume / 1000
What’s the equation for % yield?
% yield = mass of product actually made
——————————————- x 100
maximum theoretical mass of product
Percentage atom economy equation =
relative formula mass of desired product
———————————————————– x 100
sum of relative formulas masses of all products
Why do we want a high atom economy?
Higher atom economy means fewer by-products are formed minimizing environmental impact
One mole of any gas occupies a volume of ?
24dm^3
