Key concepts.3 Flashcards
What’s the law of conservation of mass
The total mass of reactants and products stays constant during a chemical reaction. The total mass before and after a reaction is the same
What’s a closed system
Is a situation in which no substances can enter or leave during a reaction
What can closes systems include
Reactions in a sealed container
Such as a flask fitted with a bung
Precipitation reactions in a beaker
What happens in a precipitation reaction?
Two soluble reactants form an insoluble product - the precipitate
For example
NaCl(aq) + AgNO3(aq) -> NaNO3(aq) + AgCl(s) which forms a white cloudy precipitate
Total mass of the beaker and its contents stays the same during the formation of the silver chloride previpiatate
What’s a non enclosed system ?
A situation in which substances can enter or leave during a reaction
A balanced chemical equations is also called a
Stoichiometric equation
The mass of product is directly proportional to the
Mass of the limiting reactent
What are th types of reactions
Reaction and limiting reaction
What’s a solution
Mixture of a solute in a solvent
What’s a solute
The substance which dissolves
What’s the solvent
The substance that the solute dissolves in
1 dm^3 =
10 x 10 x 10 = 1000cm^3
How do you convert cm^3 to dm^3
Divide by 1000
What do you need to calculate the concentration of a solution
The mass of the solute in grams
Volume of the solution in cubic decimetres
Equation for concentration
In g dm^-3
Mass of solute(g) / volume of solution (dm^3)
Why does g dm^-3 mean
Grams per cubic decimetre
Also see it written as g/dm^3
What’s the unit for an amount of a substance
A mole
The mass of 1 mol of Particles is the
Relative particle mass in grams
What is Avogadros constant
6.02 x 10^23 mol^-1
The mass of 1 mol of a substance is it’s Ar or Mr in grams these are examples
Carbon, C, Ar, 12 mass of 1 mol=12g
Oxygen, O2, Mr, 32 mass of 1 mol = 32g
How do u calculate the amount of a substance from a given mass
Amount (mol) = mass/Ar(Mr)
Moles = grams/rams
