Module 2: Introduction to Quantitative Chemistry Flashcards
What is the law of conservation of mass?
Matter can’t be created or destroyed
Total mass of products = total mass of reactants
Chemical bonds between atoms are broken, and new bonds are formed
what is the difference between and open and closed system?
Closed= a quantity or series of quantities cant enter or leave the system open= a quantity or series of quantities can enter or leave the system to a significant degree. The mass can change over time
What is stoichiometry?
stoichiometry is using a balanced chemical equation to calculate amounts of reactants and products. They are based on the law of conservation of mass.
what is a mole?
a unit of measure that helps compare particles of any given substance and its mass
6.022 times 10(power of 23)
converting mass formula:
n= m/ MM
How do you find number of atoms?
Calculate number of moles
Calculate number of molecules (multiple by Avos. no.)
Calculate no of atoms (times)
what is percentage composition formula?
mass/total mass x100
what is avogadros number
1 mole = 6.022 × 1023
how do you find molar mass?
Find the atomic mass of individual elements
Count how many atoms there are for each element
Add atomic masses together to find MM
how do you calculate the empirical formula?
Write down masses of all elements present in a given sample of a compound
Convert masses into moles
Divide by the smallest number of moles to get a simple ratio
If the numbers are not close to whole numbers, multiply by a suitable factor to make them whole numbers
Round off numbers and use them to write the emp. formula
Experiment: theoretical value vs experimental value
The experimental value may differ from to theoretical value due to error in the experiment.
We should learn that chemicals react in simple whole number ratios by moles
what does the coefficient in front of a balanced chemical equation equal?
the mole ratio
what is a limiting reagent?
The reactant that is all used up first is called the limiting reagent because it limits the amount of product that can be formed.
what are most solutions measured in?
moles per litre (M)
define molarity:
Defined as the number of moles of solute per litre of solution.
what is the molarity formula?
C= n/v n= number of moles c= concentration in (moles per litre) v= volume in litres
How do you dilute a solution?
we do this by first measuring out a volume of the original solution and adding water to make the new volume. Both solutions have the same number of moles of solute but a different volume. Therefore, they have different concentrations.
concentration solution vs diluted solution formula
C2) Concentration of diluted solution x (V2) volume of diluted solution =
(C1) original concentration x (V1) volume of original solution
Why are gases so different to liquids and solids?
their volumes are very sensitive to pressure and temperatures
Formula for celsius into kelvins:
T(K) = C + 273.15
Avogadro’s law:
Equal volumes of gases contain equal numbers of molecules (at same temp and pressure).
One mole of any gas has the same volume (at same temp and pressure).
Because a mole is a fixed number of molecules a mole of any gas has the same volume as the mole of any other gas. This volume is called the molar volume of a gas.
Boyles law states:
For a given quantity at a constant temperature, the product of its volume and pressure is constant.
Volume is inversely proportional to pressure.
Boyles law formula
p1v1= p2v2
Charles law states:
f a given quantity of a gas is held at a constant temperature;
Its volume is directly proportional to the temperature
