Calculations involving the mole and balanced equations Flashcards
What is the formula mass definition?
The formula mass of all the atoms in a formula is called the formula mass.
How do we know the each elements relative atomic mass or (RAM) ?
Every element has a unique mass number and it can be found on page 7 of the data booklet.
How do we calculate the formula mass ?
To work out the formula mass of any compound the total mass of all the atoms in the compound must be used. For each type of atom, multiply the formula mass by the number of that atom and then add them all up.
How do we calculate the gram formula mass?
The gram formula mass (GFM) is the formula mass expressed in grams.
What is a mole?
The mole is a unit of measurement. In chemistry, we use it to tell us how many atoms or molecules there are.
What is one mole equal to?
One mole= The gram formula mass of a substance
How do we calculate the mass (M) of a given number of moles (N)?
M=NxGFM
How do we calculate the number of moles (N) of a given mass (M)?
N=M/GFM
What is a state symbol?
State symbols are written, in brackets, after each formula in a balanced formula equation.
What does this state symbol mean (s)?
(s)=solid
What does this state symbol mean (l)?
(l)=liquid
What does this state symbol mean (g)?
(g)=gas
What does this state symbol mean (aq)?
(aq)=In aqueous solution
What must we use when writing a balanced formula equation?
To do this you are using:
The rules for formula
The rules for balancing equations
The correct state symbols
What does a balanced equation show?
A balanced equation shows the mole ratio of the reactants and products.
How can we calculate the quantity of products formed?
If you know the quantity of a reactant used then, using the balanced equation, you can calculate the quantity of products formed.
How does a solution form?
A solution forms when a solute dissolves in a solvent.
How is the concentration of a solution defined?
The concentration of a solution is defined as the number of moles of solute per litre of solution.
What are the units of concentration?
The units of concentration are mol l-1 (moles per litre)
How do we work out the number of moles of a given concentration in moles per litre and volume in litres?
N=CXV
In this equation, the volume must be in litres.
How do we work out the concentration in moles per litre of a given number of moles and volume in litres?
C=N divided by V
In this equation, the volume must be in litres.
How do we work out volume in litres of a given number of moles and concentration in moles per litre?
V= N divided by C
In this equation, the volume must be in litres.
How do we convert cm3 into litres?
To convert cm3 divide by 1000.
What is a standard solution?
A standard solution is a solution of accurately known concentration.
Describe how we form a standard solution?
Measure the mass of solute on a weighing scale
Dissolve in a small volume of water (dissolve solute in a small amount of solvent)
Transfer to standard flask
Rinse all solution into flask with more solvent
Carefully make up to the callibration mark on the flask
Add stopper and shake.
What is a volumetric flask?
A volumetric flask is also known as a standard flask.
