C4 - Chemical Calculations Flashcards
Remember to do worked equations aswell
What is Avogadros constant?
One mole of a substance contains 6.02 x 10*23 atoms
What is the equation triangle for Moles, Relative mass and mass
. Mass m
—————– ———–
Moles | Relative Mo | Mr
Mass
How do you calculate the pecentage yield?
actual yield
————————- x 100
Theoretical yield
How would you calculate the atom economy?
Mr of useful product
——————————- x 100
Mr of all reactants
What is the unit for concentration?
g/dm*3
How do you calculate concentration?
Mass (g)
————————- = Concentration (g/dm3)
Volume (dm3)
How do you calculate the volume in dm3 from cm3?
Volume(cm3) / 1000 = Volume (dm3)
How much cm are in 1 dm?
1000 cm
What is the limiting reagent?
The reactant that runs out
What is the excess in a reactant?
The reactant that is left over
Solve this question.
What mass of oxygen reacts with 12g of magnesium?
2Mg + O2 —–> 2MgO
workout by hand
8g
How do you find the number of MOLES in a given mass?
Number of Moles = mass in g / Mr
What does does not happen to the atoms during chemical reaction that many get confused about?
In a chemical reaction, No atoms are destroyed and no atoms are created
What must you do to ‘Show that a mass is conserved in a given reaction’ ?
Prove the reactant Mr is equal to the product Mr
When do reactions stop?
When one reactant is used up
What is the relationship to the limiting reactant and product formed?
The amount of product formed is directly proportional to the amount of limiting reactant
How much decimetres does one mole of any gas at 20°C occupy?
24dm°3
What is the equation to find out the volume of any gas at room temperature?
Volume of gas = Mass of gas / Mr of gass X 24
How do you calculate the concentration of a solution with the given mass of the solute?
Concentration = mass of solute / volume of solvent
How do you calculate the concentration of a solution with the given moles of the solute?
Concentration = number of moles of solute / volume of solvent
What would 100% atom economy mean?
All the atoms in the reactants have turned into useful products
The higher the atom economy, the ____________ the process
Environmentally friendly
What are the benefits of higher atom economy?
Better for profits
Better for the environment
What does the percentage yield tell you?
The overall success of an experiment
What does the percentage yield compare?
The theoretical yield and the actual yield
(What you think you should get with what you actually get)
What is a yield?
The amount of product you get
Why are yields always less than 100%?
Some product or reactant can get lost in the reaction
