Topic 5 Flashcards
What is a mole?
A mole is the amount of substance that contains the same number of particles as the number of carbon atoms in exactly 12g of the carbon-12 isotope
What is Avogadro’s constant
- Avogadro’s constant is a scaling up factor
- 6.02 * 10^23 mol-1
How do you calculate the number of particles in a given mass of substance?
How to calculate the mass of a given number of particles of a substance?
What are the calculations using reacting volumes of gases?
What is the equation for calculating moles?
n = amount of substance in mol
m = mass in grams
M = Molar Mass
How do you calculate reacting masses from equations?
How do you work out equations from reacting masses?
ow to calculate moles from volume and concentration?
What is Molar Volume?
Molar Volume is 1 mole of gas at room temperature and pressure
- Room Temp = 25 degrees Celsius
- Standard Pressure = 1 atm
What is empirical formula?
Empirical formula shows the smallest whole number ratio of atoms o each element in a compound
How do you calculate empirical formula from masses?
How do you calculate molecular formula from percentages?
What is molecular formula?
- Molecular formula is the actual numbers of atoms in each element in a compound
- Requires relative molecular mass and empirical formula to calculate
How do you calculate molecular formula for solids and liquids?
How do you calculate molecular formula for gases and volatile liquids?
How do you write out ionic equations?
How do you calculate Mass from moles and Mr?
How do you calculate mass from moles and molar mass?
How do you calculate volume from gas constant and pressure?
How do you calculate volume from molar volume?
How do you calculate the concentration of a solution?
How do you calculate percentage uncertainty?
What are potential sources of error?
Random Error (Unpredictable changes)
- Volume of Gas collected could vary from different times of day
- Changed in temperature throughout the day may lead to different masses
Systematic Errors (Faults in apparatus)
- Uncalibrated pipette during manufacturing where the meniscus line is incorrect
- Measuring cylinder may have incorrect measurements proportional to the actual size of the cylinder
How can you minimise the percentage error?
- Use better equipment like gas syringe over water trough and measuring cylinder
- Use more reactant to create more product which can be measured more accurately
- Use smaller increment versions of equipment like 3d.p balance over 2.dp balance
Why is actual yield always less than theoretical yield?
The mass of product is never the maximum possible because:
- Reversible reactions may be incomplete
- Unintended side reactions create unwanted products
- Further purification of product leads to a loss of product
How do you calculate theoretical yield?
What is the percentage yield formula?
How do you calculate percentage formula?
What’s the Definition for Atom Economy?
Atom Economy is the measure of proportion of reactant atoms that become part of the desired product.
How does atom economy work?
The RED PROCESS is inefficient because there are multiple products made.
The GREEN PROCESS is efficient because all the reactants form the only desired product.
What the links between reaction types and atom economy?
Atom Economy in Different Reaction Types
- Addition = 100% atom economy
- Elimination + Substitution = Lower atom economies
- Multistep = Lower Atom Economies
5.15
