2.1.3 Amount of Substance Flashcards
What is the symbol for amount of substance?
n
What is the unit used to measure amount of substance?
Mole
What does Avogadro constant represent?
The number of atoms per mole of the carbon 12 isotope
How to calculate the mass of 1 mole of the element?
Mass of 1 mole = relative atomic mass in grams
How do you calculate moles when mass and molar mass are given?
Moles (mol) = mass (g) / molar mass (g/mol)
State Avagadro’s law
Under the same temperature and pressure one mole of any gas would occupy the same volume
How much volume does a gas occupy at room temperature and pressure?
24 dm³
Define molar gas volume
The volume per mole of gas molecules
Why do different gas particles occupy the same volume?
The gas particles are very spread out hence individual differences has no effect
How to calculate moles when volume is given?
Moles (mol) = volume (dm³)/24
What are the ideals ways in which gases behave
- They are in continuos motion
- No intermolecular forces experienced
- Exert pressure when they collide with each other or container
- No kinetic energy is lost in collisions
- When temperature increases, kinetic energy of gasses also increases
Write down the ideal gas equation
pV=nRT
Pressure (Pa) x volume (m³) = Moles (mol). x gas constant (8.314 J/mol) x temperature (K)
1 atmospheric pressure is equal to how many pascals?
1 atm = 101325 Pa
0°C is equal to how many kelvin?
273K
What does concentration of a solution mean?
It is the amount of solute dissolved in 1 dm³ of solvent
How do you calculate moles when concentration and volume are given?
Moles (mol) = concentration (mol/dm³) x volume (dm³)
What is a standard solution?
A solution of known concentration
What does the terms concentrated and dilute mean?
Concentrated - large amount of solute per dm³ of solvent
Dilute - small of solute per dm³ of solvent
What is a species in a chemical reaction?
Any particle that takes part in a reaction
What are the four common state symbols?
- Solid (s)
- Liquid (l)
- Gaseous (g)
- Aqueous. (aq)
What does percentage yield mean?
The efficiency of which reactants are converted into products
What are the reasons for not obtaining 100% yield?
- Reactions may not be at equilibrium
- The reactants may be impure
- Side reactions may happen
- Reactants or products may be left behind while transferring
- Loss of products during separation and purification
How is percentage yield calculated?
Percentage yield = (actual amount of product (mol) / theorectical amount of product (mol)) x 100
What does atom. economy tell us about?
The proportion of desired products compared with all the products formed in the reaction
How is atom economy calculated?
Atom economy = (molecular mass. of desired product / sum of the molecular masses of all products) x 100
Does 100% yield mean 100% atom economy?
No, even if all the reactants are converted into product, not all products of the reaction will be the required products
Which type of reaction has 100% atom economy?
Addition reactions (two or more reactants are combined to form a product)
