Quantitative Chemistry Flashcards
(22 cards)
How do you calculate the Relative Formula Mass of a substance? - Calculations
Add all the Mr together of each individual atom in a substance
What is the law of conservation of mass? - Calculations
No atoms are lost or made over the course of a reaction. This means the mass of the products is the same as the mass of the reactants
How can reactants often have different masses to products when measured? - Calculations
In an open system, products are often formed as gases which can escape from measurement of products
How should you calculate uncertainty? - Calculations
Divide the resolution of a measuring implement by 2 and give your answer in a +/- form
What is the concentration of a substance? - Calculations
The number of particles in a given volume
What is the unit of concentration? - Calculations
g/dm^3
How can you convert cm^3 to dm^3? - Calculations
Divide your cm^3 value by 1000 to convert to dm^3
Multiply your dm^3 value by 1000 to convert to dm ^3
What is the Avogadro constant? - Calculations
The number of atoms in 1 mole of a substance: 6.022 x 10^23
What is the equation to calculate the mass of a substance using moles? - Calculations
Mass = Mr x Moles
MR MOLES
What is a limiting reactant? - Calculations
A reactant that is entirely used up in a reaction. The other reactant is described as being added in excess
What is the equation to calculate concentration? - Calculations
Moles = Concentration (vol/dm^3) x volume (dm^3)
How should you convert from g/dm^3 to mol/dm^3? - Calculations
Divide the value of g/dm^3 by the Mr of the substance
What are by-products of reactions? - Calculations
Something produced during a reaction which is not the desired product
What is the atom economy of a reaction? - Calculations
A measure of how many reactant atoms form a desired product
How do you calculate the atom economy of a reaction? - Calculations
Atom economy = (total Mr of desired products / total Mr of all reactants) x 100
What is percentage yield? - Calculations
The actual amount of a product formed by a reaction compared to the theoretical amount of a product that can be formed
How do you calculate percentage yield? - Calculations
Percentage yield = (mass of product formed / maximum theoretical mass of product that can be formed) x 100
What is Avogadro’s law? - Calculations
Equal volumes of different gases contain an equal number of molecules when temperature and pressure are kept the same
What is the equation for volume when moles is used? - Calculations
Volume = 24 x moles
What is the moles equation?
Moles= mass/ Mr
What is the volume of 1 mole of any gas at room temperature?
24dm^3
What equation relates number of moles of gas, volume and molar volume of gas?
number of moles of gas= volume (dm^3)/ 24 dm^3
Or
number of moles of gas= volume (cm^3)/ 24,000 cm^3
