3.1.2 Amount of substance Flashcards
What is relative molecular mass (Mr)?
The mass of one molecule relative to 1/12 the mass of one atom of carbon-12.
What is relative atomic mass (Ar)?
The average mass of one of its atoms relative to 1/12 the mass of one atom of carbon-12.
What is empirical formula?
The simplest whole number ratio of atoms of each element in a compound.
How do you figure out which parts of the equation are a part of the ionic equation?
The parts which change state or are a part of a new molecule.
Do isotopes have different physical or chemical properties to the element?
Physical properties as electrons change chemical properties.
What is atom economy?
The proportion of the reactant’s atoms that end up in the useful products.
Why can the yield sometimes be above 100%?
The solid is wet.
What is relative formula mass?
It can refer to Mr or Ar. It is the general term.
Why do we want a high atom economy?
-Minimises waste of non-renewable reactants.
-Makes as much useful product as possible.
-Reduces pollution from waste products.
Why can the yield be less than 100%?
-Side reactions
-The reaction may be reversible.
-The reaction is incomplete.
-Product is lost in transfer losses
-Gas product may be lost.
How many particles are there in one mole?
Avagadro’s number of particles.
How can you figure out the number of hydrogen atoms in NH3?
Using the moles and Avagadro’s constant, calculate the number of NH3 molecules and then multiply by 3.
What is the concentration of a substance measured in?
moldm-3
How do you convert the empirical formula to the molecular formula?
Divide the Mr of the molecular formula by the Mr of the empirical formula to find the ratio.
What is molecular formula?
The actual number of atoms of each element in a compound.
