Chemical calculations Flashcards
Relative atomic mass
Average mass of all the isotopes of that element
What is Ar
Atomic mass
What is Mr
Relative formula mass
Mole
Unit to measure the amount of chemical we have of a substance
conservation of mass
No atoms are lost or made during a chemical reaction
State a reason why the mass appear to increase
One of the reactants is a gas
State a reason why the mass appear to decrease
One of the products is a gas
How to avoid mass change during a chemical reaction?
Do experiments inside a sealed container
chemical change?
A rearrangement of the atoms in the reactants to form the products
Limiting reactant?
It determines how much product can be formed
Reactant to be ‘ in excess ‘
Does not all react and has no affect on the amount of product formed
What is the equation for concentration?
conc = mass/vol
Equation for volume of gas
Vol of gas = moles x 24
equation for atom ecoomy
atom ecom = Mr of desired product /
Mr of all reactants x 100
Why is it important to consider atom economy?
- raw material are expensive so if it is
going to turn into waste product the
process is going to be less profitable - Less sustainable to use large
quantities of reactants to make tiny
amount of products - Waste products can damage
environment
