C2.6 Quantitative Chemistry Flashcards
How do you calculate the Relative Formula Mass?
The sum of the relative atomic masses of all the atoms in the formula
Calculate the relative formula mass of Methane
C = 1 x 12 =12
H= 4 x 1 = 4
12+4=16
What is the Empirical Formula?
The simplest whole number of ratio of atoms of each element in a compound
What is the formula for % of an element?
Element% = number of atoms x relative mass of element/relative mass of compound x 100
What do many reactions produce?
Waste Products that aren’t commercially useful
What do waste products cause?
Environmental problems
Social Problems - Houses prices are affected
What do chemists in the industry work to find?
To find economically most favourable reactions
Give examples of most favourable reactions Chemists find
All percentage yield is high (reduces costs)
All of the products of a reaction are commercially useful (no waste products)
The reaction occurs at a suitable speed - the longer it takes, the more expensive it becomes
What are By-products and what can they do?
By products are useful and can be sold to other people
What is a Yield?
The mass of a product obtained in a reaction
What is the Yield less than expected?
The actual yield of a reaction is usually less than the yield calculated using theoretical yield
What is the formula for Percentage Yield?
Percentage Yield = Actual Yield/Theoretical Yield x 100
What are the factors/reasons why reactions don’t give the Theoretical Yield?
Experimental Losses - Some of the chemicals will always be left in beakers
Impure Reactants - Less of the reactant is expected if some of the chemicals at the start were contaminated
Incomplete Reaction - Some of the reactants have not been converted into products
Side Reactions - These are different reactions that turn reactants into by-products
