sc14, quantative analysis (paper 1) Flashcards
what is the yield
the mass of a product made in a chemical process
what are the two main rules in any chemical reaction
- no atoms are gained or lost
- the total mass stays the same
what is the theoretical yield
for a given mass for a limiting reactant, you can make only a maximum mass of a product
what is the actual yield
the mass of the product that you really get at the end of a chemical process
true or false: the actual yield is always less than the theoretical yield
true
true or false: the actual yield is always more than the theoretical yield
false
how do you calculate the percentage yield
(actual yield / theoretical yield) x 100
true or false: a higher percentage yield means more mass is made
true
true or false: a lower percentage yield means less mass is made
true
true or false: a higher percentage yield means less mass is made
false
true or false: a lower percentage yield means more mass is made
false
what are the three main reasons for now obtaining the theoretical yield
- incomplete reactions
- side reactions
- practical losses
what does a complete reaction mean in terms of not obtaining the theoretical yield
reaction hasn’t finished or reached equilibrium
what does a side reaction mean in terms of not obtaining the theoretical yield
competing/unwanted reactions can cause by-products to be mae
what does a practical loss mean in terms of not obtaining the theoretical yield
losses during purification (e.g filtration) or transfers (e.g liquid left behind in containers)