Flashcards in C3e Deck (11):
What is percentage yield?
A way of comparing amount of product made, actual yield, to amount expected, predicted yield.
What does 100% percentage yield mean?
No product has been lost/ you got all the product you expected to get.
What does 0% percentage yield mean?
No product has been made/ no reactants were converted into product.
What are the possible reasons why the percentage yield of a product is less than 100%, GIVEN THE DETAILS OF THE EXPERIMENT?
Evaporation - liquids evaporate, especially when heated.
Not all reactants react to make a product - in reversible reactions, the products can turn back into reactants.
Filtration - when you filter a liquid to remove solid particles, you nearly always lose a bit or liquid or solid. If you want to keep the liquid, you lose the bit that remains with the solid and filter paper. If you want to keep the solid, some of it usually gets left behind when you scrape it off the filter paper.
Transferring liquids - you lose a bit when you transfer it from one container to another as some of it always gets left behind on the inside surface of the old container.
What is the formula for percentage yield?
actual yield/predicted yield (x100)
Why does an industrial process want as high a percentage yield as possible?
To reduce the reactants wasted and reduce cost.
What is atom economy?
A way of measuring the amount of atoms wasted when manufacturing a chemical.
What does 100% atom economy mean?
All atoms in the reactant have been converted to the desired product.
What does a higher atom economy mean?
The higher the atom economy, the greener the process.
What is the formula for atom economy?
Mr of desired products/sum of Mr of all products (x100)