Chemistry Quantitative March 2018 Flashcards
What is the equation of moles?
Moles = mass / Mr
What does ‘Mr’ stand for?
Relative formula mass
What is an excess substance?
A substance that there is more than we need
What is a limiting substance?
It dictates the mass of the product
What is the equation for % Yield?
actual mass obtained / calculated mass x 100
What are the definitions for Yield and % Yield?
Yield = The amount of product formed in a reaction.
% Yield = The amount of product gained in a reaction compared to the maximum theoretical mass.
What is the definition for atom economy?
A way of measuring what percentage of the mass of all atoms in the reactants ends up in the desired products.
What is the equation for atom economy? (%)
Mr of desired product / Σ Mr of all reactants x 100
Σ = sum of
If there is only 1 product what is the atom economy (%)?
100%
1 dm^3 = ?
1 L or 1000 ml
What is the equation for the moles of gas?
moles of gas = volume (dm^3) / 24
What is the definition of concentration?
A measure of how much solute (solid) is dissolved in a solvent (water)
If you have 90g of H2O, how many moles is there?
Mr = 2 x 1 + 16 moles = mass / Mr = 90 / 18 = 5 moles
If you have 102 tons of O2, how many moles do you have?
102 tons = 102,000,000g
Mr = 16 x 2 = 32
moles = mass / Mr = 102,000,000 / 32 = 3,190,000 moles or 3.19x10^6 moles.
If you have 4 moles or N2, how many grams do you have?
Mr = 2 x 14 = 28 moles = mass / Mr so mass = moles x Mr mass = moles x Mr = 4 x 28 = 112g