quantitative chemistry Flashcards
(19 cards)
What does the law of conservation of mass state?
No atoms are lost or made during reactions so the mass of the products equals the mass of the reactants.
What is the relative formula mass of a compound?
The sum of the relative atomic masses of all the atoms shown in the formula.
In a balanced equation, what is true about the relative formula masses of reactants and products?
The sum of the relative formula masses of all the reactants equals the sum of the relative formula masses of all the products.
A mole of a substance is equal to its relative atomic mass or relative formula mass in _______.
grams
What is the value of Avogadro’s constant?
6.02 x 10^23
How do you calculate the number of moles?
Number of moles = mass (g) / Ar or mass (g) / Mr
What do balanced symbol equations show?
The number of moles of each substance involved in the reaction.
What is the limiting reactant?
The reactant that gets used up first in a reaction.
How can the concentration of a solution be measured?
In mass per volume, specifically grams per dm3 (g/dm3).
What is the relationship between dm3 and cm3?
1 dm3 = 1000 cm3
How do you calculate the mass of solute in a solution?
Mass of solute = concentration x volume in dm3
How can the concentration of a solution be increased?
By increasing the mass of solute or decreasing the volume of the solvent.
How can the concentration of a solution be measured in another unit?
In mol/dm3
How do you calculate the amount of moles of solute?
Amount of moles of solute = concentration x volume in dm3
What is the formula for % yield?
% yield = (mass of product actually made / maximum theoretical mass of product) x 100
Why is it not always possible to obtain 100% yield?
The reaction may not go to completion or some of the product may be lost when it is separated from the reaction mixture.
What is atom economy?
A measure of the amount of starting materials that end up as useful products.
How is atom economy calculated?
Atom economy = (relative formula mass of desired product from equation / sum of the relative formula masses of all the reactants from the equation) x 100
What is the volume of one mole of any gas at room temperature and pressure?
24 dm3
