Quantative chemistry Flashcards
What does the law of conservation of mass state?
no atoms are lost or made during a chemical reaction so the mass of products equals the mass of the reactants
How do you calculate the relative formula made of a compound?
adding up the relative atomic masses of all the atoms present
I’m a balanced chemical equation what does the sun of the relative formula masses of the reactants in the quarries shown equal?
the sun of the relative formula masses of the products in the quantities shown
What are some examples of reactions that appear to involve a change in mass?
gases lost or gained from the atmosphere
What is meant by measurement uncertainty?
the margin of doubt that exists for the result of any measurement
What are chemical amours measured in and what is the unit?
moles (mol)
what is the number of atoms, molecules or ions in a mole of a given substance?
Avogadro constant
What is the mass of one mole of a substance in grams equal to?
it’s relative formula mass
How do you calculate the masses of substances shown in a balanced symbol equation?
mr mr table
How do you calculate the masses of reactants and products from the balance symbol equation and the mass of a given reactant or product?
mr mr table
How do you balancing equation?
using a table
What does it mean if a reactant is the limiting reactant?
the reactant that get consumed first in a chemical reaction and therefore limits how much product can be formed
What does it mean if a reactant is in excess?
a substance that is not wholly consumed or entirely reacted
What can the concentration of a solution be measured in?
Mass given volume of solution (g/dm3)
How is the mass of a solute and the volume of a solution related to the concentration of the solution?
concentration can be increased by dissolving more solute in a given volume of solution. this then increases the mass of the solute.
Why is it not always possible to obtain the calculated amount of product from reaction?
the reaction may not go to completion because it is reversible or some product may be lost
What is the amount of product obtained known as?
Yield
What is percentage yield?
how much product is obtained compared to the maximum possible mass
How do you calculate the percentage yield of a product from the actual yield of a reaction?
actual yield divided by theoretical yield x 100
What is the atom economy?
Measure of the amount of starting materials to end up as useful products
Why is atom economy important?
a reaction with high atom economy is important for sustainability because it uses fewer natural resources and produces less waste
How do you calculate the atom economy of a reaction?
total mr of desired product/ total mr of all products x100
What is concentrate measured in?
mol/dm3
How do you calculate the amount of moles of solute or the mass in grams of salt in a given volume?
Mass/volume
What is the volume of one mole of any gas at room temperature and pressure?
24dm3
What can the volumes of gaseous reactants and products be calculator from?
Balanced equation for the reaction
How do you calculate the volume of a gas at room temperature?
moles/volume
