C4 chemical calculations Flashcards
What is a proton?
a subatomic particle that has a positive charge and that is found in the nucleus of an atom.
What is a neutron?
A subatomic particle that has no charge and that is found in the nucleus of an atom.
What is an electron?
A tiny particle with a negative charge. Electrons orbit the nucleus in atoms or ions.
What is a nucleus.
the positively charged dense centre of an atom.
What is a mass number?
the sum of the number of neutrons and protons in an atomic nucleus.
What is an atomic number?
The number of protons (which equals the number of electrons) in an atom. It is sometimes called proton number.
What is an isotope?
one of two or more atoms with the same atomic number but with different numbers of neutrons.
What is relative atomic mass?
The weighted mean of the relative isotopic masses of an element on the scale where carbon-12 is exactly 12.
What is a relative formula mass?
The sum of the relative atomic masses of the elements as given in the formula for any non-molecular compound.
What is a mole?
The amount of substance in the relative atomic or formula mass of a substance in grams.
What is a reactant?
a chemical substance that is present at the start of a chemical reaction.
What is a product?
a chemical substance formed as a result of a chemical reaction.
Define a limiting reactant/ reagent
The reactant that gets used up first in a reaction.
What is a reversible reaction?
A chemical reaction in which the products re-form the original reactants.
Define a yield.
The mass of product that a reaction produces.
Define a percentage yield.
The ratio of the actual yield to the theoretical yield, multiplied by 100.
What is an atom economy?
The ratio of the relative formula mass of the desired product to the total mass of products, multiplied by 100.
What is Empirical formula?
The simplest ratio of elements in a compound.
Define a molecular formula.
a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms.
Define concentration (mol/dm3)
The number of moles of a substance divided by the volume of the solution, in dm3 (litres).
Define concentration (g/dm3)
The mass of a substance divided by the volume of the solution, in dm3 (litres.
What is titration?
A method for measuring the volumes of two solutions that react together.
What is a burette?
long glass tube with a tap at one end and markings to show volume of liquid; used to add precisely known volumes of solution in a conical flask below it.
What is a pipette?
A glass tube used to measure exact known volumes of solution?
What is an end point?
The point in a titration where the reaction is complete and titration should stop.
What is the volume of most gasses?
One mole of any gas occupies 24 dm3.
Equation for moles?
Moles= mass/Mr or Ar
What is the percent composition of an element in a compound?
N x molar mass of element
——————————————. X100%
Molar mass of compound
How do you calculate the % yield ?
Actual yield
———————- X100%
Theoretical yield
What is the equation for concentration ?
Moles
————-
Volume
