1.0 Formulae, Equations And Amount Of Substance Flashcards
(18 cards)
1
Q
What is an Element
A
- pure substance that consists entirely of one type of atom
- characterized by its atomic number, which is the number of protons in the nucleus of its atoms
- determines its position on the periodic table
2
Q
What is an ion
A
- an atom that has gained or lost one or more electrons, resulting in a net electrical charge.
- CATION: an atom loses one or more electrons, it becomes positively charged
- ANION: an atom gains one or more electrons, it becomes negatively charged
3
Q
What is a molecule
A
- a group of two or more atoms that are chemically bonded together
- atoms can be of the same element or different elements (O2 , H2O)
4
Q
What is empirical formula
A
- simplest whole-number ratio of the atoms of each element present in the compound
- represents the basic ratio between the elements rather than the actual number of atoms in a single molecule of the compound.
- example: Glucose (C₆H₁₂O₆): The molecular formula is C₆H₁₂O₆, but the empirical formula is CH₂O.
5
Q
What is molecular formula
A
- the exact number of atoms of each element present in one molecule of the compound
- shows the actual quantity of each type of atom rather than just the simplest ratio
6
Q
Mole & Adogadro’s constant
A
- unit in chemistry used to measure the amount of substance
- One mole of any substance contains exactly 6.02 x 10^23 mol^-1 particles (atoms, molecules, ions, or electrons) of that substance
7
Q
Relative molecular mass
A
- The total mass of a substance that is molecular ONLY
7
Q
Relative atomic mass
A
- most elements on the periodic table represent a mixture of different isotopes: shown as Relative Atomic Mass (Ar)
- average mass of an atom is relative to 1/12 of the mass of a carbon-12 atom
8
Q
Relative Formula mass
A
- total mass of a substance
- used for compounds with giant structures ONLY : eg ionic compounds NaCl
9
Q
PPM
A
- parts per million
- includes gases in the atmosphere
- way of expressing very dilute concentrations of substances
- 1 PPM means that there is 1 part of a substance for every 1 million parts of the total solution or mixture
10
Q
Mole Formula
A
Number of moles = mass (g)/ molar mass (Ar, Mr)
11
Q
Conc. Formulae
A
conc (mol/dm^3) = number of moles / volume
12
Q
Ideal Gas Law
A
- PV = nRT
- P (pascals)
- V (litres/m^3)
- n (num of moles)
- R (gas constant: 8.314 J/mol.K)
- T (kelvin : celsius + 273)
13
Q
Empirical and Molecular formula
A
Molecular formula = empirical formula x n
14
Q
Percentage yeild
A
(actual yield/theoritical yield) x 100
15
Q
Atom Economy
A
measure of the efficiency of a chemical reaction in terms of the amount of reactant atoms that are incorporated into the desired product
16
Q
Dilution Formula
A
17
Q
Rate of reaction formula
A
rate = change in concentration / time
