Quantative chemistry

• The law of conservation of mass is that no atoms are lost or made during a chemical reaction so the mass of product equals the mass of the reactants.
• Ionic compounds are formed when metals react with non-metals.
• Metals form positive ions and non-metals form negative ions.
• Transition metals can form several ions.
• In an ionic compound, the charges on the overall ions have to cancel out to leave an overall charge of zero.
• When your balancing equations your never allowed to change the small numbers in a chemical formula as this produces a differnent molecule.
• Relative atomic mass of an element is the average mass of the isotopes of that element weighted to take into account the abundance of each isotope.
• Relative formula mass of a compound is the sum of the relative atomic masses of the atoms in the number shown in the formula.
• The percentage by mass tells is what percemtage of the relative formula mass is due to one fo the elements in a compound.
• Percentage by mass of an element = Total relative atomic mass of the element / Relative formula mass of a compound x 100
• Number of moles of an atom = Mass (g) / Relative atomic mass (Ar)
• Number of moles of a compound = Mass (g) / Relative formula mass (Mr)
• Avagadro constant is 1 mole and is represented as 6.02 x 10^23
• 1 mole contains one avagadro constant.
• Limiting reactant is the reactant that is used up first in a chemical reaction.
• A solute is a chemical that is dissolved in a solvent.
• Water is often used as a solvent.
• The unit of concentration is g/dm^3.
• concentration (g/d^3) = mass (g) / volume (dm^3)
• If we increase the mass of solute and keep the volume the same, then we increase the concentration.
• If we increase the volume of the solution and keepm the mass the same, then we decrease the concentration.