Unit 1: Stoichiometric Relationships

Do Now 9/14/15 – 5 min The lengths of the sides of a wooden block are measured and the diagram shows the measured values with their uncertainties. 1. What is the percentage and absolute uncertainty in the calculated area of the block? 40.0 ± 0.5 mm 20.0 ± 0.5 mm

Topics in this unit:  Atomic theory, states of matter, elements and compounds, writing balanced reactions, SI units, the mole, empirical formulas, stoichiometry, limiting reactant, concentrations of solutions, gas laws, titrations  Recommended time on this unit from IB: 13.5 hours????  We spent a whole month on stoichiometry/limiting reactants last year  A week on titrations  A week on reading/balancing reactions  A week on the mole  Week on solutions  2 days on states of matter  1 day on elements vs compounds  Didn’t cover gas laws at all….  You will have to read on your own. Make sure you are coming in right away as questions occur.

SI Units PropertyUnitSymbol masskilogramkg temperaturekelvinK timeseconds amountmolemol electric currentampèreA lengthmetre (meter)m luminositycandelacd  All other units are derived from these units  other prefixes (nano, milli, centi, deci, etc)  As we discussed the common IB unit of volume is dm 3 which is = to 1L

Matter  Types of Matter  Element- contains elements of only one type  Compounds – atoms of elements combined in a fixed ration and are made of molecules or ions.  Mixtures – Two substances combined physically  Can be separated physically (distillation, chromatography, magnets, flitration…etc)  Homogeneous –uniform composition (salt water, metal alloys)  Heterogeneous – non-uniform composition (salad dressing, garden soil)

Matter  Phases of Matter – read about change of state pg 3-4  Solid  Fixed volume and shape  Cannot be compressed  Closely packed, vibrate in place  Liquid  Fixed volume, no fixed shape  Cannot be compressed  Close together, but forces weaker than those in solids  Particles move around  Gas  No fixed volume or shape  Can be compressed  Partiles far apart, move around more than in liquids

Language of Chemistry (read TOK on page 7)  Chemical symbols – IUPAC (international union of pure and applied chemistry) monitors systematic naming of elements and compounds. No translation is needed from country to country.  Balanced chemical equations use arrows and phase labels ReactantsProducts 2 HCl (aq) + Mg (s) MgCl 2 (aq) + H 2 (g)

Common combinations of Elements  Ions are charged particles  Some ions are formed by neutral elements gaining or losing electrons (in very predictable patterns)  Some ions are polyatomic ions see Table 1 on pg 7.  Some elements are diatomic  N 2, O 2, F 2, Cl 2, Br 2, I 2, H 2  Others are Different as well  Common S 8, P 4

Monatomic ions  Look at bohr models  Atoms are stabalied full outer shell  Either cation: lose all outer electrons for full previous shell (+ ion)  OR anioin: gain enough electrons to fill current outer shell (- ion)

Balance Reactions  Mass should be equal before and after reaction.  Coefficients represent ratios of #s of particles (or moles of particles) NOT mass ratio Examples:  Chlorine gas reacts with solid calcium to produce solid calcium chloride.  Solid magnesium reacts with aqueous hydrochloric acid to form aqueous magnesium chloride and hydrogen gas.

Types of Reactions  Read about types of reaction on page 9  Practice problems in summer homework (part b)

Experimental empirical and molecular formla  Homework tonight:  Read page  Complete question 9 on page 35  Read lab for tomorrow