Stoichiometry PDF

Formula of ionic compounds Metals - positive charge ions Nonmetals - negative charge ions Group 1 - K+ , Na+ 11- Ca2+ , Mg2+ 111- Al3+ Transition metals Zn2+, Cu+, Cu2+, Ag+, Fe2+, Fe3+, Cr3+ Polyatomic ions Carbon atom carbide ion carbonate ion C...

Formula of ionic compounds Metals - positive charge ions Nonmetals - negative charge ions Group 1 - K+ , Na+ 11- Ca2+ , Mg2+ 111- Al3+ Transition metals Zn2+, Cu+, Cu2+, Ag+, Fe2+, Fe3+, Cr3+ Polyatomic ions Carbon atom carbide ion carbonate ion C C4+/4- CO32- Nitrogen atom nitride ion nitrate ion N N3- NO3- ammonium ion NH + Oxygen atom oxide ion hydroxide ion O O2- OH- Sulfur atom sulfide ion sulfate ion S S2- SO42- Formulae of simple/complex ionic compounds Definition of molecular formula of a compound - is the number and type of different atoms in one molecule. Empirical formula of a compound - is the simplest whole number ratio The different atoms/ions in a compound  Writing Equations Write equations for the following reactions 1) Zinc reacts with hydrochloric acid to form zinc(II) chloride and hydrogen. 2) On heating what does sodium nitrate decomposes to. Sodium nitrite and oxygen. Nitrite ion NO2- 3) Sulphur dioxide burns in air to form sulfur trioxide. Examples 1) Zn + 2 HCl ZnCl2 + H2 Zinc reacts with hydrochloric acid. 2) 2NaNO3 2 NaNO2 + O2 Sodium nitrate decomposes on heating. 3) 2SO2 + O2 2 SO3 Sulfur dioxide burns in air. Definitions Relative atomic mass(Ar) is average mass of isotopes of an element compared to 1/12th of the mass of carbon atom. Relative molecular mass(Mr) is the sum of relative atomic masses of covalent compounds. Relative formula mass(Mr) is used for ionic compounds REACTING MASS CALCULATIONS (Example 1) 1) What mass of oxygen reacts with 12 g of magnesium? ✓ ? 2Mg + O2 → 2MgO Moles Mg = mass = 12 Mr Moles of O2 = 0.25 24 = 0.5 Mg : O2 Mass of O2 = Mr x 2 : 1 moles 0.5 : ? = 32 x  MOLE LO Define the mole and the Avogadro constant 1 mole = 6.02 x 10 23 atoms/particles/molecules H2(g)1 mole = 2g = 24dm3 =6.02 x 1023 atoms NaCl(s)1mole = 58.5g = 6.02 x 1023 particles Both of these videos are a great intro to moles - could set as prior learning perhaps. Both of these videos are a great support for weaker students struggling with converting Between moles, atoms, and molecules This video is a great support for weaker students struggling with working out Mr. Note for students: parentheses = brackets! Why would it be difficult to measure the moles of gas using this equation? n = V  Key Knowledge 1 mole of any gas occupies 24 dm3 at room temperature (25ºC) and pressure (1 atm) Example 1) Calculate the volume of hydrogen gas liberated when 2.4g of magnesium reacts with excess dilute hydrochloric acid? Mg + 2 HCl ------------> MgCl 2 + H2 Step 1 - calculate the moles of Mg used n = mass Step 3 - Change moles to volume Mr n = vol 24dm3 = 2.4 0.1 = Vol 24 24dm3 = 0.1 0.1 x 24 = Vol Step 2 - ratio Mg to H2 Vol = 2.4dm3 or 2400cm3 1:1 2. 1/6 15.3g 1/3 x 24 = Vol 8 dm3 = Vol  32g of Sulfur combines with 32g of Oxygen to form an oxide of Sulfur. Calculate the empirical formula Elements that combine Sulfur Oxygen Masses that combine 32 32 Relative atomic mass (Ar) 32 16 Moles of atoms that combine 32/32 = 1 32/16 = 2 Divide the smallest number 1/1 = 1 2/1 = 2 Ratio in which atoms combine 1:2 Empirical formula SO2  Percentage yield However, it is rare in a real life to produce the theoretical mass. The actual mass produced in real life compared to the theoretical mass is called the percentage yield. Theoretical yield 0.47 g Actual yield 0.42 g Percentage yield ?