Matter Types…And Changes

CHM 1010 PGCC Barbara A. Gage

Matter Mixture – material with two or more components with variable composition Solution – material with two or more components homogeneously mixed; can have variable proportions of the components Pure substance – material with a constant chemical composition

Physical Separation Techniques What property is each technique based on? Dissolving Evaporating (evaporation) Filtering (filtration) Chromatography Sieving sifting straining Subliming (sublimation) Distilling (distillation) Extracting (extraction)

CHM 1010 PGCC Barbara A. Gage

Types of Matter Element - the simplest type of substance with unique physical and chemical properties. It cannot be broken down into any simpler substances by physical or chemical means. Compound - a substance composed of two or more elements which are chemically combined.

Allowed to react chemically therefore cannot be separated by physical means. Figure 2.19 Silberberg The distinction between mixtures and compounds. S Fe Physically mixed therefore can be separated by physical means; in this case by a magnet.

CHM 1010 PGCC Barbara A. Gage

Types of Matter Atom – smallest unit of an element with all the characteristics of the element

Types of Matter Molecule - a structure that consists of two or more atoms that are chemically bound together and thus behaves as an independent unit; smallest characteristic unit of a compound that retains the properties of the compound Figure 2.1 Silberberg

The boxes here contain submicroscopic views of particles. Indicate which box(es) contain the stated item(s) and why. a.only elements b.one compound c.mixture of compounds d.molecules a.B, C, E b.A (plus an element), D c.F d.All but E

Element Names and Symbols Each element has a name and 1, 2 or 3 letter abbreviation called a symbol. The first letter in a symbol MUST be capital and the other(s) lowercase. hydrogen Hhelium He carbon C cobalt Co sodium Napotassium K lead Pbmercury Hg Image from WebElements

Element Names and Symbols Number of elements – 117 (#117 has not been identified but 118 has) CHM 1010 PGCC Barbara A. Gage

Chemical Formulas Some elements appear in nature bonded to each other. These are referred to as diatomic or polyatomic molecules. H 2, O 2, N 2, F 2, Cl 2, Br 2, I 2 C 60, S 8, P 4 The 2 in O 2 is termed a subscript and refers to the element immediately in front of it.

Chemical Formulas CO 2 contains 1 atom of carbon and two atoms of oxygen all chemically linked. H 2 SO 4 contains 2 hydrogen, 1 sulfur, and 4 oxygen atoms. (NH 4 ) 2 C 2 O 4 - A subscript outside parentheses applies to everything within the parentheses; 2 N, 8 H, 2 C, 4 O

Chemical Formulas How many atoms of each type are in the following compounds? K 2 CO 3 Ca 3 (PO 4 ) 2 C 6 H 4 COOHCOC 2 H 5 AlK(SO 4 ) 2. 12H 2 O

Chemical Reaction Chemical change = chemical reaction Changes may be visible: color change cloudiness (precipitation) gas formed (bubbles and/or odor) reactant decreases (without dissolving) energy is released or absorbed

Chemical Equations Chemical changes can be written symbolically. The symbolic representation is called a chemical equation. Carbon reacts with oxygen to form carbon dioxide. C + O 2  CO 2 reactantsproducts

Chemical Equations Reaction arrows can go in either direction: 2 H 2 + O 2  2 H 2 O Or both directions: NH 4 OH  NH 3 + H 2 O

Or…

Chemical Equations Because of the Law of Conservation of Matter, you must account for all atoms in a chemical change. Carbon reacts with oxygen to form carbon monoxide. C + O 2  CO 2 C + O 2  2 CO coefficient Equation is now balanced.

Chemical Equations A sample of propane, C 3 H 8, when ignited with oxygen produces carbon dioxide and water. C 3 H 8 + O 2  CO 2 + H 2 O C 3 H O 2  3 CO H 2 O

Chemical Equations Balance the following: CaCl 2 + Na 2 CO 3  NaCl + CaCO 3 C 3 H 8 O 2 + O 2  CO 2 + H 2 O H 2 SO 4 + KOH  K 2 SO 4 + H 2 O

Chemical Equations If you have information on the states of matter, that can be added to the equation. s = solid l = liquid g = gas aq = aqueous Aqueous silver nitrate reacts with aqueous potassium chloride to form solid silver chloride and aqueous potassium nitrate. AgNO 3 (aq) + KCl (aq)  AgCl (s) + KNO 3 (aq)

Write the balanced chemical equation for the change in the boxes. Before After

Balancing Tips… Balance polyatomic ions (units) that stay intact as a single unit. Leave hydrogens and oxygens to the last (oxygen very last). Be sure to reduce the coefficients to the smallest whole numbers.

Types of Reactions 1) Combination or Synthesis elements or (element + compound) or compounds------> compound Fe (s) + S (s) >FeS (s) O 2 (g) + 2 CO (g) > 2 CO 2 (g) H 2 O (l) + SO 3 (g) > H 2 SO 4 (aq)

Types of Reactions 2)Decomposition or Analysis compound > elements or (element and compound) or compounds 2 HgO (s) -----> 2Hg (l) + O 2 (g) 2 KBrO 3 (s) -----> 2 KBr (s) + 3 O 2 (g) CaCO 3 (s) > CaO (s) + CO 2 (g)

Types of Reactions 3)Single Replacement element + compound > element + compound Cu (s) + 2AgNO 3 (aq) ----> 2Ag (s) + Cu(NO 3 ) 2 (aq)

Types of Reactions 4)Double Replacement compound + compound —> compound +compound AgNO 3 (aq) + NaCl (aq) —> AgCl (s) +NaNO 3 (aq) Double Replacement Rxns: Solid forming AgNO 3 (aq) + NaCl (aq) —> AgCl (s) +NaNO 3 (aq) Gas-forming KHCO 3 (aq) + HCl (aq) ----> KCl (aq) + CO 2 (g) +H 2 O (l) Acid-Base HCl (aq) + KOH (aq) ----> KCl (aq) + H 2 O (l)

Types of Reactions 5)Oxidation-Reduction (redox) CH 4 (g) + 2O 2 (g) ----> CO 2 (g) + 2H 2 O (l) 2Mg (s) + O 2 (g) > 2MgO (s) 4HCl (aq) + 3FeCl 2 (aq) + KMnO 4 (aq) --> MnO 2 (s) + KCl(aq) + 3FeCl 3 (aq) + 2H 2 O(l)

Investigation of Chemical Reactions Let’s finish the lab by writing the balanced chemical equations and determining the reaction types: 1.Mg + HCl 2.Mg (heat) 3.CoCl 2 + Na 3 PO 4 4.Fe + CuSO 4 5.KClO 3 (heat) 6.CuCO 3 (heat)