CHEM125 – CHAPTER 04 – BASIC HOMEWORK

Nonmetals don’t conduct electricity; most like to form negative ions. All metals conduct electricity. (The valence electrons which can move throughout the metal conduct the electricity.) In reactions, metals like to lose electrons and form positive ions. The alkali metals are the most reactive group of metals. They are so reactive that they react with cold water to produce the hydroxide ion and hydrogen gas. The alkaline earth metals are the next most reactive group. Most of them also react with cold water to produce the hydroxide ion and hydrogen gas. For example, 2Li(s) + 2H₂O(l) –> 2Li⁺(aq) + 2OH^–(aq) +H₂(g) Many metals are reactive enough to react with acid to produce hydrogen, such as Al, Cr, and Fe. For example, 2Fe(s) + 6H⁺(aq) –> 2Fe³⁺(aq) + 3H₂(g) A few metals are so inert that they won’t react with acid or even oxygen, such as Ag, Au, and Pt.

Metals and nonmetals combine to make ionic compounds. The metal exists as a positive ion and the nonmetal as a negative ion. The ionic compounds are held together by strong electrostatic forces between the negative and positive ions and exist in the solid state. Because of these strong attractive forces, ionic compounds in the solid state do not conduct electricity. In the liquid or molten state, the ions are free to move. The movement of ions causes them to conduct electricity. Many ionic compounds dissolve in water and the process of dissolution separates the ions, making them free to move and conduct electricity. Compounds aren’t 100% ionic. The greater the difference in electronegativity the more ionic the compound. Electronegativity is a measure of how much an element wants an additional electron or electrons. The more to the right and the more to the top in the periodic table the greater the electronegativity. F is the most electronegative. The more to the left and down in the periodic table the smaller the electronegativity. Cs has the smallest electronegativity of the non-radioactive elements.

Ionic compounds also consist of a positive metal ion and a polyatomic negative ion. For example, the phosphate ion (PO₄^3-) is a polyatomic ion and FePO₄ is an ionic compound.

Fully dissolves in water

Fully dissolves in water

Does not dissolve in water

Fully dissolves in water

Partially dissolves in water

molarity=mol/L= 0.46 mol NaCl/4.0L = 0.115 M

0.25 mol/ 3 L = 0.0833 M 1 mol of Al3+ in Al(NO3)3 —> 0.0833 Al3+ M

0.61 mol Ba(NO3)2/ 5 L = 0.122 molarity 2 mols of NO3 in each mol Ba(NO3)2 0.122 M (2) = 0.244 M

1.47 g Ca(OH)2/ (74.093 g/mol Ca(OH)2) = 0.01984 mol Ca(OH)2 0.01984 mol Ca(OH)2 / 3L = 0.00661331 M Ca(OH)2

443 mL = 0.443 L 0.33 mol HNO3/ L * 0.443 L = 0.14619 mol HNO3 0.14619 mol H+ (1:1 ration of H+:HNO3)

0.430 L * 0.82 mol NaOH/L = 0.3526 mol NaOH 0.3526 mol OH- (1:1 ration OH-: NaOH)

0.10 mol FeCl3 / 1L * 0.369 L = 0.0369 FeCl3 3(0.0369) = 0.1107 mol Cl- (3:1 ration Cl: FeCl3)

Insoluble product/compound = precipitate Hint: It obviously cannot be an ion because if it was an ion that would mean it had the viability to dissociate and is therefore soluble

Spectator ions are not involved in the precipitate or the main reaction and are typically part of a soluble compound in the product.

Spectator ions are not included in tenet ionic equation as they appear as themselves in both the products and reactants. While the other ions may appear as ions on one side but as a compound on the other.

HCl + Li(OH) –> H2O (l) + LiCl (aq) H+ + Cl- + Li+ + OH- –> H2O + Li+ + Cl-