Chemical formulae
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Ionic compounds are composed of positive and negative ions. Positive ions, called cations, include sodium (Na+) and ammonium (NH4+). Negative ions, called anions, include chloride (Cl-) and carbonate (CO32-). Chemical formulas represent the elemental composition and ratios of ions that make up ionic compounds.
Chemical formulae
- 1. CHEMICAL FORMULAE ¨C MOLECULAR FORMULA ? Ionic compounds are compounds made up of ions. ? Ions are atoms or groups of atoms with positive or negative charges on them. ? Positive ions are called cations. Examples include the sodium ion, Na+ and the ammonium ion, NH4 +. ? Negative ions are called anions. Examples include the chloride ion, CI- , and the carbonate ion, CO3 2 -.
- 11. CHEMICAL EQUATIONS - SOLUTIONS
- 12. CHEMICAL EQUATIONS ¨C PROBLEM SOLVING
- 13. CHEMICAL EQUATIONS ¨C PROBLEM SOLVING Solution: (a) 2 moles of Na react with 1 mole of CI2. 1 mole of Na will react with ?2 moles of Cl2 Hence 0.2 moles of Na will react with ?2 x 0.2 = 0.1 mole of Cl2. (b) Molar mass of Cl2 = 2 x 35.5 = 71 g mol- 1 Number of moles of Cl2=1.42/71 = 0.02 moles 1 mole of Cl2 reacts with 2 moles of Na, 0.02 moles of CI2 will react with 0.02 x 2 = 0.04 mole of Na. Therefore, mass of Na = 0.04 x Ar of Na = 0.04 x 23 = 0.92 g.