Solutions, Acids, Bases & pH. Solute –substance whose particles are dissolved in a solution e.g. salt, sugar Solvent – the substance in which the solute dissolves e.g. water “universal solvent”. Dispersion of Sugar in Water. Properties of Liquid Substances.
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Solute –substance whose particles are dissolved in a solution e.g. salt, sugar Solvent – the substance in which the solute dissolves e.g. water “universal solvent”
Properties of Liquid Substances • Conductivity – ability to conduct electricity • Freezing point – decreases • Boiling point – increases • Heat of solution – energy is absorbed or released during the formation of a solution • Energy released = exothermic • Energy absorbed = endothermic
Electrolyte A substance that ionizes when dissolved in water • Conducts electricity
Factors Affecting Dissolving Rate • Surface area – ↑ surface area = ↑ rate • Stirring – moves dissolved particles away from the solid • Temperature – ↑ temperature = ↑ rate
One of the most important aspects of a living system is the degree of acidity or alkalinity
Ionization of water -breaking apart water molecules into ions Water is both an acid and a base • HOH + HOHH3O+ + OH- • (water)(water) (hydronium) (hydroxide)
Acid – compound that produces hydronium ions (H3O+) when dissolved in water
Acids • Characteristics of Acids • Tastes sour • Reacts strongly with metals • Conducts electricity in water • Turns blue litmus paper red • Generally clear solutions • Proton donors (give H+) Examples of Acids Vinegar H2SO4 Citrus fruits HNO3 Stomach acid HCl
Acetic acid CH3COOH Vinegar Carbonic acid H2CO3 Carbonated beverages Hydrochloric acid HCI Digestive juices in stomach Nitric acid HNO3 Fertilizer production Phosphoric acid H3PO4 Fertilizer production Sulfuric acid H2SO4 Car batteries
Add Base to Water OH- Na+ Na+ OH- OH- Na+ Na+ OH- Na+ OH- Na+ OH- OH- Na+ Na+ OH- NaOH Na+ + OH- Base – ionic compound that produces hydroxide ions (OH-) when dissolved in water
Bases • Characteristics of Bases • Tastes bitter • Reacts strongly with metals • Conducts electricity in water • Turns red litmus paper blue • Generally slippery feel • Proton acceptors (take H+) Examples of Bases Lye - NaOH Ammonia - NH3 Bleach (Hypochlorite)
Aluminum hydroxide Al(OH)3 Deodorant, antacid Calcium hydroxide Ca(OH)2 Concrete, plaster Magnesium hydroxide Mg(OH)2 Antacid, laxative Sodium hydroxide NaOH Drain cleaner, soap production
Neutralization Reaction between an Acid & Base that forms salt & water HCl + NaOH HOH + NaCl (Hydrochloric Acid) + (Sodium Hydroxide) (Water) + (Salt)
Sodium chloride NaCl Food flavoring, preservative Sodium carbonate Na2CO3 Used to make glass Potassium chloride KCl Used as a salt substitute to reduce dietary intake of sodium Potassium iodide Kl Added to table salt to prevent iodine deficiency Magnesium chloride MgCl2 De-icer for roads Calcium carbonate CaCO3 Chalk, marble floors, and tables Ammonium nitrate NH4NO3 Fertilizer, cold packs
Remember!! During a chemical reaction: • Bonds are broken • Elements are rearranged • New compounds are formed Balanced Equation - # of atoms of each element are equal on both sides of a chemical equation Reactants are shown on the left Products are shown on the right HCl + NaOH H2O + NaCl Reactants Products
pH Scale Measure of hydronium (H3O+) ion concentration • pH affects the physical & chemical properties of a substance
Acid – pH = 0-6 Neutral – pH = 7 Base – pH = 8-14
A change of one pH unit changes the H+ concentration by a factor of 10. A change of 1 pH unit changes the H3O+ concentration by a factor of 10 ie. pH 1 has 10x more hydronium ions than pH 2; 100x more than pH 3, etc.
How Many Times . . . stronger is pH 3 than pH 4? • 1 jump DOWN the scale • 1 x 10 • 10x MORE H3O+ ions! stronger is pH 5 than pH 8? • 3 jumps DOWN the scale • 10 x 10 x 10 • 1,000x MORE H3O+ ions! weaker is pH 12 than pH 7? • 5 jumps UP the scale • 10 x 10 x 10 x 10 x 10 • 100,000x LESS H3O+ ions! (but a strong base)
Indicator • Changes color as the pH changes • Indicates the pH of the solution
Buffer A solution that is resistant to large changes in pH • An acid or base with salt • Neutralizes small amounts of acids & bases • Necessary to maintain pH of body fluids at normal & safe levels
Works Cited www.chem4kids.com www.pasco.com faculty.fmcc.suny.edu creekconnections.allegheny.edu www.lcesc.k12.oh.us www.tennislifemagazine.com Physical Science Concepts In Action Textbook