Acids, Bases & the pH Scale Nomenclature + Naming + Neutralizaton Acids, Bases & the pH Scale

What are Acids + Bases? These are created when substances are mixed with water. Acids: Release hydrogen ions - H+ ions into water. Bases: Release hydroxide - (OH)- ions into water. BOTH substances are corrosive, meaning they can give you a chemical burn.

Acids Acids will have the element hydrogen (H) first in their formula. E.G. HCl or H2SO4 Examples of acids at home: E.G. Vinegar, Lemon Juice, Coke or Pepsi and batteries. There are two types of acids: Oxyacids: Have oxygen in their formulas. Non-oxy acids: Don’t have oxygen in their formulas.

Naming Oxyacids Oxyacids: Have oxygen in their formulas. Q: What would you name H2(SO4) using the rules you know? A: Hydrogen Sulphate Rules for naming this acid: Drop “hydrogen” from the name “ate” ending  “ic acid” “ite” ending  “ous acids” What would the name of this acid H2(SO4) be? Sulphuric Acid

Naming Non-oxy acids: Non-oxy acids: Don’t have oxygen in their formulas. Q: What would you name HCl using the rules you know? A: Hydrogen Chloride Rules for naming this acid: Hydrogen  “Hydro” “ide” ending  “ic acid” What would the name of this acid HCl be? Hydrochloric Acid

Getting the Formulas for Acids This is the same as before  we use the “X-over rule”. What would the formula be for Hydrophosphoric acid? First write down the chemical symbols for each element or poly. ion + their charge: X-Over the charges to get the formula: H+ P3- H3 P

Properties of Acids Sour tasting Stings to touch Corrosive Water soluble React with metals Conduct electricity

Uses of Acids Fruit, drinks (coke, juice), yogurt, vinegar Batteries Catalyst Sore muscles

Bases Bases will have the hydroxide (OH-) group second in their formula. E.G. K(OH) or Na(OH) Examples of bases at home: E.G. Bleach, Dishsoap, Antacid tablets, Gaviscon or Draincleaner

Bases – Formulas + Naming The rules for naming bases is the same as before: The metal name stays the same and so does the name of the polyatomic ion (hydroxide). What would KOH and NaOH be called? To get the formulas we use the “X-Over rule”. What would the formula be for Lithium Hydroxide? Potassium Hydroxide Sodium Hydroxide Li(OH)

Properties of Bases Bitter to taste Slippery to touch Corrosive Water soluble Reactive Conductive

Safety Both corrosive Acids must be added to water for diluting Bases react with protein – can cause blindness!

The pH Scale The strength of acids and bases can be compared using a pH scale ACIDS NEUTRAL BASES  More acidic More  basic

The pH Scale In science we use the pH scale to determine if a substance is an acid, base or neutral (neither an acid or base) substance. ACIDS: Have a pH from o- 6.9 NEUTRAL: Have a pH of 7.0 BASES: Have a pH from 7.1-14

The pH Scale Q: Which is more acidic Apple or lemon juice? Q: Which is more basic Baking Soda or Ammonia? As you move farther away from the middle of the scale (Neutral pH=7) the substance becomes a stronger acid or base.

Indicators: Is it an Acid or Base? Q: What if the pH or formula isn’t given to you, how can you tell if it’s an acid, neutral or base? A: By using indicators. Indicators are substances that change colours when they contact an acid, base or neutral. We can observe the colour change of the indicator to determine if it’s an acid, base or neutral.

DEMOs Pop Rocks + Water with Bromothymol blue indicator. Water + Breath with Bromothymol Blue Comparing Indicators in Acid, Base + Neutral Substances

Neutralization Reactions This is a chemical reaction where an acid is added to a base or vice-versa. The end product is a neutral substance EQUATION: Acid + Base  Water + Salt (Ionic Compound) Q: What would you add (acid, base or nothing) to neutralize the pH? A. pH= 2 B. pH=9 C. pH=7

Neutralization Reactions Q: What would you add (acid, base or nothing) to neutralize the pH? A. pH= 2 B. pH=9 C. pH=7 A: A. Base B. Acid C. Nothing DEMO: Water + Acid or Base with Universal Indicator