highschool/Grade 10/Science/SNC2DZ/Unit 1: Chemistry Part 2.md

Chemistry

Acids

• All acids contain hydrogen ions
• Behave like molecular compounds while out of water
• Behave like ionic compounds while aqueous
  • Hydrogen ions are released
  • Conduct electricity
• Reacts with active metals depending on the activity series as a single displacement reaction between the metal and the hydrogen ion
• Corrosive (reacts with skin)
• Sour-tasting

Naming Binary Acids

• \(`HCl_{(g)} \rightarrow`\) hydrogen chloride
• \(`HCl_{(aq)} \rightarrow`\) hydrofluoric acid
• Need to put the hydro prefix as it tells us its disolved in water and is an acid

Naming Oxyacids

• ite ions make ous acides (suffix). \(`HCLO_2 = `\) Chlorous acid
• ate ions make ic acides (suffix). \(`HCLO_3 = `\) Chloric acid
• Prefixes stay the same

Bases

• All bases contain hydroxide or carbonate ions
• Behave like molecular compounds while out of water
• Behave like ionic compounds while aqueous
  • Hydroxide ions are released
  • Conduct electricity
• Reacts with fats and oils to form soap
• Bitter-tasting

pH

• Used as a scale to measure how acidic or basic a substance is
• Presented as a scale from 0-14
• The lower the pH the more acidic, the higher the pH the more basic
• Measures concentration of hydrogen ions in solution
• pH scale is logarithmic
• Concentration is increased tenfold when pH is increased by 1
  • pH 1 = 0.1 mol/L
  • pH 14 = 0.00000000000001 mol/L
• Water at 25 degrees Celsius is pH 7.0 (neither acidic nor basic)

Chemical Change

• Similar to chemical reaction

Evidence of Chemical Change: (observations that tell us its happening)

1. A new gas is formed (new odour, formation of bubbles)
2. A large change in energy (eg. Light, heat, sound, electricity)
3. A new colour is formed
4. A new solid is formed

Representing Chemical Reactions

• A Chemical equation!
  • Used to model what is happening during a chemical reaction.
  • We use an arrow instead of an equal sign to show becomes, reacts to form, produces
  • On the left side, we always have the REACTANTS, (INPUT), these get used up in the chemical reaction
    • There can be plus signs to show multiple reactants. (Recipes, we are adding them together)
  • On the right side, we have the PRODUCTS (OUTPUT).
    • Newly produced/made from reactants
      
    • Plus signs show multple products, more like an AND more than anything else
• In a chemical reaction, reactant, molecules/atoms/formula units/ions reaarange to produce products moleccules/atoms/ions/formula units
• eg. Wax \(`+`\) oxygen gase \(`\rightarrow`\) Soot \(`+`\) Water \(`+`\) Carbon dioxide.
• A word equation
• \(`\triangle`\) Greek letter to represent heat.
• \(`C_{25}H_{52(g)} + O_{2(g)} \rightarrow^\triangle C_{(g)} + H_2O_{(g)} + CO_{2(g)}`\)

Types Of Reactions

• 6 types of reactions
  • synthesis
  • decomposition
  • single displacement
  • double displacement
  • combustion
  • neutralization

Sythensis

• When 2 or more substances combine into one substance
• \(`A + B \rightarrow AB`\)

Decomposition

• When a substance breaks down into 2 or more simpler substances
• \(`AB \rightarrow A + B`\)

Single Diplacement

• When an element displaces another of the same group in a substance
• \(`A + BC \rightarrow B + AC`\)

Double Displacement

• When two cations switch places in two substances
• \(`AB + CD \rightarrow CB + AD`\)
• Note: If both products would be aqueous, there is no reaction

Combustion

• Two types: Combustion with metals and combustion with hydrocarbons
• Combustion requires and releases heat but for the purposes of grade 10 chemistry this is ignored
• Combustion with metals
  • When a pure metal and oxygen gas react to produce the most common oxide
  • e.g., \(`2Mg + O_{2(g)} \rightarrow 2MgO_{2(s)}`\)
• Combustion with hydrocarbons
  • Two types: Complete and incomplete combustion
  • Complete combustion
    • When a hydrocarbon reacts with oxygen gas to produce water and carbon dioxide
    • Only works when enough oxygen is provided
    • Flame is blue
    • e.g., \(`CH_{4} + 2O_{2} \rightarrow 2H_{2}O + CO_{2}`\)
  • Incomplete combustion
    • When a hydrocarbon reacts with oxygen gas to produce water, carbon dioxide, carbon, and/or carbon monoxide
    • Lack of oxygen prevents complete combustion
    • No hydrogen can be left over
    • Flame is orange/yellow
    • e.g., \(`2CH_{4} + 3O_{2} \rightarrow 4H_{2}O + 2CO`\)

Neutralization

• When an acid and base react with each other
• Changes properties of both the acid and base so that they are no longer acidic nor basic
• Acids give their hydrogen ion to the base
• Looks similar to double displacement
• Always makes a salt and water
  • Note: Scientific definition of salt is any soluble ionic compound
• If carbonic acid (\(`H_{2}CO_{3}`\)) would be formed it instantly splits into water and carbon dioxide
  • This reaction occurs even if both products would be aqueous
  • If this reaction occurs the product is written as water and carbon dioxide
• \(`H(A) + B(OH) \rightarrow AB + H_{2}O`\) or \(`H(A) + B(CO_{3}) \rightarrow AB + H_{2}O + CO_{2}`\)
• e.g., \(`HCl_{(aq)} + NaOH_{(aq)} \rightarrow NaCl_{(aq)} + H_{2}O`\)

Properties Of Acids and Bases

Property	Acids	Bases
Ion present in solution	Hydrogen, \(`H^+`\)	Hydroxide, \(`OH^-`\)
Reactivity with metals	Reactive	Reactive
Electric conductivity	Conductive	Conductive
Taste	Sour	Bitter
pH range	\(`[0, 7)`\)	\(`(7, 14]`\)
Chemical indicators:	Will turn red with blue litmus paper	Turns pink with phenolphthalein. Turns blue with red litmus paper