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
Corrosive (reacts with skin)
Sour-tasting

\(`HCl_{(g)} \rightarrow`\) 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

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

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)

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.
\(`C_{25}H_{52(g)} + O_{2(g)} \rightarrow^\triangle C_{(g)} + H_2O_{(g)} + CO_{2(g)}`\)

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., \(`2CH_{4} + 3O_{2} \rightarrow 4H_{2}O + 2CO`\)

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., \(`HCl_{(aq)} + NaOH_{(aq)} \rightarrow NaCl_{(aq)} + H_{2}O`\)