5.3. Salts and 5.4. Other ways of making salts

• Carbonate: A carbonate is a salt or ester of carbonic acid (H2CO3), containing the group CO3. Carbonates commonly occur in nature and are important minerals. Examples include calcium carbonate (CaCO3), found in limestone and chalk, and sodium carbonate (Na2CO3), known as washing soda.
• Chloride: A chloride is a compound formed by the chemical combination of chlorine with another element or group. Chlorides are abundant in nature and play essential roles in various chemical processes. Common examples include sodium chloride (NaCl), or table salt, and hydrochloric acid (HCl).
• Citrates: Citrates are salts or esters of citric acid (C6H8O7), a weak organic acid found in citrus fruits. Citrates have various applications, including as food additives, chelating agents, and pharmaceuticals.
• Crystallization: Crystallization is the process by which a solid forms, where atoms or molecules arrange themselves into a highly structured, periodic arrangement known as a crystal lattice. Crystallization occurs when a solution or a melt becomes supersaturated, causing solute particles to come together and form crystals.
• Formula (plural: formulae): In chemistry, a formula is a concise way of expressing the composition of a chemical compound using chemical symbols and numbers. It indicates the types and numbers of atoms present in a molecule. For example, the formula for water is H2O, indicating two hydrogen atoms bonded to one oxygen atom.
• Nitrate: A nitrate is a compound containing the nitrate ion (NO3-), which consists of one nitrogen atom bonded to three oxygen atoms. Nitrates are important in agriculture as fertilizers and in various industrial processes. Examples include potassium nitrate (KNO3) and ammonium nitrate (NH4NO3).
• Salt: In chemistry, a salt is a compound formed by the reaction of an acid with a base, where the hydrogen ion of the acid is replaced by a metal ion or another positive ion. Salts are typically composed of ions held together by ionic bonds. Common table salt (sodium chloride, NaCl) is a well-known example.
• Sulfate: A sulfate is a chemical compound containing the sulfate ion (SO4^2-), consisting of one sulfur atom bonded to four oxygen atoms. Sulfates are widespread in nature and have various industrial applications. Examples include sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4), known as Epsom salt.
• Hydrochloric Acid (HCl):

  • Formula: HCl
  • Example Salt: Sodium chloride (NaCl) - common table salt
• Sulfuric Acid (H2SO4):

  • Formula: H2SO4
  • Example Salt: Copper sulfate (CuSO4)
• Nitric Acid (HNO3):

  • Formula: HNO3
  • Example Salt: Potassium nitrate (KNO3)
• Carbonic Acid (H2CO3):

  • Formula: H2CO3
  • Example Salt: Sodium carbonate (Na2CO3) - used in making glass and soap
• Citric Acid (C6H8O7):

  • Formula: C6H8O7
  • Example Salt: Sodium citrate (Na3C6H5O7) - used as a food additive and in pharmaceuticals
• Reactions between acids and different kinds of bases result in neutralization reactions
• Metal oxides and hydroxides, when reacting with acids, form a salt and water
• Example: Hydrochloric acid + sodium oxide → Sodium chloride + water
• Example: Sulfuric acid + potassium hydroxide → Potassium sulfate + water
• Acids reacting with metal carbonates also form a salt, water, and carbon dioxide
• Example: Nitric acid + calcium carbonate → Calcium nitrate + water + carbon dioxide
• Soluble salts dissolve in water
• Steps to make a soluble salt using an insoluble base:

  • Place dilute acid (e.g. hydrochloric acid) in a beaker and gently heat it
  • Add insoluble base (e.g. copper oxide) gradually until some base no longer disappears, indicating excess base
  • Filter out excess base using filter paper and funnel
  • Evaporate off some water from the filtered solution to form solid crystals of the soluble salt (e.g. copper chloride)
  • Filter out the crystals and dry them
• pH scale measures how acidic or alkaline a solution is, ranging from 0 to 14
• Low numbers on the pH scale indicate acidity, high numbers indicate alkalinity, and a pH of 7 is neutral
• Examples of pH levels:

  • Stomach acid: pH around 2
  • Acid rain: pH around 4
  • Washing up liquid: pH around 9
  • Bleach: pH around 12
• pH can be measured using indicators or a pH probe connected to a pH meter
• Indicators are chemical dyes that change color based on pH, with different indicators changing color at different pH levels
• Universal indicator is a wide range indicator that changes color from deep red (acidic) to yellow, green, and bluey purple (alkaline)
• A pH probe connected to a pH meter provides a numerical reading, which is more accurate and precise than using indicators
• Acids are substances with a pH less than 7, release hydrogen ions in water, making the solution acidic
• Bases have a pH greater than 7, while alkalis are a subgroup of bases that are soluble in water
• Alkalis dissolve in water to form a solution with a pH greater than 7 and release hydroxide ions (OH-) in water
• Neutralization reaction occurs when an acid and a base react, producing a salt and water
• Example: Hydrochloric acid + Sodium hydroxide → Sodium chloride + Water
• In neutralization reactions, hydrogen ions (H+) from the acid and hydroxide ions (OH-) from the base combine to form water (H2O)
• Common acids: Hydrochloric acid, Sulfuric acid, Nitric acid
• Common bases: Hydroxides or carbonates like Sodium hydroxide, Calcium carbonate
• pH scale measures how acidic or alkaline a solution is, ranging from 0 to 14
• Low numbers on the pH scale indicate acidity, high numbers indicate alkalinity, and a pH of 7 is neutral
• Examples of pH levels:

  • Stomach acid: pH around 2
  • Acid rain: pH around 4
  • Washing up liquid: pH around 9
  • Bleach: pH around 12
• pH can be measured using indicators or a pH probe connected to a pH meter