Miscibility, Solutions, and Chemical reactions

Flashcards covering mixtures, solubility, emulsifiers, ionic solutions, precipitation reactions, and the chemistry of soaps and hard water.

How are solvents categorized based on polarity, and what are examples of each?

Solvents are categorized as polar (e.g., water, methanol) or non-polar (e.g., Hexane, turpentine, petrol).

According to the notes, how does molecular size affect the solubility of substances in water?

Molecular substances with small molecules are more soluble in water than larger molecules of similar polarity.

Why do ethanol and water mix freely at a molecular level?

Because the attractions between their molecules are similar ($Hydrogen-bonds$), allowing each substance to disperse into the other.

Why do hexane and water fail to mix?

The attractions between water ($Hydrogen-bonds$) and hexane ($London-forces$) are different, making the mixing cause significant disruption to the liquid structure, keeping them in an unmixed state.

What is the function of an emulsifier in a mixture?

An emulsifier contains both polar and non-polar components to hold two opposite components together and prevent separation.

In the context of food chemistry, how does an egg act as an emulsifier in mayonnaise?

The egg holds the polar vinegar component and the non-polar oil component together in a creamy consistency.

What are three examples of emulsifiers used in cosmetics?

Polysorbates, laureth-4, and potassium cetyl sulfate.

Explain the movement of paraffin in a lava lamp using density and temperature.

The nonpolar paraffin mixture is heated by a coil, becomes less dense, and moves up; at the top, it cools, becomes denser, and descends.

What specific interaction occurs when an ionic substance like $NaCl$ dissolves in water?

Ion-dipole interactions form between the charged ions ($Na^+$ and $Cl^-$) and the polar water molecules.

According to the solubility rules provided, which types of salts are always soluble?

All Group 1 salts, all ammonium salts, and all nitrate salts.

What is the chemical equation for the precipitation reaction between potassium iodide and lead nitrate?

$$2KI(aq) + Pb(NO_3)_2(aq) \rightarrow PbI_2(s) + 2KNO_3(aq)$$

What is the definition of a precipitate?

An insoluble substance that forms during a chemical reaction between two solutions.

What is the ionic equation for the reaction between Silver nitrate and sodium chloride?

$$Ag^+(aq) + Cl^-(aq) \rightarrow AgCl(s)$$

Describe the dual nature of a soap molecule's structure.

It consists of a long non-polar covalent hydrocarbon 'tail' (hydrophobic) and a polar, ionic 'head' (hydrophilic).

What are 'micelles' in the context of soap action?

Droplets of grease broken up and held in suspension in water by the repulsion of the negatively charged ionic heads of soap molecules.

What is 'hard water' and why does it cause soap scum?

Hard water contains $Mg^{2+}$ and $Ca^{2+}$ ions which react with soap to form insoluble salts like $(C_{17}H_{33}COO^-)_2Ca^{2+}$.

What is the difference between temporary and permanent hard water?

Temporary hard water is due to dissolved calcium bicarbonate and can be removed by boiling; permanent hardness is due to calcium and magnesium sulfates and cannot be boiled away.

How is limescale chemically formed from temporary hard water?

Calcium bicarbonate decomposes when heated: $Ca(HCO_3)_2(aq) \rightarrow CaCO_3(s) + CO_2(aq) + H_2O(l)$

How can limescale be removed from surfaces?

By reacting it with an acid (such as lactic, sulfamic, phosphoric, or hydrochloric acid) to produce a soluble calcium salt, carbon dioxide, and water.

How do the pH levels of traditional soap and body wash compare?

Soap is alkaline with a $pH$ of $8.0$-$11.0$, while body wash has a $pH$ of $4.0$-$6.0$, which is closer to the skin's natural $pH$ of $4.5$-$5.5$.

What base is used to create solid soaps versus liquid soaps?

Sodium hydroxide ($NaOH$) creates solid soaps, while potassium hydroxide ($KOH$) creates liquid soaps.