Chemistry of baking

Pure substances

made up of one element or are compounds). Substance has exact (properties) melting/boiling point, and that in the substance there is no 'contamination'.

Element

neutral substance that cannot be broken down into simpler substances using chemical methods.

contain a fixed number of protons, although different # of neutrons can be present (isotopes)

Compound

pure substance that formed when 2 or more elements combine together in fixed whole number ratios and cannot be broken down with physical means

Mixture

A physical combination of pure substances

Homogenous mixture

All components of mixutres are in the same phase (solid, liquid, etc), and uniform composition

Heterogeneous mixture

Non-uniform composition (seperating line/phase boundary), some components in different phases

Emulsion

System consisting of two immiscible liquids, one of which is dispersed in the other in

the form of small droplets

fractional distillation

a mixture of liquids is separated into its components by successive vaporizations and condensations in a vertical fractionating column. Used for close boiling points

Simple distillation

Heating the mixture to vaporize the most volatile component. Used for significant differences in the boiling points.

Seperation funnel

Used to separate immiscible liquids solvents based on their different phases

immiscible liquids

substances that do not mix or dissolve into each other forming distinct layers

Chromotography

Chromatography is a technique used to separate and identify components of a mixture based on their different affinities for a stationary phase and a mobile phase. Substances that interact more strongly with the stationary phase move more slowly, while those that interact less move faster, allowing the mixture to be separated. Chromatography can be used for qualitative analysis (identifying substances) and, in some cases, quantitative analysis (measuring amounts).

gel electrophoresis

Gel electrophoresis works by separating molecules based on size and charge. Molecules move through a gel matrix toward an electrode, with smaller or more strongly charged molecules moving faster, causing them to separate.

Solid

Particles are tightly packed and vibrate in place, giving a fixed shape and volume.

liquid

Particles are close but can move past each other, giving a fixed volume but no fixed shape

Gas

Gas is a state of matter in which particles are widely spaced, move freely, and have no fixed shape or volume. Gases expand to fill their container and can be compressed. Their behavior is described by pressure, volume, temperature, and the number of particles.

Vaporization

Process where a liquid turns into a gas when particles gain enough energy to overcome intermolecular forces.

Evaporation

Particles at the surface of liquid gain enough energy to overcome intermolecular forces, slow rate of reaction and at below boiling point.

Boiling

Particles throughout the liquid gain enough energy to overcome intermolecular forces at a set boiling point and much faster rate of reaction. Endothermic and water remains at constant temperature.

Condensation

Gas to liquid (exothermic)

sublimation

solid to gas (endothermic)

deposition

gas to liquid (exothermic)

Atomic mass

Number of Nucleons (protons plus neutrons)

phase change, what happens to the energy?

no change in EK as the temp remains constant, the change in energy is an increase in potential energy (energy stores in the bonds, and it is increasing so much that is caused their 'potential' to allow motion to change) due to the change in intermolecular forces between the particles.

molecular mass

Sum of all atomic mass of a molecules constituent elements

relative atomic mass (Ar)

Weighted average of an atom’s natural abundance of isotopes compared to the mass of 1/12 of a carbon 12th atom

empirical formula

smallest whole # ratio of atoms of each element in a compound

mole

1/12 of the number of particles in carbon-12

Hess's Law

If a substance or substances (A) is converted to another substance or substances (B) in a single step or in multiple steps (C, D, etc), the total energy change is the same regardless of the route.

Manufacturer's accuracy

Guaranteed level of accuracy of performance specified by the equipment. It tells us how close the instruments readings are to the true value when utilized under standard conditions.

Measurement uncertainty

the range of possible error in a specific measurement.

Net ionic equations

Removes all the spectator ions (ions that are the same charge and appear the same in both sides of the reactino)

Thermal decomposition

The breaking up of a chemical substance with heat into at least two chemical substance ( endothermic)

Neutralisation reaction

The reaction of an acid and a base forming a salt (containing the anion of the acid and the cation of the base) (exothermic)

Single displacement reactions

Where the more reactive element is able to replace, displace or replace the less reactive element from its compound AB+C→AC+B

Double displacement reactions

AB+CD→AD+CB

Combustion reaction

Fuel is ignited in the presence of oxygen creating H₂O, CO₂ and heat (exothermic)

Temperature

Average kinetic energy of particles

Heat

he transfer of thermal energy between systems or objects due to a temperature difference, flowing from hot to cold until thermal equilibrium is reached, measured in Joules

1st law of thermodynamics

The principle of conservation of energy. Energy can be transferred and transformed, but it cannot be created or destroyed.

Enthalpy change (∆H)

Enthalpy change is the heat energy change that occurs during a chemical reaction at constant pressure. It can be exothermic, releasing energy to the surroundings (negative ΔH), or endothermic, absorbing energy from the surroundings (positive ΔH).

Internal energy

Sum of kinetic and potential energy of a substance

Enthalpy change formula

∆H = Enthalpy change of products - Enthalpy change of reactants

saturated

When a solvent has dissolved the maxium amount of solute it cna dissolve meaning it cannot dissolve any mroe solute

precipitate

Solid formed in a solution

solubility

How much solute can be dissolved in given solvent at a given temperature

concentration

moles contained over volume

Molality

Number of moles in a solution per kilogram of solvent

Atom economy

A measure of the amount of starting materials that end up as useful products.

(mass of wanted products/ total mass of reactants) x 100= %

exothermic reaction

Heat is released to the surroundings, ∆H is negative, the energy is stored in the products is less than in the reactants, reactants is more stable than products. (Neutralization and combustion)

Endothermic reaction

Heat absorbs from the surroundings in the form of heat, ∆H is positive, energy in products is more than energy in reactants, products are less stable (melting evaporation)

activation energy (Ea)

the minimum amount of energy that must be supplied to start a chemical reaction

factors that cause experimental yield to be lower than theoretical yield

Incomplete reactions: Some reactants may not fully react.

Loss of product during transfer or filtration: Some material can stick to equipment or be lost in handling.

Side reactions: Formation of unwanted by-products reduces the amount of desired product.

Purification losses: Crystallization, drying, or other purification steps may remove some product.

Volatile products: Some products may evaporate during the experiment.

factors that cause experimental yield to be higher than theoretical yield

1. impurities in product
2. product not fully 'dried'
3. incomplete reaction

crystal

which refers to the solid material with a repeating pattern of particles, including the water molecules in hydrated compounds

volatility