Chemistry

Alcohols

Alcohols are organic compounds with an –OH group attached to them, which is their functional group. Like alkanes, alkenes, and alkynes, they form a homologous series, too! (Methanol, ethanol, propanol, butanol, etc.)

When naming alcohols with just an OH group, we replace the end “e” with an “ol” (Methane → MethanOL, etc.) For naming more complex alcohols, refer to previous topics.

The general formula for these guys is CnH2n+1OH.

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Remember, the –OH always goes at the end of each formula.

Making Alcohols:

Fermentation: The good, old-fashioned, and environmentally-friendly way to make alcohol. This process involves breaking down glucose without the presence of oxygen, which gives rise to alcohol, CO2, and ATP, as you would’ve studied in biology.

For this, natural sugar sources are used, such as grapes for red wine, and barley for beer. This process takes an extremely long time, but can be sped up with the catalyst of yeast, a natural fungus that feeds on sugar and produces carbon dioxide. This is also why bread has holes– they come from the carbon dioxide bubbles that burst during baking!.

It can also be done at temperatures as low as 37 degrees Celsius, and since plant sugars are a renewable resource, it’s good for the environment! However, it forms the waste product of carbon dioxide.

Hydration of Ethene: This one’s a different route with a similar ending. Ethene is an alkene extracted from the cracking of crude oil. Crude oil is a non-renewable resource, so this way isn’t exactly sustainable.

Ethene undergoes an addition reaction with water as steam (hydration) and phosphoric acid as a catalyst, forming just ethanol with no waste products! However, it has to be heated to extremely high temperatures to do this, making it a costly and difficult process.

Physical Properties

High Boiling Point: Alcohols have a high boiling point due to the hydrogen bonds formed between molecules thanks to the –OH group.

Chemical Properties

Flammable: You’ve likely heard of a Molotov cocktail, a weapon where a glass bottle filled with alcohol and a fuse, has the fuse lit and then thrown. The bottle shatters on impact, releasing (literally) flaming-hot alcohol and glass shards. This is all thanks to the fact that alcohol is flammable!

Alcohol reacts with oxygen to produce carbon dioxide and water, undergoing complete combustion.

Soluble in Water: Alcohol molecules are polar, meaning they dissolve in polar solvents like water.

Form Neutral Solutions: Alcohols are neither alkaline nor acidic, meaning the solutions they form upon dissolving in water have a neutral pH.

Form Carboxylic Acids: Upon adding an extra oxygen to an alcohol (oxidation), we get the functional group –COOH, which belongs to carboxylic acids!

Uses of Alcohols

Weapons: Two words. Molotov. Cocktail.

Fuels: Due to its flammable nature, alcohol can be combusted and used as a fuel that releases a lot of heat energy. Examples include spirit burners, which are used in place of Bunsen burners at times. While the latter runs on natural gas, the former uses alcohol as a fuel to burn.

Drinking: This is self-explanatory. Yo ho ho and a bottle of rum!

Industrial Solvents: Alcohol is often used because it dissolves things that water can’t, like lipids such as oil, as well as hydrocarbons.

Antiseptics: Don’t drink your sanitizer, kids! “Rubbing alcohol”, or alcohol at extremely high concentrations, is often used for sterilization of wounds and cuts. This is for a variety of reasons. Firstly, alcohols dissolve lipids, meaning they could disrupt the cell membrane of microorganisms. Secondly, they damage proteins in germs by breaking apart the bonds and forming hydrogen bonds with the molecules in the protein, denaturing them. They also evaporate quickly, meaning you don’t have to wipe your hands, risking exposure to more germs.

Esters

Esters are versatile organic compounds characterised by their functional group –COO, with a carbon double-bonded to one oxygen and single-bonded to the other. They are found in perfumes, natural fragrances, plastics, and even lipids and fats in the body!

They have an excellent fragrance, hence their usage in perfumes.

They are also volatile, which sounds dangerous, but really just means they evaporate quickly and easily, making them good for perfumes.

Esterification of Alcohols/Fischer Esterification:

In order to form esters, a process known as Fischer esterification is undertaken. In this process, a carboxylic acid is reacted with an alcohol in the presence of an acid catalyst, usually sulfuric acid, to produce an ester and water. The carboxylic acid gives up one hydrogen, which reacts with the alcohol to produce water. Meanwhile, the rest of the molecule attached to the alcohol, denoted by an “R”, bonds with the carboxylic acid, forming an ester.

This reaction is therefore a condensation reaction, as two molecules join together to form one molecule, and a small water molecule is released.

The reaction, however, is reversible! Reacting an ester with water, in exchange, gives you a carboxylic acid and an alcohol.

Uses:

• Perfumes
• Food flavorings

Carboxylic Acids

These are organic compounds with a functional group of –COOH, which form a homologous series (methanoic acid, ethanoic acid, propanoic acid, and butanoic acid). Furthermore, all the acids’ names end in “--anoic acid”, followed by the prefix depending on the number of carbons (1 carbon = methanoic acid).

!!IMPORTANT!! Note that the “C” in –COOH is counted among the carbons, despite being part of the functional group.

When writing their formulas, the –COOH goes at the end.

Making Carboxylic Acids:

Carboxylic acids are formed by the oxidation of alcohols. Alcohols already have the functional group –OH, and likely have a carbon atom somewhere. Thus, adding extra oxygen produces –COOH!

The carboxylic acid, if it has the same number of carbons as the alcohol it was made from, will adopt the same prefix as it. For example, butanoic acid made from butanol and oxygen has the same prefix.

Carboxylic acids have a high boiling point due to strong hydrogen bonds between molecules. As their chain length increases, though, their solubility in water decreases.

Physical Properties:

Colorless.

Foul-smelling: Ever wonder why locker rooms and gyms smell so bad? That’s because sebum, a compound naturally produced by the skin, contains carboxylic acids, which have notoriously bad odors.

Chemical Properties:

Weak Acids: Though this is in organic chemistry, carboxylic acids are still acids, a.k.a hydrogen donors! However, they are very weak acids, meaning they don’t fully ionize and give up their hydrogen ions, hence; the process is depicted as reversible.

The negative ion is named such that it ends in “--anoate”, with the prefix depending on the number of carbons in the initial acid.

Reactions with Metal Carbonates: Acids react with metal carbonates to produce water, salt, and carbon dioxide.

Reactions with Bases: Carboxylic acids react with bases to produce a salt and water.

Reaction with Metals: Carboxylic acids react with metals to produce salt and hydrogen.

Natural Polymers

If you need a little pick-me-up on polymers, check out the section in Grade 9 Biology. Some common and crucial biomolecules include lipids, proteins, and carbohydrates.

Proteins:

A protein is a polymer formed by multiple folded polypeptides, which are chains of amino acids. Amino acids themselves are made of three main groups: the amino group, the carboxyl/carboxylic acid group, and the R group.

The amino group and carboxyl groups are joined by a central carbon, and are found across all amino acids. The R group, however, changes depending on which amino acid it is.

Amino acids are joined together by amide/peptide bonds, which are formed through a condensation reaction.

Here, the amino group on one amino acid gives up one hydrogen, while the carboxyl group on the other amino acid gives up one hydrogen and one oxygen. This forms one molecule of water, while the remaining nitrogen and carbon bond together.

Carbs:

Carbohydrates are polysaccharides, meaning they are polymers formed from multiple monosaccharides, or subunits called glucose. They contain only hydrogen, oxygen, and carbon, hence the name CARBO-HYDRATES (carbo = carbon, hydrates = hydrogen and oxygen).

The oxygen atom in one unit of glucose becomes extremely electronegative and becomes attracted to the carbon atom in the other unit of glucose, that has a partially positive charge. Thus, the oxygen breaks its bonds with the –OH group attached to it, and bonds with the carbon, creating a disaccharide that can later become a polysaccharide. Meanwhile, the –OH group bonds with an H+ ion to form water!

Lipids:

Now, lipids are a diverse group and don’t necessarily have a single, consistent monomer, but a very common type of lipid, a triglyceride, consists of glycerol, an alcohol with –OH groups (triol) and fatty acids (carboxylic acids that are either saturated or unsaturated).

Saturated fatty acids consist of carboxylic acids joined entirely by single bonds, meaning every single carbon is bonded to a hydrogen, similar to alkanes! Saturated fats are solid at room temperature, such as butter and cheese. The straight-chain structure of these bad boys means they can easily pack together tightly, hence their solid state at room temp.

Unsaturated fatty acids consist of carboxylic acids that contain at least one double bond between carbons, meaning not all carbons are bonded to hydrogens. Those with just a single double bond are called monounsaturated fatty acids, while those with more than one are polyunsaturated fatty acids. These are found in nuts, avocados, and olive oil, and are liquid at room temperature. The presence of these double bonds causes “kinks” or bends in the structure of the fatty acids, and they lower LDL cholesterol and increase HDL cholesterol. These very kinks and bends prevent them from packing together as tightly as saturated fatty acids, hence, they are liquid.

In general, saturated fatty acids are more unhealthy than unsaturated fatty acids because they raise LDL cholesterol levels and are linked to heart disease, but a person’s overall intake of fat should be limited to live a healthy lifestyle.

Synthetic Polymers

Terylene is a type of polyester, which means at least one ester linkage is found between repeating monomers. On that basis, terylene is similar to lipids as they both have ester linkages, except that the former is a synthetic polymer, and the latter is a natural one.

Terylene is produced from a dicarboxylic acid (a carboxylic acid unit with two –COOH groups) and a diol (an alcohol unit with two –OH groups).

Properties:

Wrinkle- and shrink-resistant: Some natural fabrics like wool may shrink after multiple washes, but terylene doesn’t. It also doesn’t have wrinkles, meaning it can be blended with natural fabrics for the best of both worlds.

Rigid and durable: Terylene is incredibly durable and rigid, meaning it has many applications in industry and adventure sports.

Hydrophobic: Terylene repels water rather than accepts it, making it resistant to liquid stains as well as keeping the wearer dry.

High melting point: Terylene only melts at extremely high temperatures, making it a solid choice for industrial applications.

However, it’s costly to manufacture and bad for the environment as it isn’t biodegradable.

Uses:

• Raincoats (because it’s hydrophobic)
• Sails and nets (due to hydrophobic properties and durability)
• Plastic bottles and packaging (it’s a polyester, just like PET)

Nylon was developed by DuPont de Nemours, an American chemical company, in 1935, particularly by a man named Wallace Carothers. Despite being a wildly successful product today, Carothers took his own life just 16 months before its release onto the market due to chronic depression, never being able to see its popularity.

Nylon belongs to the family of polyamides, similar to proteins, as subunits are joined together by amide linkages.

Both of these polymers are formed through condensation polymerization, which is one of two ways synthetic polymers are formed. The other way synthetic polymers are formed is through addition reactions, like polyethylene (polyethene), polypropylene, and PVC (polyvinylchloride).

Because they are joined by amide linkages, nylon is similar to proteins! The only difference? Proteins are natural polymers, and nylon is synthetic.

Properties:

Strong (Nylon is one of the strongest fibres, making it incredibly durable and thus it can be used in industrial settings).

Lightweight (This, in combination with its strength, is another factor behind its use in industry).

Hydrophobic.

Resistant to alkalis (Though repeated exposure in large concentrations will eventually damage the fabric, nylon is more resistant to alkalis than acids).

However, white nylon can become yellow over time due to sunlight exposure, damaging the color. Furthermore, the fabric isn’t very breathable.

Uses:

• Clothing: Nylon is often mixed with other natural fabrics or even artificial ones like polyester
• Rope: Nylon is strong despite its light weight, making it ideal for climbing ropes
• Parachutes: Lightweight so it doesn’t weigh the person down, but strong enough to hold weight
• Tents/Tarpaulin Sheets: Waterproof and lightweight for outdoor use

Saponification, a.k.a Hydrolysis!

The term “saponification” comes from the Latin word “sapo”, which means soap. It’s an accurate moniker that essentially translates to the creation of soap, which is what happens in this process.

Saponification is the process of breaking down esters using water and an aqueous alkali into an alcohol and a salt of the metal and the carboxylic acid.

The alkali used are typically ones like potassium hydroxide or sodium hydroxide, that are soluble in water. Meanwhile, the most common esters used are triglycerides (triesters). Since ancient times, triglycerides have been found in animal fat. It’s believed the ancient Babylonians would boil animal fat with ashes. The ashes themselves contained potassium carbonate, which was an alkali. This would break down the fat into soap, which was then wetted and used to wash pots and pans.

The alcohol that is usually produced is called glycerol, while the salt becomes the soap. Glycerol is further purified to create glycerin, which is often added to make soaps translucent.

Oftentimes, alcohols such as ethanol are added to help the oil dissolve better in the water, as the two compounds often don’t mix.

Oil and Water With Ethanol vs Without:

In a sense, this reaction is the opposite of a condensation reaction, because here, a molecule is being split using water.

The rate of the reaction can be increased by increasing the temperature by placing it in a hot water bath. Take safety precautions when doing this with concentrated sodium hydroxide, as in a concentrated form, it can damage the eyes and skin, so wear gloves and goggles!

Finally, we can precipitate the soap from the glycerol by “salting it out”.

Salting Out

In this process, we decrease the solubility of the solvent the soap is in by adding a large volume of salt, and therefore, the soap becomes less soluble and rises to form a precipitate.

To put it simply, normally, when soap is soluble, the compounds in the soap have a certain charge. Water molecules form hydrogen bonds accordingly, and surround the molecules, dissolving it. However, if we add a large volume of NaCl (sodium chloride), the solvent becomes more attracted to it, dissolving the NaCl instead of the proteins. Thus, the proteins form a precipitate.

This precipitate can then be filtered out using a typical apparatus of a funnel and filter paper, where the glycerol is the filtrate and the soap is the residue.

To test whether what you’ve made is, indeed, soap, and not some kind of biological weapon, simply take a spatula-ful of soap, add it to a test tube with water, cork it, and shake it. If it forms a lather, congratulations! You have soap.

Soap and Detergent

Soap and Detergent

Soaps are the salts of fatty acids produced through saponification used for cleaning purposes or lubrication. There are two types of soap:

Hard soaps are solid at room temperature, and are formed from using sodium hydroxide as the alkali during saponification. These are bar soaps and round soaps. They dissolve slowly. This is because the lipid it is produced from contains esters with extremely long hydrocarbon chains attached to the ester functional groups, typically with 12 or more carbons, which are harder to break apart when heated, meaning they are solid at room temperature.

Soft soaps are liquid at room temperature, and are formed from using potassium hydroxide as the alkali during saponification. These are often the soaps that come in bottles. They dissolve quickly.

However, one thing you’ll notice across soap brands is that they never use esters with six or less carbons in a hydrocarbon chain, as they irritate the skin and smell bad.

How Does Soap Work?

Most compounds are usually either hydrophobic or hydrophilic, meaning they are either attracted to water or are repelled by it. There are, though, certain compounds that contain both hydrophobic AND hydrophilic, including soap and detergent. Soap, especially, is a surfactant, meaning it lowers the surface tension between compounds in two different phases, like between solids and liquids, or liquids and gases.

What is Surface Tension?

Surface tension is the tendency of liquids to shrink into the form with minimum surface area at rest. This is why water forms circular droplets, as they have the least surface area. This is caused by the uneven forces acting on water molecules. Molecules deep in the water have force acting on them from all directions, meaning there is no net force on them. However, molecules on the surface of the water don’t have any force acting on them from above, meaning they experience a stronger net down force, as well as a cohesive force between molecules next to it, causing to be “pulled in”, increasing the density of water droplets at the surface and pulling the water into a spherical shape.

But how is this relevant to the functioning of soap, you may ask?

Well, soap can’t wash dirt, oil, and other stains away just like that. It needs to form an emulsion with the substance and water, and with things like oil, it’s practically impossible. It’s even harder when the water keeps beading up, because then it won’t be able to fully absorb and wash away the stains with the soap molecules. Surfactants help by getting in the way! See, soap molecules contain a hydrophobic, nonpolar “tail” and a hydrophilic, polar “head”. This means that if a soap molecule enters water, the hydrophilic head will readily dissolve in water, but the hydrophobic tail nopes right out of there, preferring to stick out in the air.

This causes the molecule to position itself on the water’s surface for the optimal, lowest-energy state. As a result, though, the molecule wedges itself between the water molecules, reducing the cohesive energy between them and causing the water to spread out! This reduces surface tension!

How Do Surfactants Reduce Surface Tension?

The main action of soap depends on its ability to form micelles, which are spherical structures formed when surfactant molecules accumulate in one place.

Let’s say we’re trying to wash a shirt with oil stains on it. The oil will obviously be insoluble in water, and will just remain in the shirt. Time to bring out the soap! Now, the hydrophilic soap molecules obviously are attracted to the water, but the hydrophobic soap molecules are nonpolar, and so they dissolve in oil instead! This forms a spherical structure with the heads facing “out” into the water and the tails facing “in” to the oil.

Now, this happens at such a small scale that it appears the oil and water have mixed together, when in reality, a simple colloid has been formed. Now, when the water heads down the drain, it pulls the hydrophilic heads with it. These heads pull the tails with them, and the tails pull the oil molecules. And voila, your shirt is clean! And wet. You should probably hang it out to dry.

A similar thing happens within your cell membrane! That’s why it’s called a bilayer, semi-permeable membrane, because it’s a bilayer of lipids, with the heads dissolving in the water cytoplasm as well as the area outside the cell, and the tails in between being sandwiched.

Soaps v.s. Detergents

Detergents are similar to soaps and perform the same function. However, soaps are synthesized from natural ingredients like animal fat or vegetable oil, while detergents are made from synthetic chemicals and salts of stronger acids than of soaps.

Soaps also dissolve slower and easily biodegrade, making them better for the environment but slow at their job. They are also gentler, hence why they’re used by humans when bathing. Detergents, on the other hand, only have a few options that biodegrade, but dissolve much faster and are much harsher, which is why you want it to clean your clothes, but not what lies under your clothes. Don’t bathe with detergent, kids!

Soap and Hard Water

How Does Hard Water Affect Soap? - Biology Insights

If you don’t remember, go have a refresher on what hard water is. In short, hard water is water with a large concentration of dissolved mineral ions. Mainly groundwater, containing Ca2+ and Mg2+.

Now, typically, the hydrophilic head of the soap, that is negatively charged, has a positively-charged ion such as Na+ or K+ with it that enables it to dissolve in water, as the positive ions are attracted to the partially negative oxygen atoms.

However, Ca2+ and Mg2+ are more attracted to the negative head of the soap than the original Na+ or K+, which are displaced. As a result, two soap molecules bond to each ion, forming compounds insoluble in water like calcium/magnesium stearate. Thus, the stains are neither cleaned, as the soap never dissolves in water in the first place. The stearate precipitate forms a whitish-grey scum.

This has two consequences:

Things stay dirty: Like I said, the soap is too busy forming insoluble compounds to react with stains and form micelles, meaning the thing you want to wash never gets clean.

Furthermore, the only way to make the soap work with hard water is to keep adding soap till all the ions have been reacted with, so that it can finally form micelles.

Things get dirtier: This scum formed is sticky, sticking to showers, drains, walls, sinks, and even clothes! This creates a filthy-looking residue that’s very hard to get out.

However, we can combat this problem by using strong, synthetic detergent. Due to its different composition, detergents remain water soluble despite bonding to the ions in hard water, meaning things can still be cleaned as micelles are still formed, as long as they are in the water, they can still bind with dirt molecules and form micelles, compared to the insoluble soap scum that just forms a useless precipitate.

Hydrogenation of Oils

Remember those lipids we talked about earlier? Yeah, well, like I said, there’s saturated (alkanes) and unsaturated (alkenes) fats. Wanna know how to make an unsaturated one into a saturated one?

It’s simple– the process is called hydrogenation. It involves adding, you guessed it, hydrogen gas to unsaturated fats.

It’s not as easy as that, though. You have to heat the unsaturated fat to 60 degrees Celsius alongside a platinum catalyst before passing hydrogen gas through it.

Now, with polyunsaturated oils, you don’t have to hydrogenate all the bonds. The more you hydrogenate, the harder in texture it becomes and the more solid it becomes, the less you hydrogenate, the more liquid and softer it remains.

Materials (Nelson Textbook Topic #4– Materials!)

Kevlar

Kevlar: A polyamide stronger than steel, used to make bulletproof vests and brake pads in cars.

Spandex (Lycra / Elastane)

Spandex a.k.a. Lycra a.k.a. Elastane: As you can guess from the name, it’s elastic, able to stretch up to 600x its original length. This is thanks to its structure with polymer chains that are both flexible enough to stretch, but also rigid enough to maintain its shape. The material is light, comfy, and bacteria-resistant thanks to treatments done in the manufacturing process, and UV-resistant thanks to the addition of UV inhibitors in the process of making it, as well as dries quickly, hence, it’s used to make swimwear as well as crepe bandages.

However, the fibres are prone to UV degradation, and since it stretches, it creates microscopic gaps that may allow UV to enter and affect the body.

Gore-tex (it’s not what it sounds like, I swear)

This is a material where a thin sheet of plastic Teflon is stretched between two layers of fabric. The sheet itself has holes big enough to allow sweat droplets to escape, but doesn’t allow water droplets from the outside to enter, keeping out the rain.

Teflon itself is made of the monomer tetrafluoroethene (or tetrafluoroethylene, if you prefer). Gore-tex is mainly used in waterproof clothing and shoes.

Thinsulate

This material is made of fine polypropene fibres about 1/100th the thickness of human hair! Despite this, these fibres are arranged so as to trap air, a poor conductor of heat and therefore a good insulator, between them, to keep people warm. Furthermore, it’s a poor absorber of water, so you’re still warm even when you’re wet, making it flexible and a good choice for skiers.

Non-Polymers

Carbon Fibres

Carbon Fibres: These bad boys found their way into sports equipment thanks to how strong they are despite their light weight. However, they aren’t a single material but rather two different materials, including thin, graphite-like carbon fibres mixed with plastic epoxy resin. It’s used in sports bikes, golf club shafts, and tennis rackets, as well as gym equipment too.

Titanium

Titanium: Despite being very strong and having low fatigue resistance, which is to say it doesn’t weaken over time, it is lightweight and has low density. Thus, it is used in golf clubs and scuba diving equipment, because it is also corrosion resistant, which is needed in the presence of salt water. Furthermore, as it doesn’t affect the human skin by not causing allergies, it is used in artificial hearts and bone implants.

Smart Materials

These bad boys change in response to changes in their environment, such as:

Chromogenic Materials

A change in voltage or temperature causes their colour to change. Examples include liquid crystal displays and light-sensitive sunglasses.

Non-Newtonian Fluids

Depending on the force applied, these liquids become more or less viscous. A famous example is Oobleck, a mixture of corn flour and water, which turns into a solid temporarily if you apply a large amount of force, and turns into a liquid if you apply less force.

Piezoelectric materials change shape when the voltage applied is changed.

Hydrogels

When the environment changes, they change their shape, too! They also have the ability to absorb 500 times its own weight in water, hence used in absorbent materials like baby napkins, water crystals, and wound dressings. This is because the negative ions in the hydrogel attract water molecules. They contain cross-linked carboxylic acids, which is to say, linear chains of carboxylic acids bond vertically with each other instead of horizontally, meaning molecules between chains can be eliminated vertically. You can find these in hair gels, plant water crystals, wound dressings, and disposable baby napkins.

However, if salt is added to the hydrogel, it will prefer to attract sodium ions instead of water, causing it to lose water. A similar effect occurs with changes in pH.

Shape Memory Alloys

Though bendable, if you heat these alloys, they return to their original shape. This is because they have two different crystal structures, one being stable at higher temperatures (heating) and the other stable at lower temperatures (room temperature). This means at colder temperatures, these alloys are soft and easy to bend, but when heated, they’re harder. Thus, they’re used to make artificial hip joints. Examples include nitinol, a nickel-titanium alloy.

Nanoparticles!

These particles have a size range between 0.01–100 nanometers, and as a result have a high surface area to volume ratio, making them effective catalysts. Their small size makes them efficient at trapping air, too, making them good insulators, and their small shape allows for the manufacturing of better cutting tools and drill bits, making the blade and edges sharper.

They are also used in aircraft wings because their small size prevents disasters like nanocracking from happening, and makes the wings more lightweight for the same strength.

These can be used for transport of drugs within the body, such as gold nanoshells that carry anti-cancer drugs that it releases on impact in the acid environment of a tumor cell.

Molecular Gastronomy

Fancy words for those really cool dishes you see served at posh restaurants which seem to defy the laws of science but also come in really small portions that cost way too much.

A good example of the use of chemistry in cooking is emulsions, as many dressings and sauces like mayonnaise are emulsions of oil and water, held together by emulsifiers like egg yolks.

Another example is foam, used in dishes like pavlova to make them airy, fluffy, and light, which are then baked for a crumbly texture. This is made from egg whites and water, with the proteins in the egg whites trapping air to form a mesh structure that holds together, creating a stable foam.

• A pavlova next to Pavlova Cookie from CRK.