Learning with Mixture

SEPARATING LIQUID/LIQUID MIXTURES
Oil and water do not mix easily. They are said to be immiscible
1.LIQUIDS WHICH ARE MISCIBLE
If miscible liquids are to be separated, then this can be done by fractional distillation. Fractional distillation relies upon the liquids having different boiling points. When an ethanol and water mixture is heated,the vapours of ethanol and water boil off at different temperatures and can be condensed and collected separately. Ethanol boils at 78 °C whereas water boils at 100 °C. When the mixture is heated the vapour produced is mainly ethanol with some steam. Because water has the higher boiling point of the two, it condenses out from the mixture with ethanol. This is what takes place in the fractionating column. :The water condenses and drips back into the flask while the ethanol vapour moves up the column and into the condenser, where it condenses into liquid ethanol and is collected in the receiving flask as the distillate. When all the ethanol has distilled over, the temperature reading on the thermometer rises steadily to 100 °C, showing that the steam is now entering the condenser. At this point the receiver can be changed and the condensing water can now be collected.
2.LIQUIDS WHICH ARE IMMISCIBLE
If two liquids are immiscible they can be separated using a separating funnel. The mixture is poured into the funnel and the layers allowed to separate...The lower layer can then be run off by opening the tap.

4.Evaporation🔆🔅♨️♨️
If the solid has dissolved in the liquid it cannot be separated by filtering or centrifuging. Instead, the solution can be heated so that the liquid evaporates completely and leaves the solid behind. The simplest way to obtain salt from its solution is by slow evaporation.
5.Crystallisation🌧️🌨️🧂🧂
In many parts of the world salt is obtained from sea water on a vast scale. This is done by using the heat of the sun to evaporate the water to leave a saturated solution of salt known as brine. A saturated solution is defined as one that contains as much solute as can be dissolved at a particular temperature. When the solution is saturated the salt begins to crystallise, and it is removed using large scoops.

Centrifuging 🧪💉
Another way to separate a solid from a liquid is to use a centrifuge. This technique is sometimes used instead of filtration. It is usually used when the solid particles are so small that they spread out (disperse) throughout the liquid and remain in suspension.They do not settle to the bottom of the container, as heavier particles would do, under the force of gravity. The technique of centrifuging or centrifugation involves the suspension being spun round very fast in a centrifuge so that the solid gets flung to the bottom of the tube..The pure liquid can be decanted after the solid has been forced to the bottom of the tube. This method of separation is used extensively to separate blood cells from blood plasma. In this case, the solid particles (the blood cells) are flung to the bottom of the tube, allowing the liquid plasma to be decanted.

🧪🥃🧂SEPARATING TECHNIQUES 🧪🥃🧂

SEPARATING SOLID/LIQUID MIXTURES.
If a solid substance is added to a liquid it may dissolve to form a solution. In this case the solid is said to be soluble and is called the solute. The liquid it has dissolved in is called the solvent. An example of this type of process is when sugar is added to tea or coffee or water. Sometimes the solid does not dissolve in the liquid. This solid is said to be insoluble.
1.Filtration🥃🕸️
When a cup of tea is poured through a tea strainer you are carrying out a filtering process. Filtration is a common separation technique used in chemistry laboratories throughout the world. It is used when a solid needs to be separated from a liquid. For example, sand can be separated from a mixture with water by filtering through filter paper.It is important when filtering not to overfill the filter paper. The filter paper contains holes that, although too small to be seen, are large enough to allow the molecules of water through but not the sand particles. It acts like a sieve. The sand gets trapped in the filter paper and the water passes through it. The sand is called the residue and the water is called the filtrate.
2.Decanting🧪🧪🧪
Vegetables do not dissolve in water. When you have boiled some vegetables it is easy to separate them from the water by pouring it off. This process is called decanting. This technique is used quite often to separate an insoluble solid, which has settled at the bottom of a flask, from a liquid.

The large intestine
The large intestine has two parts:a the ascending, transverse and descending colona the recturn, where faeces can be stored for about 24 hours before being egested through the a**s during defecation. The colon is wider than the ileum and its ridged lining contains manvmucus secreting cells. There is no digestion in the colon. It has two main functions:
* absorption of mineral salts and water
*preparing faeces for egestion
The remaining undigested food passing from the small into the large intestine contains a lot of water. This is not the water you drink, which is mainly absorbed in the stomach. It is water from all the secretions such as bile and pancreatic juice, that have been added to the food along the alimentary canal. This may be as much as ten litres of water per day. As the contents of the ileum pass through the colon, most of the water is reab-sorbed into the body, so the contents of the colon become firmer. Finally, the undigested food remains, called faeces, enters the re**um where it remains until egested.
Assimilation
Once absorbed into the bloodstream, the molecules produced by digestion are taken by the hepatic portal vein to the liver. The liver processes them invarious ways before they pass to the rest of the body.

3. The epithelium (lining) of the villi is very thin so that soluble sub-stances can easily pass through. The membrane of each epithelial cell Iining the outside of the villus is also folded to form microvilli. 4.There are many mitochondria in the epithelial cells lining the small intestine to provide energy for the uptake of digested food by active transport.
5. The ileum has an extensive blood supply and lymph capillaries, called lacteals, to pick up molecules produced by digestion and transport them away from the gut.The blood rapidly removes molecules absorbed by the cells lining the villi.This helps to maintain a steep diffusion gradient from the lumen of the gut to the blood stream down which molecules can diffuse. Some sub-stances, such as sodium ions, are absorbed by active transport. Fatty acids and glycerol are absorbed into the lacteals, part of the lymph system. Water and vitamins are also absorbed in the small intestine.Glucose and amino acids are carried in the blood through the hepatic portal vein to the liver. Here they may be stored temporarily or processed by the liver before being transported to other body tissues. Some fatty acids and glycerol may also be transported in the blood but most of the molecules pass into the lacteals. They are then transported through the lymph system and into the blood stream. At the end of the small intestine are the caecum and appendix. These are very small in humans and play no specific role in digestion. However, the caecum plays an important role in the digestion of cellulose in herbivorous mammals such as rabbits.🐰🐇🐇🐇

Villi
Cells lining glands called the crypts of Lieberkuhn in the walls of the duodenum also secrete a number of enzymes collectively called the succusentericus:
A. lipase catalyses the hydrolysis of lipids to fatty acids and glycerol
B. maltase catalyses the hydrolysis of maltose to glucose
C. lactase catalyses the hydrolysis of lactose to glucose and galactose
D. sucrase catalyses the hydrolysis of sucrose to glucose and fructose
E.enterokinase converts trypsinogen to trypsina peptidase catalyses the hydrolysis of peptides to amino acids.
The enzymes released into the small intestine do not digest the intestine wall, which is made of proteins and lipids, because the wall has special-mucus secreting cells. The mucus protects the lining of the small intestine.
Also, the enzymes are only secreted when food is present.Absorption in the small intestine
Absorption is the process by which the small soluble molecules produce by the digestion of food enter the blood and lymph from the lumen of the gut. Absorption takes place mainly in the ileum, which is adapted to the function in several ways:
l. It is the longest part of the gut, ensuring that most of the soluble food are absorbed.
2. It has an inner surface folded into thousands of microscopic flnger-like projections called villi. These produce an enormous surface area for the absorption of the products of digestion. The villi are in constant motion. Each slowly contracts and expands

Biology 🍰🍞🍞🥯🤰👀👻🗣️
The small intestine
The small intestine, at 7 m long in humans, is the longest part of the ali-mentary canal. It is divided into two sections: the duodenum, the first 25cm, and the ileum.In the small intestine, the digestion of proteins, starch and lipids is completed. The duodenum secretes a hormone secretin, which in turn triggers the gall bladder to eject stored bile, made by the liver, and the pancreas to secrete pancreatic juice. These enter the duodenum through a duct. Bile is an alkaline green watery fluid which contains: *inorganic salts, mainly sodium hydrogencarbonate, which neutralise the acidic chyme coming from the stomach
*organic salts, which emulsify lipids, breaking them into small droplets;this emulsiflcation increases the surface area on which lipid-digesting enzymes can work
*no enzymes
Pancreatic juice is also an alkaline fluid with a pH of 7-8. It contains:
1.sodium hydrogencarbonate to neutralise the acidic chymea
2. Pancreatic amylase, which catalyses the hydrolysis of starch to maltose
3. Trypsin, a protease, secreted as an inactive molecule, trypsinogen.which catalyses the hydrolysis of proteins to peptides
4. Lipase, which catalyses the hydrolysis of lipids to fatty acids and glyc-erol.

The stomach🤰🤰🤰🤰
The stomach is a muscular bag where food eaten during a meal can be stored for processing later by the rest of the gut. When food enters the stomach:starch digestion stops because salivary amylase is denatured by the acid pH in the stomach, and protein digestion begins. Cells lining gastric glands that forms deep pits in the stomach wall secretes several substances:
l. Pepsin, a protease, secreted in an inactive form pepsinogen, catalyse.the hydrolysis of proteins to peptides.
2. Rennin, found in young mammals, converts the soluble protein:,caseinogen, found in milk, into solid casein. Pepsin then digests the casein to produce peptides.
3. Hydrochloric acid reduces the pH in the stomach to a very acid 1.5 - 2.0. This provides the optimum pH for pepsin and rennin, and kills most of the bacteria ingested with food. HCI also creates active pepsin from pepsinogen.
4. Mucus protects the walls of the stomach from the acid and protein-digesting enzymes. If insufficient mucus or too much acid are produced an ulcer can be formed in the wall of the stomach. The mucus also supplies water to mix with the food, dissolving the products of digestion prior to absorption.While in the stomach, the food is churned and mixed by peristalsis, producing chyme, a thick green liquid. The cardiac sphincter at the top of the stomach ensures that no acidic chyme enters the oesophagus. At intervals, small quantities of chyme are squirted through the pyloric sphincter muscle at the bottom of the stomach into the duodenum, the flrst part of the small intestine. Absorption of some substances, for example water and alcohol,also occur in the stomach.

The human gut🤰🤰🤰
The human gut consists of a number of discrete parts, each adapted to perform a particular function.
The mouth cavity🗣️🗣️🗣️👅👅👄👄
The mouth or buccal cavity contains the teeth, tongue and salivary glands. Food is chewed in the mouth (masticated) breaking the large food particles into smaller pieces (mechanical digestion). Food is also mixed with saliva produced by three pairs of salivary glands. Saliva:
* moistens food, dissolving soluble food molecules such as glucose
* contains mucin, important in lubricating the food so it can be swallowed easily
* contains an enzyme called salivary amylase or ptyalin, which starts the digestion of starch to maltose
* contains salts, such as sodium hydrogencarbonate, which act as a buffer,providing a very slightly alkaline pH in the mouth
Swallowing😋😋😋🦷
After chewing, a sausage-shaped bolus of food is formed by the tongue.This is then swallowed and enters the oesophagus, a muscular tube which runs from the mouth to the stomach. Swallowing is a reflex action - it occurs without being under voluntary control. As the food is swallowed, a flap of tissue called the epiglottis seals the trachea, preventing food from entering, the lungs.
The oesophagus 👻👻👻
It contains two layers of stnooth muscles, a circular and a longitudinal layer. Contraction of the circular muscle layer behind the Ioad forces it down the oesophagus. The same sorts of contractions, called peristalsis, produced by these two layers of muscle are responsible for moving food through the whole of the alimentary canal.Starch digestion continues in the oesophagus until the food enters the stomach.

Processing solid food🍹🍪🍩🥧🍰🎂🥘🌮🍕🍟🥩🍗🍞🥐🥖🥖🥯
The food taken in by holozoic heterotrophs such as humans must be broken down physically and chemically to small soluble molecules that can be absorbed from the gut into the blood. These molecules are transpoted by the blood to the liver and then to cells around the body.
The gut
The mouth is the entrance to a long tube that runs through the human body called the alimentary canal, digestive tract or gut. Food passes along this tube and is processed in various ways.
Ingestion, getting food into the mouth, takes place in a variety of ways in different animals. As the food passes along the gut it is broken down into smaller soluble molecules. This involves two processes;
*Mechanical digestion occurs when solid food is broken into smaller pieces by the chewing action of teeth and the churning of food in the stomach. By breaking up large particles of food, mechanical digestion provides a larger surface area of food for the digestive enzymes to work on and aids swallowing.
*chemical digestion is the breakdown of the large morecules in ingested food, such as proteins and starch, into smaller molecules, such as amino acids and glucose, by digestive enzymes. The small soluble molecules are then absorbed into the Blood and Lymph system. The molecules produced by this digestion can be transported to cells. Finally, food that has not been digested, mainly cellulose in human, mixed with dead cells and bacteria is egested as Feaces.

Biology 🐉🦕🦖🦖🌏🌏🌍
v)Ribosomes: These are small round structures in the cell where protein synthesis takes place.
Some ribosomes float freely in the cytoplasm while others are attached to the rough endoplasmic reticulum.
(vii)Endoplasmic Reticulum:This is a network of membranes used for transportation of substances within the cytoplasm. There are two types of endoplasmic reticulum, namely smooth endoplasmic reticulum and rough endoplasmic reticulum. Rough endoplasmic reticulum has ribosomes on its surface and transports proteins. Smooth endoplasmic reticulum has no ribosomes on its surface and transports lipids.
(viii)Golgi Bodies: These are a pile of flattened vesicles which modify and carry proteins such as enzymes from the sites of synthesis to the sites of reaction. They are collectively called the Golgi apparatus.
(ix)Chloroplasts: These are oval-shaped structures found in plant cells. They carry out photosynthesis. They contain a green pigment called chlorophyll which absorbs light energy for photosynthesis.
(x)Vacuole: This is a fluid filled space inside the cytoplasm of a plant cell. It contains a fluid called cell sap (a solution of sugars and salts in water) and is surrounded by a membrane called tanoplast. The concentration of the cell sap plays a role in the movement of water into and out of the cell.
(xi)Cell wall: This is the outermost boundary of the plant cell. It is made of a substance called cellulose. It is important for protection against damage and prevention of bursting when the plant cell gains a lot of water. It also gives shape to the plant cell. It is fully permeable to all substances.