Carbohydrate-sources and nomenclature, Properties, carbohydrate as polymer, uses.

SECOND TERM E-LEARNING NOTES

SUBJECT: CHEMISTRY

CLASS: SS3

WEEK 1

TOPIC: GIANT MOLECULES

CONTENT:

1. SUGARS (CARBOHYDRATE)
2. HYDROLYSIS OF SUCROSE AND STARCH
3. PROTEINS

PERIOD 1: SUGARS

Carbohydrates are natural compounds of carbon, hydrogen and oxygen wherein the ratio of atoms of hydrogen and oxygen is 2:1.

The final molecular method of carbohydrate is C_x(H₂O)_y or C_xH_2yO_y

CLASSIFICATION

The classification is predicated on the impact of acid hydrolysis of carbohydrates.

MONOSACCHARIDES: These are easy sugars. Examples are glucose and fructose. They can’t be cut up into easy molecules by acid hydrolysis.

Construction of glucose and sucrose

DISACCHARIDES: They’re additionally sugars e.g. sucrose, maltose, and lactose. They are often cut up into two molecules of monosaccharide by acid hydrolysis.

POLYSACCAHRIDES: They’re also referred to as advanced sugars. They’re no-crystalline, insoluble and tasteless substance e.g. starch and cellulose. They are often hydrolysed to present many molecules of the identical or various kinds of monosaccharide. Different examples are glycogen (animal starch), inulin, dextrin.

SOURCES

Glucose could be present in grapes, honey, sap of crops and within the blood of animals.

Fructose is discovered along with glucose in candy fruit juices and honey.

Sucrose or cane sugar is the widespread granulated sugar which we use to sweeten meals.

It’s happens naturally in lots of crops and fruits e.g. pineapple, carrots, sorghum and the sap of the sugar maple tree. The principle sources are sugar cane and sugar beet.

Starch happens naturally in most crops as a saved carbohydrates e.g. maize (corn), cassava, yam, cocoyam, potatoes, rice, wheat, barley and different cereals.

Starch consists of thousand of repeating glucose items linked collectively to type a large branched molecule.[mediator_tech]

Cellulose: it’s composed of glucose items that are linked in a barely totally different approach from that in starch. It’s present in cotton wool, hemp, jute, flax, sisal and straw

EVALUATION

1. (a) What’s the basic molecular method for carbohydrate?
2. Identify three sorts of carbohydrate with two examples every?

PERIOD 2: REDUCING AND NON-REDUCING SUGARS

Sugar could be divided into lowering sugars and non-reducing sugars. Decreasing sugars will also be subdivided into monosaccharide e.g. glucose, fructose, galactose, mannose, and so forth. and disaccharides e.g. maltose, lactose and so forth. non-reducing sugars are disaccharides of sucrose.

HYDROLYSIS OF SUCROSE AND STARCH

Sucrose could be hydrolyzed by dilute acids to yield monosaccharide

Starch could be hydrolysed with mineral scorching mineral acid to glucose.

The enzyme, diastase current in malt may even hydrolyze starch to maltose and with the addition of yeast; the maltase in yeast will convert maltose to glucose.

Enzyme hydrolysis:

Diastate nH₂O/Maltase

2(C₆H₁₀O₅)_{n (aq)} + nH₂O nC₁₂H₂₂O_11(aq)

nC₆H₁₂O_6(aq)

EVALUATION

1. State one predominant distinction between a monosaccharide and a disaccharide.

2. Identify the:

(a) Class of carbohydrate to which starch and cellulose belong?

(b) The product of advanced enzyme – catalyzed hydrolysis of starch.

1. Write an equation to characterize hydrolysis of starch.

PERIOD 3: TEST FOR STARCH AND SUGARS

STARCH: when an answer or suspension of starch is handled with an answer of iodine in potassium iodide, a blue black colouration is obtained.

GLUCOSE:

(a) Decreasing motion: when an aqueous answer of glucose is boiled with Fehling answer a brick purple precipitate of copper (i) oxide, Cu₂O is obtained.

(b) When an aqueous answer of glucose is warmed with an ammoniacal answer of a silver trioxonitrate (v), silver steel is deposited (silver minor or Tollen’s take a look at).

Notice:

1. Any of those two checks can be utilized to determine a lowering sugar reminiscent of glucose and to verify the presence of alkanal useful group –CHO (carbonyl group).[mediator_tech]
2. Answer of sucrose doesn’t give constructive end result with the above take a look at as a result of it isn’t a lowering sugar.

EVALAUTION:

Describe the laboratory take a look at for (i). Starch (ii). Glucose

PERIOD 4: USES OF STARCH AND GLUCOSE

STARCH:

1. As meals stuff: starch containing substances reminiscent of cassava, yam, maize, potatoes and rice when processed are the primary sources of power in our weight-reduction plan.

In actual fact, all cereal meals reminiscent of bread, biscuit and truffles are starch.

1. As a supply of dextrin – used within the manufacturing of soluble starch and gum.
2. Within the laundry and in stiffening textiles
3. In producing glucose and alcoholic drinks
4. As a uncooked materials within the industrial processes involving fermentation.

GLUCOSE:

1. Glucose is used within the manufacturing of candy jam and meals drinks reminiscent of Lucozade to interchange misplaced power.
2. As the one meals for the sick or invalids- since it’s readily absorbed into the blood.
3. As an industrial supply of ethanol.

EVALUATION: state three makes use of of (i) Glucose (ii) Glucose