CARBOHYDRATES: C n (H 2 O) m

1. 1. Szénhidrátok - Carbohydrates A szacharidok – Saccharides A szőlőcukor – Glukose Ezüsttükör próba – (Tollens reaction)2. Redoxi reakciók (Redoxi reactions) Al + I2 , Daniell elem

2. CARBOHYDRATES:Cn(H2O)m Structurally it is more accurate to view them as polyhydroxy aldehydes and ketones. synonym of saccharide. The carbohydrates (saccharides) are divided into four chemical groupings: monosaccharides, disaccharides, oligosaccharides (oligo = few, 3-10), and polysaccharides. In general, the monosaccharides and disaccharides, which are smaller (lower molecular weight) carbohydrates, are commonly referred to as sugars.The word saccharide comes from the Greek word σάκχαρον (sákkharon), meaning "sugar". The names of the monosaccharides and disaccharides very often end in the suffix -ose. For example, blood sugar is the monosaccharide glucose, table sugar is the disaccharide sucrose, and milk sugar is the disaccharide lactose (see illustration).

3. Role in living organisms? Carbohydrates perform numerous roles in living organisms. Polysaccharides serve for the storage of energy (e.g., starch and glycogen), and as  structural components (e.g., cellulose in plants and chitin in arthropods). The 5-carbon monosaccharide ribose is an important component of coenzymes (e.g., ATP, FAD, and NAD) and the backbone of the genetic molecule known as RNA. The related deoxyribose is a component of DNA.  Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, fertilization, preventing pathogenesis, blood clotting, and development.

4. Csoportosításuk: Monosaccharides are classified according to three different characteristics: - where is the carbonyl {=O} group, - how many carbon atoms it contains, - chiral handedness. If the carbonyl group is an aldehyde, the monosaccharide is an aldose; if the carbonyl group is a ketone, the monosaccharide is a ketose. Monosaccharides with three carbon atoms are called trioses, those with four are called tetroses, five are called pentoses, six are hexoses, and so on. These two systems of classification are often combined. For example, glucose C6H12O6 is an aldohexose (a six-carbon aldehyde), ribose is an aldopentose (a five-carbon aldehyde), and fructose is a ketohexose (a six-carbon ketone).

5. Szőlőcukor (glucose, other names: blood sugar, dextrose, corn sugar, grape sugar) gyűrűvé záródik az 1. és az 5. szénatomoknál, így ni:

6. Ezüsttükör próba (Tollens test) to see if it can reduce Ag+ to Ag ANYAGOK: 10 w% szőlőcukor-oldat (glucose sol.) 1 w% ezüst-nitrát-oldat, (AgNO3 (sol.) 2 mol/dm3 ammóniaoldat, (NH4OH sol.) ESZKÖZÖK: kémcső (very clean test tube), vízfürdő/hot bath 80ºC VIZSGÁLAT: kémcsőbe öntsünk 4 cm3 1 tömegszázalékos ezüst-nitrát-oldatot, majd adjunk hozzá annyi ammóniaoldatot, hogy a képződő csapadék éppen feloldódjék. Ezután öntsünk a kémcsőbe 2 cm310 tömegszázalékos szőlőcukor-oldatot, rázzuk össze, majd tegyük a kémcsövet 80 Celsius-fokos vízfürdőbe. KÉRDÉSEK: Milyen változást tapasztalt a kémcsövekben? Mivel magyarázható a jelenség? Milyen szerves anyagokkal végezhető el a kísérlet?

7. KÉRDÉSEK: Milyen változást tapasztalt a kémcsövekben? Mivel magyarázható a jelenség? Milyen szerves anyagokkal végezhető el a kísérlet? TAPASZTALAT: A színtelen oldat megbarnul, majd megfeketedik, 3-4 perc alatt a kémcső falán fényes, összefüggő ezüstréteg válik ki.MAGYARÁZAT: A szőlőcukor oxocsoportja az ezüstiont fémezüstté redukálja. Aldehidekkel, redukáló szénhidrátokkal.

8. Other redoxi reactions (Revision) Al + I2→ AlI3 exothermic cathalist: Al → Al 3+ + 3 e- I2 + 2e- → 2I-

9. Daniell elem/cell

10. History The Daniell cell was invented in 1836 by John Frederic Daniell, a British chemist and meteorologist. It consisted of a copper pot filled with a copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid and a zinc electrode. He was searching for a way to eliminate the hydrogen bubble problem found in the Voltaic pile, and his solution was to use a second electrolyte to consume the hydrogen produced by the first. Zinc sulfate may be substituted for the sulfuric acid.

11. The powerful potato chemical energy is converted to electric energy by a spontaneous electron transfer. In the case of the potato, the zinc reacts with the copper. The potato acts as a sort of buffer between the zinc ions and the copper ions. The zinc and copper ions would still react if they touched within the potato but they would only generate heat. Since the potato keeps them apart, the electron transfer has to take place over the copper wires of the circuit, which channels the energy into the clock.

12. What happens? • In a lemon battery, both oxidation and reduction occur. • At the anode, metallic zinc is oxidized, and enters the acidic solution as Zn2+ ions: Zn → Zn2+ + 2 e-. • At the copper cathode, hydrogen ions (solvated protons from the acidic solution) are reduced to form molecular hydrogen: 2H++ 2e- → H2.