Electrolysis Flashcards
What is electrolysis?
What is an electrochemical cell?
Electricity that causes chemical reactions.
Uses REDOX reactions to convert chemical energy into electrical energy.
Uses of electrolysis
anodising aluminium-when oxygen produced at the positive electrode reacts with the aluminium to form aluminium oxide, electroplating- putting a layer of metal on the surface of another metal, refining copper, sea water can produce chlorine.
Examples of combustion
carbon + oxygen - carbon dioxide + HEAT
C + O2 - CO2 + HEAT
How to stop corrosion
coat in plastic, paint, oil, another metal less reactive than it, galvanize it-coat in layer of zinc
Activity series
arranged most reactive (top) to least reactive (bottom), used to predict what will happen in reactions with metals and metal solutions, more reactive metal displaces less reactive metal.
Thermite reactions
An exothermic reaction between aluminium powder and iron oxide and produces large amounts of heat and light. Used to weld lengths of railway track together. A displacement reaction, aluminium is more reactive than iron so it frees iron metal from it’s compound.
2Al + Fe2O3 - Fe2 + Al2O3
Uses of hydrogen
Fill weather balloons, in rockets of a space shuttle, oxy-hydrogen flames for cutting and welding steel under water, manufacture of ammonia, make soaps, candles and margarine.
Examples of respiration
glucose + oxygen - carbon dioxide + water + ENERGY
C6H12O6 + 6O2 - 6CO2 + 6H2O + ENERGY
Uses of carbon dioxide
Used by green plants in photosynthesis, breathed out during respiration (produced in body), produced by power stations that burn coal, produced by cars that burn petrol, diesel or gas, produces bubbles in drinks and makes it tangy, used in fire extinguishers, especially for electrical fires. Forms a gaseous blanket over fire and stops air getting into it, smoke used in smoke machines
Redox reactions
magnesium + oxygen - magnesium oxide
Corrosion (REDOX reaction)-
Occurs when a metal reacts with oxygen and water. The metal corrodes which is a process called rusting. The metal loses electrons to become positive ions, which is oxidation. The oxygen molecules gain the electrons to form hydroxide, which is reduction.
O2 + 2H2O + 4e- - 4OH-
The iron ions and the hydroxide ions combine to form iron oxide (rust).
iron + oxygen - iron oxide
4Fe + 3O2 - 2Fe2O3
Mitosis
- Mitosis- where a single egg grows and produces all cells to make up a baby and produce more cells to continue to grow into an adult.
- Process- One cell divides into two cells, both identical to original cell. Dividing cell is called parent cell, the two newly formed cells are called daughter cells. Nucleus information is copied exactly.
- When a cell is about to divide during mitosis, the material from the nucleus forms chromosomes which are large threads of DNA.
- Every cell with a nucleus in the body, excluding sex cells, contains 46 chromosomes (23 pairs) that are only seen when the cell is going to divide.
- In cell division, each chromosome makes a copy of itself and then the individual chromosomes and their copies line up in the cell centre. The chromosomes separate from their copies and two new cells form.
- Identical cells need to be made as mitosis is used for growth and to replace damaged and worn-out cells in the body.
- Occurs in areas where growth takes place. Nerve cells can’t replace themselves if they’re damaged.
Meiosis
- Meiosis- when an egg and sperm cell join together to form one cell with 46 chromosome, each body cell is made from this cell. The egg and sperm cells each contain 23 chromosomes each.
- Cells in ovaries and the testes, reproductive system, carry out meiosis.
- Process- The daughter cells produced have half the chromosomes as the parent cell. Chromosomes make copies of themselves before separating into two new daughter cells. The chromosomes within each daughter separate again. In meiosis four daughter cells are produced, each with half the number of chromosomes as the parent cell. Therefore they have only 23 chromosomes instead of 46 chromosomes.
DNA
- Deoxyribonucleic acid- chemical that contains all genetic information to make an individual
- Chromosomes are long threads of DNA.
- Each chromosome contains 4 bases: adenine (A), thymine (T), guanine (G), cytosine (C).
- Adenine and thymine always join up together while guanine and cytosine always pair up
- DNA molecule is like a twisted ladder of base pairs called a double helix. The bases on one length of the double helix join to the bases on the opposite strand. The ‘rungs’ of the ladder are formed by the base pairs.
- In cell division, the DNA is copied and so the double helix ‘unzips’ and therefore, since the adenine and thymine pair up and the guanine and cytosine pair up, each strand can be copied by adding the missing base to another pair, so then identical copies of the DNA molecule can be made. These two DNA strands then separate and move into each new daughter cell, so then each new cell contains the same DNA to the parent cell.
What are genes?
There are different base patterns formed along a chromosome called, genes. The sequencing of the bases along the DNA and position of genes is what gives human variation a distinct set of characteristics from everyone else. They are the code/blueprint for all the cell functions in the body, characteristics that make each organism different and are the plans to build individual organisms. They are the code to tell body cells how to make proteins and control how those proteins work in the body. The genes and proteins made by genes, determine how an organism develops from and individual cell into an adult, what nutrients are made in the body, the types of enzymes produced, and determines how a person looks and behaves.
DNA bases sequences used to form an amino acid:
- Three bases together form the code for one amino acid.
- Amino acids are the basic building blocks of proteins.
- There are 20 different types of amino acids in the body.
- Different combinations of amino acids make different proteins.
- Each amino acid has several different three-based codes to make it.
