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Chemical change

In a chemical change, bonds are broken and new bonds are formed between different atoms. This breaking and forming of bonds takes place when particles of the original materials collide with one another. Some exothermic reactions may be hot enough to cause certain chemicals to also undergo a change in state; for example in the case of aqueous solutions, bubbles may not necessarily be newly produced gas but instead water vapor.

Whenever chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated. An example of a chemical change is the reaction between sodium hydroxide and hydrogen chloride to produce sodium chloride, or table salt. This reaction is so exothermic, meaning it releases heat in the form of energy, that even flames are generated. This is an example of a chemical change because the end product is molecularly different from the starting molecules.

Chemical changes are happening all the time. There are several different types of chemical change, including: synthesis, decomposition, single displacement, double displacement, neutralization, precipitation, combustion and redox.

Examples of chemical changes

A primary example of chemical change is the combustion of methane to produce carbon dioxide and water.

Other examples of chemical changes are:

Evidence of a chemical change:

The following can indicate that a chemical change took place, although this evidence is not conclusive:

  • Change of odor
  • Change of color (for example, silver to reddish-brown when iron rusts).
  • Change in temperature or energy, such as the production (exothermic) or loss (endothermic) of heat.
  • Change of form (for example, burning paper).
  • Light, heat, or sound is given off.
  • Formation of gases, often appearing as bubbles.
  • Formation of precipitate (insoluble particles).
  • The decomposition of organic matter (for example, rotting food).

A chemical change can have a huge impact on a physical change.

Laws of chemical changes

Chemical law

Accelerating change

In futures studies and the history of technology, accelerating change is a perceived increase in the rate of technological (and sometimes social and cultural) progress throughout history, which may suggest faster and more profound change in the future. While many have suggested accelerating change, the popularity of this theory in modern times is closely associated with the ideas and writings of Raymond Kurzweil, especially in relation to his theories about technological singularity.

Early theories

In 1938, Buckminster Fuller introduced the word ephemeralization to describe the trends of "doing more with less" in chemistry, health and other areas of industrial development. In 1946, Fuller published a chart of the discoveries of the chemical elements over time to highlight the development of accelerating acceleration in human knowledge acquisition.

In 1958, Stanisław Ulam wrote in reference to a conversation with John von Neumann:

One conversation centered on the ever accelerating progress of technology and changes in the mode of human life, which gives the appearance of approaching some essential singularity in the history of the race beyond which human affairs, as we know them, could not continue.

In his book "Mindsteps to the Cosmos" (HarperCollins, August 1983), Gerald S. Hawkins elucidated his notion of 'mindsteps', dramatic and irreversible changes to paradigms or world views. He identified five distinct mindsteps in human history, and the technology that accompanied these "new world views": the invention of imagery, writing, mathematics, printing, the telescope, rocket, computer, radio, TV... "Each one takes the collective mind closer to reality, one stage further along in its understanding of the relation of humans to the cosmos." He noted: "The waiting period between the mindsteps is getting shorter. One can't help noticing the acceleration." Hawkins' empirical 'mindstep equation' quantified this, and gave dates for future mindsteps. The date of the next mindstep (5; the series begins at 0) is given as 2021, with two more successively closer mindsteps, until the limit of the series in 2053. His speculations ventured beyond the technological:

Since the late 1970s, others like Alvin Toffler (author of Future Shock),Daniel Bell and John Naisbitt have approached theories of postindustrial societies. They argue the industrial era is coming to an end, and services and information are supplanting industry and goods. Some more extreme visions of the postindustrial society, especially in fiction, envision the elimination of economic scarcity.

Many sociologists and anthropologists have created social theories dealing with social and cultural evolution. Some, like Lewis H. Morgan, Leslie White, and Gerhard Lenski, declare technological progress to be the primary factor driving the development of human civilization.

Morgan's concept of three major stages of social evolution (savagery, barbarism, and civilization) can be divided by technological milestones, like fire, the bow, and pottery in the savage era, domestication of animals, agriculture, and metalworking in the barbarian era and the alphabet and writing in the civilization era.

Instead of specific inventions, White decided that the measure by which to judge the evolution of culture was energy. For White, "the primary function of culture" is to "harness and control energy." White differentiates between five stages of human development: In the first, people use energy of their own muscles. In the second, they use energy of domesticated animals. In the third, they use the energy of plants (agricultural revolution). In the fourth, they learn to use the energy of natural resources: coal, oil, gas. In the fifth, they harness nuclear energy. Craig Brownell suggests that there could be a sixth stage in this series: the utilisation of zero-point vacuum quantum fluctuation energy, for propulsion if not actual power generation. There is much debate over whether Casimir effects can be exploited, however.

White introduced a formula P=ET, where E is a measure of energy consumed, and T is the measure of efficiency of technical factors utilizing the energy. In his own words, "culture evolves as the amount of energy harnessed per capita per year is increased, or as the efficiency of the instrumental means of putting the energy to work is increased." The Russian astronomer Nikolai Kardashev extrapolated this theory to create the From Yahoo Answers

Question:1. What is the law of conservation of Matter 2. What is the law of conservation of Mass and how does it differ to the law of conservation of Matter 3. Who founded the law and how/why did s/he do it 4. How did this discovery help scientists in today's world Please help me

Answers:1 / 2 The law of conservation of mass, also known as principle of mass/matter conservation is that the mass of a closed system (in the sense of a completely isolated system) will remain constant over time. The mass of an isolated system cannot be changed as a result of processes acting inside the system. A similar statement is that mass cannot be created/destroyed, although it may be rearranged in space, and changed into different types of particles. This implies that for any chemical process in a closed system, the mass of the reactants must equal the mass of the products. 3. Beginnings of the theory of conservation of mass were stated by Epicurus (341 270 BC). Describing the nature of the universe, he wrote: "the sum total of things was always such as it is now, and such it will ever remain," and that nothing is created from nothing, and of the conservation of mass was stated by Nas r al-D n al-T s (1201 1274) during the 13th century. He wrote that a body of matter is able to change, but is not able to disappear. The principle of conservation of mass was first outlined clearly by Antoine Lavoisier (1743 1794) in 1789, who is often for this reason referred to as an initiator of modern chemistry. However, Mikhail Lomonosov (1711 1765) had previously expressed similar ideas during 1748 and proved them by experiments. Others who anticipated the work of Lavoisier include Joseph Black (1728 1799), Henry Cavendish (1731 1810), and Jean Rey (1583 1645). 4. Once understood, the conservation of mass was of great importance in changing alchemy to modern chemistry. When chemists realized that substances never disappeared from measurement with the scales (once buoyancy effects were held constant, or had otherwise been accounted for), they could for the first time embark on quantitative studies of the transformations of substances. This in turn produced ideas of chemical elements, as well as the idea that all chemical processes and transformations (including both fire and metabolism) are simple reactions between invariant amounts or weights of these elements.

Question:For example, if you melted an ice cube into water, would the water weigh the same as the ice cube did?

Answers:No to the bold subject, yes to the small question. (But, your terminology is wrong.) The law of conservation of mass states that matter can neither be created nor destroyed. **In other words, if an ice cube melts the water created has the same mass as the ice did.** Your terminology is wrong because the water doesn't necessarily have to "weigh" the same thing. If a chemical reaction occurs, weight may change slightly. But, 'mass' is always a constant in a closed system (such as the one you are describing).

Question:I. Please state whether the following are PHYSICAL or CHEMICAL properties. If physical, identify whether extensive or intensive. 1. melting point of platinum- 2. corrosiveness of an acid- 3. color of leaves- 4. the volume of beer in a mug- 5. electrical conductivity- 6. boiling point temperature of water- 7. explosion of nitrogen triiodide- 8. the pressure of air in tire- 9. electrolysis of water- 10. density of alcohol- II. Please identify the type of change (physical or chemical) that is involved in the following processes. 1. plant carrying out phototosynthesis- 2. dissolving sugar crystals in water- 3. cutting aluminum foil- 4. burning natural gas to a blue flame- 5. blowing up a balloon- 6. caramelizing sugar- 7. formation of clouds- 8. butter melting in a pan- 9. ripening of fruits- 10. popping popcorn- 11. igniting a firecracker- 12. liquid water turning to steam- 13. rusting of iron- 14. combustion of fuel- 15. cooling mercury to a silvery solid- Thank you. ^^

Answers:If you really want help put your answer in and people can correct or advise you. Remember those of us who can answer your question have learnt what is involved, not just let somebody else do the work.

Question:name the physical properties you would use to tell the difference between the following pairs of objects 1. coal and snow 2. vinegar and water 3. lead and copper 4. strawberry and vanilla ice cream 5. salt and sugar 6. a baseball and a football 7. cubes of silver and platinum 1. what physical property could you use to seperate sand and sugar? how would you use it? 2. use the law of conservation of mass to explain why a rusty nail weighs more than the original nail 1. the melting point of ice is a __________property 2. density is a ___________ property. 3 ___________ changes produce new substances 4. the total_____________of original and new substances is the same after a chemical change 5. stainless steel's ability to resist rust is a _________ property 6. the unit of measuring density is __________ 7. the ______________point of water is 100 degrees celcuis 8. natural gas for cooking has the property of ____________ 9. the particles of a gas have ____________between them 10. ductility is a ____________ property of copper some of these words can be used more than once chemical physical rusting luster reacting heated evaporating matter 1. ______________ has undergoes 2.__________ 3.____________ 4.___________ 5.________ properties such as properties such as changes such as changes {# 5 continued}such as burning and 6.___________ 7.____________ 8.________ 9.__________ and volume (#7)with oxygen and changing when (#9) & melting 10.______________

Answers:1. color 2.odor 3.color or density 4.color 5.heat would melt the sugar, you should not taste them, also salt crystals are cubes 6.shape 7.density 1. P 2. P 3. C 4. mass 5.C 6. g/ml 7. bp 8.burning-chemical property 9. more space 10. P

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