pure substance X is solid at room temperature. If the substance is heated to 230 derajat celcius is melted gradually. if then cooled to room temperature , the liquid can not be frozen.
is it possible X of an element or a compound . Explain it
Does it a chemical change occured ? If so can it be said to undergo an endhotherm changing, based on the information provided.
can it be said that the liquid is an element , based on the information provided
Aswer:
Single chemical compound is a substance formed from multiple elements through chemical reactions and compounds also can be decomposed again into its constituent elements by chemical reactions. For example, dihydrogen monoxide (water, H2O) is a compound consisting of two hydrogen atoms for every oxygen atom.
Generally, this fixed ratio must be fixed because of the nature of physics, not the ratio of the chosen people. Therefore, materials such as brass, YBCO superconductors, semiconductors "aluminum gallium arsenide", or chocolate is considered as a mixture or alloy, not a compound.
The characteristics that distinguish compounds is that he has the chemical formula. The chemical formula gives the ratio of atoms in solids, and the number of atoms in a single molecule (hence the chemical formula C2H4 and ethene is not a CH2. The formula does not mention whether the compound is made up of molecules; for example, sodium chloride (table salt, NaCl is an ionic compound .
Compounds can exist in several phases. Most compounds can be solids. Molecular compounds can also be a liquid or gas. All compounds will break down into smaller compounds or individual atoms if heated to a certain temperature (called the decomposition temperature).
Any chemical compound that has been described in the literature have a unique identification number, ie CAS number.
Rabu, 30 November 2011
Minggu, 23 Oktober 2011
Endothermic reaction or Endotermal
Endothermic reaction is a reaction that requires energy or absorb energy from the environment when the reaction occurs, this reaction generally produces dingin.atau temperature endothermic reaction is a chemical reaction that absorbs heat. Heat is taken from the environment so that the enthalpy increases. In endothermic reactions absorb energy systems. Therefore, the enthalpy of the system will increase, meaning that the enthalpy of the product (HP) is greater than the enthalpy of reactants (HR). As a result, changes in enthalpy (ΔH), namely the difference between the enthalpy of the product with the enthalpy of reactants is positive. So that:
ΔH = HP - HR Activation Energy ΔH> 0
From the graph above, can be seen that ΔH = HP - HR. Because HR is smaller than the HP. So ΔH> 0 Examples of endothermic reaction is a reaction to the melting of ice in a container. Examples of chemical reactions from ice melt events are: Sign (+) at 6.02 kJ on the left arrow indicates that the heat is absorbed by 6.02 kJ.
REACTION ice melts Thus, the reaction can also be written as follows: In reaction to the endoderm, heat (q) absorbed so that the positive enthalpy change (ΔH> 0). The reaction can be illustrated on the chart as well.
EXAMPLES OF REACTION endothermic Other examples of endothermic reactions in everyday life include: - Dissolution of sugar. If the sugar is dissolved, it can be felt there was little sense of cold when the glass is held
The hand was cold when in contact with alcohol - Assimilation
- Photosynthesis - Burning kerosene oil stove
- Flame campfire when camping
The difference between exothermic and endothermic reactions A. Exothermic reaction Exothermic reaction occurs heat transfer from the system into the environment or on the reaction heat is released.
In the exothermic reaction of prices DH = (-)
Example: C (s) + O2 (g) → CO2 (g) + 393.5 kJ; DH = -393.5 kJ B. endothermic reaction Endothermic reaction occurs heat transfer from the environment to the system or to the reaction heat is needed.
In endothermic reactions DH Price = (+)
Example: CaCO3 (s) → CaO (s) + CO2 (g) - 178.5 kJ; DH = +178.5 kJ
Simple understanding of the endothermic reaction 1. Reactions that require heat 2. The temperature of the system C
A + B ----> C - 25 kJ C absorbed heat 25 kJ
r = p - 25 kJ
r <h = "HP"> il ΔH = +
2.1.Reaksi endothermic or Endotermal
Endothermic reaction is a reaction that requires energy or absorb energy from the environment when the reaction occurs, this reaction generally produces dingin.atau temperature endothermic reaction is a chemical reaction that absorbs heat. Heat is taken from the environment so that the enthalpy increases. In endothermic reactions absorb energy systems. Therefore, the enthalpy of the system will increase, meaning that the enthalpy of the product (HP) is greater than the enthalpy of reactants (HR). As a result, changes in enthalpy (ΔH), namely the difference between the enthalpy of the product with the enthalpy of reactants is positive. So that:
ΔH = HP - HR Activation Energy ΔH> 0
From the graph above, can be seen that ΔH = HP - HR. Because HR is smaller than the HP. So ΔH> 0 Examples of endothermic reaction is a reaction to the melting of ice in a container. Examples of chemical reactions from ice melt events are: Sign (+) at 6.02 kJ on the left arrow indicates that the heat is absorbed by 6.02 kJ.
REACTION ice melts Thus, the reaction can also be written as follows: In reaction to the endoderm, heat (q) absorbed so that the positive enthalpy change (ΔH> 0). The reaction can be illustrated on the chart as well.
EXAMPLES OF REACTION endothermic Other examples of endothermic reactions in everyday life include: - Dissolution of sugar. If the sugar is dissolved, it can be felt there was little sense of cold when the glass is held
The hand was cold when in contact with alcohol - Assimilation
- Photosynthesis - Burning kerosene oil stove
- Flame campfire when camping
The difference between exothermic and endothermic reactions A. Exothermic reaction Exothermic reaction occurs heat transfer from the system into the environment or on the reaction heat is released.
In the exothermic reaction of prices DH = (-)
Example: C (s) + O2 (g) → CO2 (g) + 393.5 kJ; DH = -393.5 kJ B. endothermic reaction Endothermic reaction occurs heat transfer from the environment to the system or to the reaction heat is needed.
In endothermic reactions DH Price = (+)
Example: CaCO3 (s) → CaO (s) + CO2 (g) - 178.5 kJ; DH = +178.5 kJ
Simple understanding of the endothermic reaction 1. Reactions that require heat 2. The temperature of the system C
A + B ----> C - 25 kJ C absorbed heat 25 kJ
r = p - 25 kJ
r <h = "HP"> il ΔH = +
endothermic reaction is a reaction that requires or absorbs heat, for example in their daily lives the most convenient way is to melt the ice event, or the manufacture of salt by heating from the sun, the wax is melted.
exothermic reaction is a reaction that occurs when a substance or object release / release of heat, in their daily lives are most easily seen is the condensation events, or the outside of the glasses full of cold water to wet the glass seolah2 leaking, but the air around the glass is a condensed ...
Endothermic reaction is a reaction that requires energy or absorb energy from the environment when the reaction occurs, this reaction generally produces dingin.atau temperature endothermic reaction is a chemical reaction that absorbs heat. Heat is taken from the environment so that the enthalpy increases. In endothermic reactions absorb energy systems. Therefore, the enthalpy of the system will increase, meaning that the enthalpy of the product (HP) is greater than the enthalpy of reactants (HR). As a result, changes in enthalpy (ΔH), namely the difference between the enthalpy of the product with the enthalpy of reactants is positive. So that:
ΔH = HP - HR Activation Energy ΔH> 0
From the graph above, can be seen that ΔH = HP - HR. Because HR is smaller than the HP. So ΔH> 0 Examples of endothermic reaction is a reaction to the melting of ice in a container. Examples of chemical reactions from ice melt events are: Sign (+) at 6.02 kJ on the left arrow indicates that the heat is absorbed by 6.02 kJ.
REACTION ice melts Thus, the reaction can also be written as follows: In reaction to the endoderm, heat (q) absorbed so that the positive enthalpy change (ΔH> 0). The reaction can be illustrated on the chart as well.
EXAMPLES OF REACTION endothermic Other examples of endothermic reactions in everyday life include: - Dissolution of sugar. If the sugar is dissolved, it can be felt there was little sense of cold when the glass is held
The hand was cold when in contact with alcohol - Assimilation
- Photosynthesis - Burning kerosene oil stove
- Flame campfire when camping
The difference between exothermic and endothermic reactions A. Exothermic reaction Exothermic reaction occurs heat transfer from the system into the environment or on the reaction heat is released.
In the exothermic reaction of prices DH = (-)
Example: C (s) + O2 (g) → CO2 (g) + 393.5 kJ; DH = -393.5 kJ B. endothermic reaction Endothermic reaction occurs heat transfer from the environment to the system or to the reaction heat is needed.
In endothermic reactions DH Price = (+)
Example: CaCO3 (s) → CaO (s) + CO2 (g) - 178.5 kJ; DH = +178.5 kJ
Simple understanding of the endothermic reaction 1. Reactions that require heat 2. The temperature of the system C
A + B ----> C - 25 kJ C absorbed heat 25 kJ
r = p - 25 kJ
r <h = "HP"> il ΔH = +
2.1.Reaksi endothermic or Endotermal
Endothermic reaction is a reaction that requires energy or absorb energy from the environment when the reaction occurs, this reaction generally produces dingin.atau temperature endothermic reaction is a chemical reaction that absorbs heat. Heat is taken from the environment so that the enthalpy increases. In endothermic reactions absorb energy systems. Therefore, the enthalpy of the system will increase, meaning that the enthalpy of the product (HP) is greater than the enthalpy of reactants (HR). As a result, changes in enthalpy (ΔH), namely the difference between the enthalpy of the product with the enthalpy of reactants is positive. So that:
ΔH = HP - HR Activation Energy ΔH> 0
From the graph above, can be seen that ΔH = HP - HR. Because HR is smaller than the HP. So ΔH> 0 Examples of endothermic reaction is a reaction to the melting of ice in a container. Examples of chemical reactions from ice melt events are: Sign (+) at 6.02 kJ on the left arrow indicates that the heat is absorbed by 6.02 kJ.
REACTION ice melts Thus, the reaction can also be written as follows: In reaction to the endoderm, heat (q) absorbed so that the positive enthalpy change (ΔH> 0). The reaction can be illustrated on the chart as well.
EXAMPLES OF REACTION endothermic Other examples of endothermic reactions in everyday life include: - Dissolution of sugar. If the sugar is dissolved, it can be felt there was little sense of cold when the glass is held
The hand was cold when in contact with alcohol - Assimilation
- Photosynthesis - Burning kerosene oil stove
- Flame campfire when camping
The difference between exothermic and endothermic reactions A. Exothermic reaction Exothermic reaction occurs heat transfer from the system into the environment or on the reaction heat is released.
In the exothermic reaction of prices DH = (-)
Example: C (s) + O2 (g) → CO2 (g) + 393.5 kJ; DH = -393.5 kJ B. endothermic reaction Endothermic reaction occurs heat transfer from the environment to the system or to the reaction heat is needed.
In endothermic reactions DH Price = (+)
Example: CaCO3 (s) → CaO (s) + CO2 (g) - 178.5 kJ; DH = +178.5 kJ
Simple understanding of the endothermic reaction 1. Reactions that require heat 2. The temperature of the system C
A + B ----> C - 25 kJ C absorbed heat 25 kJ
r = p - 25 kJ
r <h = "HP"> il ΔH = +
endothermic reaction is a reaction that requires or absorbs heat, for example in their daily lives the most convenient way is to melt the ice event, or the manufacture of salt by heating from the sun, the wax is melted.
exothermic reaction is a reaction that occurs when a substance or object release / release of heat, in their daily lives are most easily seen is the condensation events, or the outside of the glasses full of cold water to wet the glass seolah2 leaking, but the air around the glass is a condensed ...
Sabtu, 08 Oktober 2011
ATOM, MOLECULE and ION
what is mean by the atom. molecules and ions ???
ATOM
Atom is a basic unit of matter, which consists of atomic nuclei and negatively charged electron cloud that surrounds it. The nucleus consists of positively charged protons, and neutrons are electrically neutral (except hydrogen-1 nucleus, which has no neutrons). The electrons in an atom bound to the nucleus by electromagnetic force. As well as a set of atoms can bind to each other, and form a molecule. Atom that contain the number of protons and electrons the same neutral, while containing a number of different protons and electrons are positive or negative and is referred to as ions. Atoms are grouped based on the number of protons and neutrons contained in the nucleus. The number of protons in an atom determines the chemical element the atom, and the number of neutrons determines the isotope of the element.
Though the word atom originally meant a particle that can not be cut again into smaller particles, in the terminology of modern science, atoms are composed of various subatomic particles. Constituent particles of atoms are electrons, protons, and neutrons. However, hydrogen-1 has no neutrons. Similarly, the positive hydrogen ions H +.
Atom has no clear outer boundaries, so that the dimensions of atoms is usually described as the distance between two atoms when two atomic nuclei join together in chemical bonds. The radius will vary depending on the type of atom, the type of bonding is involved, the number of atoms in the vicinity, and the atomic spin. [60] On the periodic table of elements, the radius of the atom will tend to increase with increasing periods (top to bottom) . Instead atomic radius will tend to increase with decreasing group numbers (right to left). [61] Therefore, the smallest atom is helium with a radius of 32 pm, when the largest is the cesium with radius 225 pm. [62] these dimensions are thousands of times smaller than the waves of light (400-700 nm), so that atoms can not be seen using a microscope ...
The molecule is defined as a group of atoms (at least two) which bind to each other very strongly (covalently) in a specific arrangement of charged and neutral and fairly stable. According to this definition, different molecules with polyatomic ions. In organic chemistry and biochemistry, the term molecule is used in a less rigid, so that the organic molecules and biomolecules including uncharged molecules were considered.
In the kinetic theory of gases the term molecule is often used to refer to any gas particles without relying on its composition. According to this definition, a noble gas atoms are considered as molecules although these gases consist of a single atom is not bonded.
A molecule may consist of atoms berunsur same (eg oxygen O2), or composed of different elements (eg water H2O). Atoms and complexes connected by non-covalent (eg, bound by hydrogen bonds and ionic bonds) are generally not considered as a single molecule.
Though the word atom originally meant a particle that can not be cut again into smaller particles, in the terminology of modern science, atoms are composed of various subatomic particles. Constituent particles of atoms are electrons, protons, and neutrons. However, hydrogen-1 has no neutrons. Similarly, the positive hydrogen ions H +.
Atom has no clear outer boundaries, so that the dimensions of atoms is usually described as the distance between two atoms when two atomic nuclei join together in chemical bonds. The radius will vary depending on the type of atom, the type of bonding is involved, the number of atoms in the vicinity, and the atomic spin. [60] On the periodic table of elements, the radius of the atom will tend to increase with increasing periods (top to bottom) . Instead atomic radius will tend to increase with decreasing group numbers (right to left). [61] Therefore, the smallest atom is helium with a radius of 32 pm, when the largest is the cesium with radius 225 pm. [62] these dimensions are thousands of times smaller than the waves of light (400-700 nm), so that atoms can not be seen using a microscope ...
MOLECULE
The molecule is defined as a group of atoms (at least two) which bind to each other very strongly (covalently) in a specific arrangement of charged and neutral and fairly stable. According to this definition, different molecules with polyatomic ions. In organic chemistry and biochemistry, the term molecule is used in a less rigid, so that the organic molecules and biomolecules including uncharged molecules were considered.
In the kinetic theory of gases the term molecule is often used to refer to any gas particles without relying on its composition. According to this definition, a noble gas atoms are considered as molecules although these gases consist of a single atom is not bonded.
A molecule may consist of atoms berunsur same (eg oxygen O2), or composed of different elements (eg water H2O). Atoms and complexes connected by non-covalent (eg, bound by hydrogen bonds and ionic bonds) are generally not considered as a single molecule.
IONS
Ions are atoms or a set of electrically charged atoms. Negatively charged ions, which capture one or more electrons, called anions, because he was attracted to the anode. Positively charged ions, which lost one or more electrons, called cations, because they are attracted to the cathode. Ion formation process is called ionization. Atoms or groups of atoms are ionized tikatas marked with n + or n-, where n is the number of electrons lost or gained..
Ion solution is a solution containing ions which can move freely so that it can conduct electricity.
Broadly speaking, in fact I do not understand in studying chemistry. For instance my friends always laugh at me every time I stood in front of the class in the law because it does not memorize the periodic system, or are unable to resolve the problem of the equation. I confess I think the lesson is slow or its trend word "Lola" but behind it there is my interest to learn it. Even now I still have not been able to work on the issues discussed equation. First I was naughty, did not want to know about the subject especially with chemicals. Now I've sat in a chair that would toss my name with the soul of chemistry. I hope I'll be eager to love and learn with fun chemistry. I hope my teachers are not angry and want to teach me, because I really need their help. I love chemistry, Hopefully ................*_^
Broadly speaking, in fact I do not understand in studying chemistry. For instance my friends always laugh at me every time I stood in front of the class in the law because it does not memorize the periodic system, or are unable to resolve the problem of the equation. I confess I think the lesson is slow or its trend word "Lola" but behind it there is my interest to learn it. Even now I still have not been able to work on the issues discussed equation. First I was naughty, did not want to know about the subject especially with chemicals. Now I've sat in a chair that would toss my name with the soul of chemistry. I hope I'll be eager to love and learn with fun chemistry. I hope my teachers are not angry and want to teach me, because I really need their help. I love chemistry, Hopefully ................*_^
Broadly speaking, in fact I do not understand in studying chemistry. For instance my friends always laugh at me every time I stood in front of the class in the law because it does not memorize the periodic system, or are unable to resolve the problem of the equation. I confess I think the lesson is slow or its trend word "Lola" but behind it there is my interest to learn it. Even now I still have not been able to work on the issues discussed equation. First I was naughty, did not want to know about the subject especially with chemicals. Now I've sat in a chair that would toss my name with the soul of chemistry. I hope I'll be eager to love and learn with fun chemistry. I hope my teachers are not angry and want to teach me, because I really need their help. I love chemistry, Hopefully ................*_^
Jumat, 07 Oktober 2011
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