Why is the no. of moles of a substance equal to mass by molecular mass?
960826
I will assume you mean "mass divided by molecular mass." The molecular mass is, by definition, the mass of one mole of a substance. Thus, if you take a given mass and divide it by the molar mass, you will get the number of moles.  A good way to do this is to use demensional analysis, where you start with you mass (x grams) use your molar mass as the conversion (Z moles/ygrams) and multiply the two so that the grams cancel, leaving you with moles.
866680
OK - chemists are basically lazy (that's why we use symbols for elements and formulas for compounds; we don't really like to write that much.)\n\nThe mole is a shortened way to indicate a really big number.\n\nIf I said to you, 1 dozen, you would know I am talking about 12 of something (doesn't matter what, its still 12).\n\nIf I said to you, 1 pair, you would know I am talking about 2 of someting (doesn't matter what, its still 2)\n\nIf I said to you, 1 mole, you would know I am talking about\n602200000000000000000000 of something (doesn't matter what, its still that much.) This is usually written as 6.022 x 10(23)\nbecause we are not about to keep track of all those zeroes.  If I told you your allowance was 1 mole of dollars you would be very rich because you would have 6.022 x 10(23) dollars. (Remember me in your will).\n\nAtoms are too small to see so we have to work with A LOT of them and everyone has agreed on a "standard" number of atoms, 1 moles worth, also called "Avogadro's number".  You could have less than that (0.5 moles, 0.456 moles) or more (10 moles, 540 moles etc.) but the "standard" for comparison is 1 mole.\n\nSo, for your project, figure out how many "whatevers" it takes to go around the world and then divide that number by 6.022 x 10(23) and you will know how many moles of your "whatever" you need.
751778
1 mole of an element= 6.022x10^23 atoms\n1 mole of an element weighs the molecular weight of the element in grams
290716
Unless a equation is properly balanced the amount of product and reactant will not be the same, I suppose this is like a recipe where u get the proper number of ingredients(moles) and mix to together to give the you the proper number of products.
529016
The "amount" of each compound present in the reaction.  While most will tell you that it technically is in terms of "moles", it can just as easily be thought of as a recipe.  \nIf you wanted to create a particular substance in the lab, these amounts would give you an idea of the amount of reactants needed to synthesize the end material.
494602
density of substance is equal to the ratio of mass of the substance to the volume of the substance.\n \ndensity=mass/volume
408650
a mole is the amount of a substance equal to its molecualr weight or 6.02 x 10^23 particles.  Molarity is the number of moles dissolved in a litre of solvent....if memory serves
241737
The rate at which gases diffuse is inversely proportional to the square root of their densities. \n\nSince volumes of different gases contain the same number of particles (see Avogadro's Hypothesis), the number of moles per liter at a given T and P is constant.  Therefore, the density of a gas is directly proportional to its molar mass (MM).
728109
Number of moles = mass/formula mass for a pure acid.\n\nBut acids in solution have a different equation:\n\nmoles = volume x molarity/1000\n\nThe volume in the above equation is in cm3.
196844
A Mole is 6.023X10^23 of what ever you have.  Specifically, it pertains to atoms.  For example, if you have a mole of Helium atoms then you have exactly 6.023X10^23 of them.  It's like saying you have a "dozen" eggs which means you have twelve of them.  Well, if you went to the store and purchased a "mole" of eggs, then you would have 6.023X10^23 of them.  That's a bunch of eggs!
924159
It depends on what you have, if you know the mole of the molecule, you can determine the mass by converting molar mass (g/mol) into mass (g). The mole of the molecule can be found on the periodic table, but first you need to know the molecule formula of the compound. Then add it up.
358467
because electrons mass is insignificant to the mass of the nucleus of the atom. omitting the electron mass is prctical because there is soo much space between electrons and other atoms in a molecule at any given time that 99.9% of the density that effects the behavior of a moving molecule come from the nucleus itself.
994333
Molar mass is the weight of a compound at a constant number of molecules.\n\nWhere are many uses in which it would be usefull, but for a non-chemist it would be meaningless. \n\nTher are numberous example I could give you where it would be usefull but all of these relate to chemisty. I will therefore make on up.\n\nSay someone wanted to destory a compound that was dangerous but that the agent to use was expensive or could not be keep for more than 24 hours. The compound that was to be destoried reacted on a 1 mole to 1 mole ratio. It is known that the compound we want to get rid off had a molar mass of 32 g/mol\nand there was 16 grams of the compound. So using the weight and molecular mass we can work out that the number of moles we have is 0.5. OK now nowing that our agent reacts on a ratio of 1:1 we need 0.5 moles of our agent. But our agent has a molecular mass of 64 g/mol, so the weight we need to use is 0.5 moles x 64 g/mol = 32 grams.
1138448
Look on a periodic table.\n\nIt should be listed below the atomic number as a decimal value.  The mass number is an average mass (in atomic mass units) of an element, based on different isotopes.  It equals the number of protons + the number of neutrons in the nucleus.
930413
6.37 moles of any molecular substance just contains 6.37 times Avogadro's number of molecules, because a mole of matter always contains a mole of particles, that is, Avogadro's number many.  6.37*6.022 x 10^23 = 3.84 x 10^24.
497438
The atomic number is equal to the number of protons.\nThe mass number is equal to protons plus neutrons.\n\nThe difference between those two numbers would equal the number of neutrons.
988363
Yes indeed :)\nA mole is a term used by chemists to count. That is correct count. You have no doubt heard of the formula for water. H2O. What this means is 2 atoms of Hydrogen + 1 atom of Oxygen gives you one molecule of water.\n That is simple enough. Of course nature being nature is not quite so nice. If one just looked at that formula and went ok all I need is for example 2 pounds of Hydrogen and 1 pound of Oxygen then I get I water right ? nope. You have started to use what chemists call units. and not all units are equal. True one pound  is in fact one one pound. The equation above( H2O) counts atoms not pounds.  And each atom weighs a different amount. So 1 pound of hydrogen will contain a different number of atoms then will 1 pound of Oxygen.\n\nChemists get around this problem using the concept of the mole. Also called Avrogrado's number. it is a very big number. 6.023 x 10^23.\n\nWhat Avrogrado discovered was that if you have that many atoms of a particular element you also got its atomic weight. Now you had some thing you could measure in a lab.\nFor example. the atomic weight of Hydrogen is 1.0 grams. So that means if I have 1.0 grams of Hydrogen I also have 6.023 x 10 ^23 atoms of hydrogen. Oxygen has an atomic weight of 16 grams. So if you have 16 grams of Oxygen then you have 6.023 x 10^23 atoms of oxygen. As you can see a mole is simply a way of saying  6.023 x 10^23 easly.\n\nIn terms of making water\n\nWe now have\n2 moles of Hydrogen ( 2 grams of Hydrogen) or 2x(6.023x10^23)atoms of Hydrogen + 1 mole of Oxygen( 16 grams of Oxygen) or 6.023 x10^23 atoms of Oxygen = 1 mole of water or 1mole H2O or 6.023x10^23 Water molecules.\n\nSo the formula for making water or any other substance relies on counting the number of moles. You can of course have a mole of anything since the mole mearly represents the number 6.023x10^23\n\nIf you simply want to know the number of moles you have in any given weight you do the following\n\nWeight you have/Atomic weight or the Weight per mole = # moles