It's regarding the Avogadro's law. like 23gm of sodium is one mole while 23amu of Na is one atom of it.
136297
That's the definition of the Molar mass, yes.
431084
number of atoms (of each element) on one side equals the other side.
375090
For the first one, multiple the number of moles by the molecular mass of Helium.  Helium is mono-atomic (one atom per molecule) so the atomic mass of Helium is used:\n\n4.56 moles * 4.003 g/mol = ? (you can at least do the math)\n\nFor the second part, each mole of pure substance contains Avogadro's number of molecules (or atoms for an element).\n\nThe number of moles of Zinc is the mass divided by the atomic mass (also called the atomic weight).  For Zinc this is 65.38 g/mol:\n\n12 g / 65.38 g/mol = number of moles of Zinc.\n\nEach mole contains 6.022 * 10^23 atoms of Zinc, so just multiple the number of mole above by 6.022 * 10^23 atoms/mole to get your answer.
647551
2NaCl+H2SO4=Na2SO4+2HCl\n2NaBr+H2SO4=Na2SO4+2HBr\none mole of NaCl weighs 59 gm\none mole of NaBr weighs103gm\none mole of Na2SO4 weighs 142gm\nusing the above you can calculate
553750
1 litre (1000 ml) of 1 M solution of NaCL contains 23 + 35.5 gms =58.5 gms (ie 1 molecular wt of sodium chloride in gms dissolved in 1 lit of solution)\n\nHence 1 lit of 0.360 M solution  will contain 0.360 X 58.5 gms or 21.06 NaCl (Sodium Chloride) \n\nTo find out exact vole in ml which contain 21.14 find volume by this formula 2.14 divide by 21.06 multiply 1000 , (ie 2.14/21.06 * 1000 ) 101.6 ml\n\nPS\nbasic assumption is 0.360 M indicates .360 Molar solution. \n(ie: M stands for Molar)
227826
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.
98294
Tommy was right as far as Mg & Ca are concerned.  Na is a Group 1 metal and is more reactive than either because it's 3s1 structure is an incomplete atomic orbital, whereas Mg (3s2) and Ca (4s2) have a certain stability from being a complete electron pair.
74570
each one exerts 623N so overall it exerts 3742N.\n\ni dont care if its wrong (im too lazy to actually try to figure it out properly and check it n stuff)
350524
ANSWER: 0.482 M\n\n\nEXPLANATION:\n\nM = mol solute / L soln\n\nTherefore, you need to find the mol of solute and L of soln to find M.  \n\nTo find mol solute:\n10800mg Na(1g Na/1000mg Na)(1mol Na/22.99g Na) = 0.4698mol Na\n\nTo find L of soln:\n1kg soln(1000g soln/1kg soln)(1ml soln/1.025g soln)(1L soln/1000ml soln) = 0.9756L\n\nUsing the two values found plug in to M = mol solute / L soln\n\n0.4698mol Na / 0.9756L soln = 0.482 M
454646
At room temperature and pressure one mole (6 x 10^23 particles/atoms/molecules) of a gas fills 24 dm^3 (Litres).\n\nThis means that in every cubic centimeter (one millilitre) of air there are 2.5 x 10^19 molecules.\n\nIf we forget about the rapid movement and think how many static molecules this means in each dimension we find that each 1-dimensional 1-cm long line contains 2,924,017 molecules (let's say 3 million to keep things simpler).\n\nOver 70% of air is Nitrogen and the length of an N2 molecule is about (keeping things simple) 100 pm (picometers; 10^-12 m) so 3 million molecules take up 300 million picometers or 300 micrometers (following conversion)\n\nThere are 10,000 micrometers in a centimeter so the molecules only 3% of the available distance.\n\nIf all 3 million molecules were equally spaced they would be approximately 3.3 nm (nanometers; 10^-9 m) apart.\n\nA division of the molecular length (100 pm) by the separation (3.3 nm) shows that they are about 33 molecules length apart.\n\nNow I've made plenty of assumptions here. I'm more than happy for people to point out where I've gone wrong (if I have). Please PM me.
559813
A mole is simply a way of saying theres a biiiiig number of atoms involved. Just think of it as say, the word "billion". I have a "billion" atoms. What is a billion? Well a billion is 1,000,000,000. What is a mole? Well a mole is 6.022*10^23. If theres 1.5 billion molecules in a sample, there are 1,5000,000,000 molecules in that sample. If there is 1 mole of molecules in a sample, there are 6.022*10^23 molecules in that sample. Simple as that, it's just a very large number.\n\nIf have you have a formula that says for example: 1 NaOH + 1 HCl -> 1 NaCl + 1 H20, you can look at it with moles in mind. For every 1 mole of Sodium Hydroxide and 1 mole of Hydrochloric acid, you will produce 1 mole of sodium chloride and1 mole of water. It basically means that if you add 6.022*10^23 molecules of sodium hydroxide to the same number of hydrochloric acid, you'll produce 6.022*10^23 molecules of sodium chloride and water.
376235
The Mole was not so much "discovered", but arbitrarily created. (Much like any other unit of measure). All this means is that scientists agreed upon a specific amount that will represent 1 mol of a substance. This amount was related to every element based on its average atomic mass value, which in the case of moles is named the molar mass. Each element has a different molar mass, which is why 12g of carbon is one mole, whereas 12g of oxygen is only 0.75 moles.\nOne mole represents a value of 6.022x10^23 atoms of elements, or 6.022x10^23 molecules of a substance. This number is Avogadro's number, and is the "number" behind a mole.\nAs this is an SI unit (Système Internationale) I believe this concept was first introduced by French Scientists.
548801
M = moles/L\nso, 0.220M = 0.220 moles per liter and there are 2 liters so there are...\n0.440 moles of Mg(NO3)2\n\nBUT... notice that there are 2 ions of NO3 for each molecule, so double it again and get 0.880 moles of NO3
441163
To get the no. of moles of sodium in each serving, you must use the equation: no. of moles = mass / relative molecular mass\nThe realtive molecular mass of sodium (Na) is 23 (from periodic table of elements) \nSo for the waffles, the 480mg must first be converted to grams. There are 1000 mg in 1g so there are 0.480g of sodium in the waffles. Therefore the no. of moles of Na in the waffles is:\nno. of moles = 0.480g / 23g = 0.02moles\n\nFor the gatorade, the 110mg is converted to grams also, which is 0.110g. Therefore the no. of moles of Na in gatorade is:\nno. of moles = 0.110g / 23g = 0.0048 moles\n\nLikewise for the juice, the 35mg is converted to grams which is 0.035g. The no. of moles of Na in this is:\nno. of moles = 0.035g / 23g = 0.0015moles\n\nTo find the amount of atoms of sodium in each of the samples we use the following equation:\nno. of atoms = no. of moles x 6x10^23 x no. of atoms per entity\n\n(6x10^23 = Avogadros constant)\nno. of atoms per entity = 1 (because there is only one atom of Na in Na)\n\nTherefore, in the waffles the no. of atoms is:\nno. of atoms = 0.02 x 6x10^23 x 1\nno. of atoms = 1.2x10^22\n\nFor the gatorade, the no. of atoms is:\nno. of atoms = 0.0048 x 6x10^23 x 1\nno. of atoms = 2.88x10^21\n\nFor the juice, the no. of atoms is:\nno. of atoms = 0.0015 x 6x10^23 x 1\nno. of atoms = 9x10^20\n\nFinally to find out how many servings you would need to get your full recommended daily allowance (RDA), you must do the following:\n\nWaffles: 0.48g is 20% of your RDA\n               0.024g is 1% of your RDA\n               2.4g is 100% RDA\n               Therefore you would need 2.4g / 0.48g = 5servings\n\nGatorade:0.110g is 5% of your RDA\n                0.022g is 1% of your RDA\n                2.2G IS 100% of your RDA\n                Therefore you would need 2.2g / 0.110g = 20servings\n\nJuice: 0.035g is 1% of your RDA\n          3.5G IS 100% of your RDA\n          Therefore you would need 3.5g / 0.035g = 100 servings\n\n\nHope Ive been of help to you!!!\nIf you've anymore questions just ask!
361137
number of moles of NaCl = Mass/Mr\nalso\n\nNumber moles NaCl = molarity X vol(cm3)/1000\n\ntherefore\n\nMass/Mr = molarity X vol (cm3)/1000\n\nSo, if you rearrange the above:\n\nMass NaCl you need to dissolve = Mr X molarity X vol(cm3)/1000\n\nIn the question molarity is 2M and the volume is 300cm3.  I'll let you figure out the Mr of NaCl (just add together the relative atomic masses of Na [23] and Cl[35.5] and arrive at your answer.\n\nHope it helps.
70810
Gain one/two electron(s):\n\nIf an atom or ion acquires another electron in a chemical reaction, it has gained an electron.  ditto for two electrons.\nExample: S has 16 electrons.  If it gains one electron it becomes a S- ion.  If it gains two electrons, it becomes a S-2 ion.\n\nSteal one/two electrons:\nIf an atom or ion looses an electron in a chemical reaction, it had to go somewhere.  That "somewhere" will be to another atom/ion.  So, the receiving atom/ion could be said to have stolen the electron.  Same goes for reactions involving two electrons.\nExample: Na reacts with Cl to produce NaCl.  Cl "steals" an electron from Na, creating Na+ and a Cl- ions.\n\n"Never ever react electron"\nI have never ever heard this phrase.  Maybe it refers to a species (atom or ion) that does not participate in the reaction.  It's valence electron(s) would not react.
330317
Jaleesa, I think that you can use the same principle that I explained in the earlier question. The Sodium ion has fewer electrons and fewer shells, and is thus smaller than the potassium ion. But I think you should do the rest of your homework yourself.