How do i calculate the percent by mass of each element?
956100
You will need to know that when you calculate a percentage of anything, it is kind of like a fraction, except that the denominator is 100.\n\nFor example, you have 7 sticks. 3 of them are red, 2 of them are yellow and the other 2 are blue. To get a percentage of the number of red sticks:\n\n(no of red sticks /  total no of sticks) x 100%\n\n...and that is how you get your percentage.\n\nOnce you have understood that this question should be quite simple. Sodium sulfite is Na2SO3.\n\n\nFirst you have to calculate the masses of all the elements in this compound.\n\nmass of Na\n= 2 x 23\n= 46\n\nmass of S\n= 1 x 32\n= 32\n\nmass of O\n= 3 x 16\n= 48\n\ntotal mass of Na2SO3\n= 46 + 32 + 48\n= 126\n\n\nHence, using the same concept,\n% of Na by mass\n= (46 / 126) x 100%\n= 36.5% (3 s.f.)\n\n% of S by mass\n= (32 / 126) x 100%\n= 25.4% (3 s.f.)\n\n% of O by mass\n= (48 / 126) x 100%\n= 38.1% (3 s.f.)\n\n\nHope you understand now! Cheers :D
899322
First find how many moles of each reactant you have\n\nmoles BaI2 = M*V= 1.35*0.055\nmoles MgSO4 = M*V= 1.2*0.0476\n\nThe reaction is \nBaI2 + MgSO4 ->BaSO4 + MgI2\n\nthe stoichiometry is 1:1, so you should have equal moles of the two reactants. In your case however one of them is in excess. So you will have to calculate the yield based on the limiting reagent.\n\nSince the stoichiometry is also 1:1 for BaSO4 and the limiting reagent you should have moles of BaSO4 = moles of the limiting reactant. But moles=mass/MW => mass= moles*MW\nYou have calculated the moles, find the MW of BaSO4 and you'll get the theoretical mass of BaSO4 that would come from 100% reaction.\nThe percent yield is (actual mass/theoretical mass)*100%
553400
take the mole fraction and multiply by the atomic weight of each which you can find on the periodic table. For carbon, it would be 12 x .04 = .48 Once you have all three, sum them and divide each by this sum. So, say you find Ch and I for the other two. Then the percentage by weight of Carbon would be the number you got for Carbon (.48) divided by (.48 + Ch + I).\n\nTo double check, your weight percentages should all add up to 100%.
66748
Well this is easy, what you have to do is put in the values as follows:\n\nA1 = 10000\nA2 = =(A1*0.25)+A1\nA3 to A5 jus drag the column in A2, this will compute the percentage of each column just above the column with the formula, and give the result you want.\n\nI hope this is the solution u were looking at.\n\nRegards\nChris
62338
multiply 220 times 0.564 then divide by 31. That will give you the number of P atoms in the formula(the subscript). \nmultiply 220 times 0.436 then divide by 16. That will give you the number of O atoms.\nYou can do the same for problem two but use the right molecular mass and the right percents.
891286
Percentage composition means calculating the percentage (by mass) of an atom in its molecule. For instance, we would say:\n\n"Calcium Hydroxide (Ca(OH)2) is x% Calcium, y% Oxygen, and z% Hydrogen"\n\nTo find the percentage composition, first find the total mass of 1 mole of the molecule:\n\nFor Ca(OH)2, there is 1 Ca atom, 2 O atoms, and 2 H atoms. The atomic masses are as follows:\nCa = 40.08 g/mol. \nO = 16.00 g/mol\nH = 1.01 g/mol\n\nThe atomic mass of 1 mol of Ca(OH)2:\nCa + 2*O + 2*H = 40.08 + 2*16.00 + 2*1.01 = 74.1 g/mol\n\nTo find the percentage of Ca, divide the mass of Ca in the molecule by the total mass of the molecule:\n\n%Ca = 40.08 / 74.1 = 0.54 = 54%\n\nDo the same thing with O and H, but remember that there are TWO molecules of O and H in each molecule of Ca(OH)2:\n\n%O = 32 / 74.1 = 0.43 = 43%\n\n%H = 2.02 / 74.1 = 3%\n\n\nNow, repeat this process with the other four:\n\nNaHCO3 = Na + H + C + 3*O = 22.97 + 1.01 + 12.01 + 3*16 = 83.99 g/mol\n%Na = 22.97 / 83.99 =  0.27 = 27%\n%H = 1.01 / 83.99 = 0.01 = 1%\n%C = 12.01 / 83.99 = 0.14 = 14%\n%O = 48 / 83.99 = 0.57 = 57%\n\nCaO = Ca + O = 40.08 + 16.00 = 56.08 g/mol\n%Ca = 40.08 / 56.08 = 0.71 = 71%\n%O = 16.00 / 56.08 = 0.29 = 29%\n\nCaCO3 = Ca + C + 3*O = 40.08 + 12.01 + 3*16.00 = 100.09 g/mol\n%Ca = 40.08 / 100.09 = 0.40 = 40%\n%C = 12.01 / 100.09 = 0.12 = 12%\n%O = 48.00 / 100.09 = 0.48 = 48%\n\nAl2(SO4)3 = 2*Al + 3*S + 12*O = 2*26.98 + 3*32.07 + 12*16.00 = 342.17 g/mol\n%Al = 53.96 / 342.17 = 0.16 = 16%\n%S = 96.21 / 342.17 = 0.28 = 28%\n%O = 192.00 / 342.17 = 0.56 = 56%\n\nI hope this helps!
316912
well, % is the number per one hundred counts. ppm is the number per one million counts.\n\nSo, multiply by 10,000.\n\n10% = 10/100 = 100,000/1,000,000
764912
If I understand correctly what you need then this is what you do:\n(by the way we will take He as 83.7 because it is over 100% other wise.)\nmultiply the molecular or atomic weight of each species by the fraction (percent divided by 100).\n\nMW(CO2) = 44\nMW(N2) = 28\nAW(He) = 4\n\n44*0.11 + 28*0.053 + 4*0.837 = 9.67 g/mol\n\nThis is the equivalent "molar mass" of the mixture.
860730
Multiply moles by the molecular weight (grams per mol) to get mass (grams).
45248
Take your calculator for any similar problem and divide, in this case, 60 by 75 and multiply by the decimal result by 100 and you will have a percentage. This works for all numbers. Take for example what is 19 of 20. Divide 19 by 20 and multiply time 100 and you will have 95%. This is how it is done.
33642
Use the periodic table to find the atomic mass of the element and subtract from this the atomic number.  \n\nThe atomic mass is equal to sum of proton and neutrons, and the atomic number is the number of protons an atom has.  Electrons have such a small mass that they don't really have any noticable effect on the atomic mass.\n\nEx: Oxygen (atomic mass - 16, atomic number - 8)\n\n16 - 8 = 8, therefore the number of protons is equal to 8
881707
Determining the mass is trivial: just weigh the block.  For the density, you will need to know the volume, which will require some measuring with a ruler.  Then divide the mass by the volume for your answer.
29071
Well, look in the periodic table of the elements and find the molecular weight. The molecular weight tells you how many grams are in one mole of that element. Once you know the amount of grams that correspond to 1 mole, you do the math.\nGood luck!
71598
Average calculated by adding all the elements then dividing the sum of the elements by the number of elements
897845
take 35-3, which is 32.  then divide 32 by 35.  you'll get a decimal answer,  move the decimal to the right 2 spaces and that's your percent
455395
multiply by 100, put a percent after it (percent=per 100)
385547
Percent Yield= (Actual yield divide by theoretical yield)*100\n\n\nsolve for Actual yield:\n\n\npercent yield= 92%/100=.92\n\n\n  molar mass of WO3 = 231.85g/mol\n\ntheoretical yield =   3.72g divide by 231.85g/mol = .016mol WO3\n\n\nActual yield = X\n\n\nx =  .016mol WO3*.92\n\n= .0147mol  WO3