7. Borazon, one crystalline form of boron nitride, BN, is very likely the hardest of all substances. If one sample contains 3.02 X 1023 atoms of boron, how many atoms and how many grams of nitrogen are also in this sample? 8. If iodine is not in a person's diet, a thyroid condition called goiter develops. Iodized salt is all that it takes to prevent this disfiguring condition. Calcium iodate, Ca(IO3)2, is added to table salt to make iodized salt. How many atoms of iodine are in 0.500 moles of Ca(IO3)2? How many grams of calcium iodate are in 0.005mol of Ca(IO3)2?
1) Just use your molar ratios, there is 1B per 1N. So for number of atoms, it's: 6.02x10^23 atoms B x (1atom N/1atom B) = 6.02x10^23atoms N Then to find the mass, just use the molar mass of nitrogen, 14.011g/1mol: 6.02x10^23 atoms N x 14.011g N / 6.02x10^23mol N = 14.011g N (remember that 1 mole = 6.02x10^23 particles/atoms/whatever, just like a dozen is always 12 of something.) 2) To find the atoms of Iodine, use your molar ratios. There are 2atoms I per 1compound Ca(IO3)2. So, .5mol Ca(IO3)2 * (6.02x10^23compounds Ca(IO3)2 / 1mol Ca(IO3)2) * (2atoms I / 1compound Ca(IO3)2) = 6.02x10^23 atoms I To get the mass, just use the molar ratios of Ca(IO3)2, which is 389.878g/1mol (you just add up all the molar masses of each element). Then: .005mol Ca(IO3)2 x (389.878g Ca(IO3)2 / 1mol Ca(IO3)2) = 1.94939g Ca(IO3)2
Sure there are. In #7, the equation is BN (1Boron and 1Nitrogen) and in #8 it is Ca(IO3)2. It's actually a molecular formula since the problem doesn't have a product.
7) convert boron to moles: (3.02 X 1023) / (6.022 x 10^23) = moles of boron since its BN then moles boron = moles nitrogen to find atoms you multiply the moles of N to 6.022 x 10^23 so thats the same # atoms as boron so take the moles of boron/nitrogen and use the molar mass to convert to grams: moles of nitrogen x 14.007 = grams of nitrogen 8) you should be able to figure out its the same as number 7 basically
