Solutions1Solution:Do not get hung up thinking “Hey, we never did one like this before!” Think in terms ofrelationships.To FindYou needatomsmoles andNAmolesmass and atomic massSo the problem becomes more clear once you identify the relationships.atomsmolesNAatomsgramsatomic massNASo now we know what we are looking for. We need the mass of the iron metal! Let’s see ifwe can find that from the density. Density has units g/cm3. For iron the density is 7. 9g/cm3. How can we use this to get grams? Let the units guide you. To get the mass of ironmetal it looks like we just need to multiply density by cm3which is a unit of volume.mass g7. 9 g/cm3sphere volume cm37. 9 g/cm3434.0 in22.54 cm/in34338. gDon’t forget the inch to cm conversion! Now that we have the mass we can find moles andatoms. We have already written the formula we need.atomsgramsatomic massNA4338. g55. 85 g/mol6.0221023atoms/mole4. 6781025atoms2Solution:The thin sheet looks like a cylinder that is 1 atom high. The volume isVr2h1. 1 cm3where h is the diameter of the atom. We are asked to find the diameter of the thin sheet.d22h1. 1 cm3The thickness of the thin metal sheet is equal to thediameterof the atom.h2. 78 Å
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