Copper is one of a group of metals called the coinage metals. How many atoms of copper (Cu)are in a pure copper coin weighing 12.0 g?Is it.....A) 0.187 x 10^23 atomsB) 1.13 x 10^ 23 atomsC) 0.0313 x 10^23 atomsD) 1.10 x 10 ^23 atoms.....Explain how u got it please! Thank You!
It is D. First you need to divide the weight of the coin by the molecular weight of copper to find the number of moles in the coin. 12 divided by 65.39 g Cu is approx 0.18. avogadros number is the number of atoms per mole, so you just multiply the number by 6.022 x 10^23 it is 1.105 x 10^23
12.0 g of Copper / 63.5 grams of copper per mol times (6.022 e23) Lemme get a calculator. 1.14 e23 atoms. I don't know why your teacher has 1.13 and 1.10... That's wayy too similar (think about 110 with 21 zeros vs 113 with 21 zeros). Especially with rounding differences. But A and C aren't correct because that's not proper scientific notation. But anyways, the answer is B.
12 grams of pure carbon (atomic mass 12) has 6.022?10?? atoms in it. Copper has atomic mass of 63.5, thus 6.022?10?? atoms of copper weighs 63.5 grams. 12.0 g is about one-fifth of 63, so we should expect that the answer should be about one-fifth of 6.022?10?? atoms, or choice b or d. So calculate: [6.022?10??]?[12.0g / 63.5g] = 1.138?10?? atoms which is close enough to choice B to make it correct. B = final answer.
