Scientists at a congress in Karlsruhe (Germany) in the 1860th year made the decision to call atom the smallest indivisible particle of substance which is the carrier of its chemical properties. Amount of atoms even in the tiniest, almost not distinguishable with the naked eye, a substance sample not just huge – grandiose. And whether it is possible to count somehow how many atoms contain in any given amount of substance?
Instruction
1. Review such example. You have some copper subject, for example, a piece of a thick wire or a plate. How to define how many atoms of copper contain in it? For simplification of the decision it is admissible that it is pure copper without any impurity and without oxides covering its surface.
2. First of all, weigh this subject. Best of all - on laboratory scales. Let's assume, its weight – 1270 grams.
3. Now look in Mendeleyev's Table. The atomic mass of copper (rounded) – 63.5 and. e. m (atomic units of mass). Therefore, the molar mass of copper – 63.5 grams/mol. From this you will easily find that the studied sample contains 1270/63.5 = 20 moths.
4. Calculate amount of atoms in a sample of copper by a formula: m*NA where m is molal quantity, and NA is so-called number of Avogadro. It corresponds to quantity of the smallest particles of substance – atoms, ions, molecules - in one its pier and is equal 6.022*10^23. In your case it is about atoms. Having increased 20 by Avogadro's number, receive the answer: 1.204*10^25 - there are so much copper atoms in a sample.
5. Let's a little complicate a task. It is known that copper because of the softness and plasticity is often used not in pure form and as a component of alloys with other metals giving it hardness. For example, the well-known bronze – copper alloy with tin.
6. You have a bronze detail made of alloy which part 20% of tin and 80% of copper are. Detail weight – 1186 grams. How many atoms does it contain? First of all, find the mass of components of alloy: 1186 * 0.2 = 237.2 grams of tin; 1186 * 0.8 = 948.8 grams of copper.
7. By means of Mendeleyev's Table find the molar mass of tin – 118.6 grams/mol. Therefore, contains in alloy 237.2/118.6 = 2 asking tin. Means, 948.8/63.5 = 14.94 asking copper. For simplification of calculations, it is possible to take amount of copper for 15 moths, the error will be absolutely small.
8. Further make calculation on the following formula:(15+2) *6.022*10^23 = 1.02*10^25. So many atoms contain in the available bronze sample.