Documents

Summary of Chemistry Textbook - Section 4.1 the Mole Concept and Avogadro's Constant

Categories
Published
of 2
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
Share
Description
IB Chemistry notes
Transcript
  Summary of Chemistry Textbook: Section 4.1  –   The Mole Concept and Avogadro’s Constant -   A relative scale   is one in which all measurements are compared to one standard or reference measure -   Relative scales have no units  –  they are merely comparisons of one quantity with another -   Advantage of relative scales is that very large or very small numbers can be compared more easily -   To generate the relative scale of atomic masses, chemists chose the most abundant isotope of the element carbon, the carbon-12 isotope ( 12 C), relative mass of exactly 12 units -   Reasons for choosing carbon:    Carbon is very cheap and is widely available    It is relatively easy to isolate and purify this isotope    Carbon is not toxic in any way -   Mass of 12 units mirrors the mass number of the isotope -   Relative atomic mass will closely parallel the number of these fundamental particles in the nucleus of the element -   Thus, the lightest of all elements, hydrogen, will have a relative atomic mass of close to 1 -   A mole   is defined as the amount of substance that contains as many elementary particles as there are atoms in precisely 12 grams of the carbon-12 isotope -   Actual number of atoms determined as approximately 6.02 x 10 23  -   Number is known as Avogadro’s constant , (symbol, L ) -   It is important to recognise that a mole is simply a number, just as a dozen is equal to 12 or a gross is equal to 144 L  = 6.02 x 10 23  mol -1  -   Atoms are so small that it is impossible to see an individual atom Calculating numbers of particles -   If you are asked to calculate a number of particles, the you are calculating the quantity represented by N  and you will obtain a number with no units -   Asked to calculate an amount   of substance, then you are trying to find a number    of mole  of the substance -   This is the quantity represented by n  and wi ll have the units ‘mol’      Where n = number of mole (amount), N = number of particles and L = Avogadro’s constant   SECTION 4.1 EXERCISES 1.   Calculate the number of mole of the stated particles in 1.00 mole of sulphuric acid. a)   Atoms of sulphur  –   1  b)   Atoms of hydrogen  –  2 c)   Atoms of oxygen    –  4  d)   Total number of atoms  –  7  2.   Calculate the number of mole of the stated particles in each of the following. a)   Magnesium ions in 1.25 mole of magnesium nitrate  –  1.25    b)   Sodium ions in 3.25 mole of sodium sulfate    –  2 x 3.25 = 6.50 mole of sodium ions  3.   Calculate the number of mole of the states particles in each of the following. a)   Carbon atoms in 2.00 mole of propane  –  2.00 x 3 = 6 mole of carbon atoms  b)   Carbon and hydrogen atoms in 1.25 mole of pentane  –  1.25 x 17 = 21.25  4.   Determine the number of particles, present in the following: a)   3.50 mol of ammonia molecules  –  n = 3.50 L = 6.02 x 10 23  Therefore; 3.50 x 6.02 x 10 23  = 2.10 24   b)   3.22 x 10 -3  mol of manganese nitrate n = 3.22 x 10 -3  L = 6.02 x 10 23 Therefore; 3.22 x 10 -3  x 6.02 x 10 23  = 1.94 x 10 21 5.   Calculate the amount of substance in mol present in each of the following. a)   1.44 x 10 24  atoms of neon = 2.39 mol of atoms b)   1000 atoms of mercury = 1.661 x 10 21  mol of atoms
Search
Tags
Related Search
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks