WoC Ch 6.2 to ___. Chemical Composition. The balanced chemical equation for the reaction of solid carbon and gaseous oxygen to form gaseous carbon dioxide is as follows;. C (s) + O 2(g) CO 2(g). Objective: Understand atomic mass and its experimental determination .
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C(s) + O2(g) CO2(g)Objective: Understand atomic mass and its experimental determination
The mass of a single C atom is 1.99 x 10-23g
To avoid using terms like 10-23 when describing the mass of an atom, scientists have defined a much smaller unit of mass called the atomic mass unit, which is abbreviated amu. In terms of grams,
1 amu = 1.66 x 10-24
What are isotopes?
What are the isotopes of carbon?
Carbon 12, carbon 13, and carbon 14
All samples of carbon contain these isotopes, always in the same proportions. We have to use an average mass for the carbon atoms.
For carbon, the average atomic mass is 12.01 amu. This means that any sample of carbon from nature can be treated as though it were composed of identical carbon atoms, each with a mass of 12.01 amu.
Mass of 1000 natural carbon atoms
= (1000 atoms) (12.01 amu/atom) = 12,010 amu
In scientific notation?
1 carbon atom = 12.01 amu
1 carbon atom is the conversion factor
You know that a mole of anything is Avogadro’s number of anything. During the m&m activity, you determined the volume of a mole of m&m’s and compared that to a volume of something on or relative to earth.
The Pacific ocean could almost be filled with a mole of m&m’s.
2.9 moons would hold a mole of m&m’s
You could walk from California to Australia on m&m’s
The molar mass of any substance is the mass (in grams) of 1 mole of the substance.
Calculate the molar mass of sulfur dioxide, carbon tetrachloride, and sulfuric acid.
(1 x 10-6 g = 1 ug)
1. Obtain the mass of each element present (in grams)
2. Determine the number of moles of each type of atom present.
3. Divide the number of moles of each element by the smallest number of moles to convert the smallest number to 1. If all of the numbers obtained are integers (whole numbers), they are the subscripts in the empirical formula. If one or more of these numbers are not integers, go on to step 4.
4. Multiply the numbers you derived in step 3 by the smallest integer that will convert all of them to whole numbers. This set of whole numbers represents the subscripts in the empirical formula.
n = molar mass/empirical formula mass
71.65% Cl, 24.27% C, and 4.07% H
The molar mass is known to be 98.96 g. Determine the empirical formula and the molecular formula of this compound.
-A chemical reaction gives a visual sign.
1. Color change
2. Solid forms
3. Bubbles form
4. Heat and/or a flame is produced or heat is absorbed.
is read as “yields” or “produces”