Answer:
ethanol is already at the ethanol's boiling point: (0.826 kJ/g) x (70.05 g) = 57.8613 kJ = 5.79 x 10^4 J.
Missing: 45.65 | Must include: 45.65
Explanation:
<span>A compound is found to be 40.0% carbon, 6.7% hydrogen and 53.5% oxygen. Its molecular mass is 60. g/mol.
</span>Q1)
Empirical formula is the simplest ratio of whole numbers of components making up a compound.
the percentages have been given, therefore we can calculate for 100 g of the compound.
C H O
Mass in 100 g 40.0 g 6.7 g 53.5 g
Molar mass 12 g/mol 1 g/mol 16 g/mol
Number of moles 40.0/12= 3.33 6.7/1 = 6.7 53.5/16 = 3.34
Divide by the least number of moles
3.33/3.33 = 1 6.7/3.33 = 2.01 3.34/3.33 = 1.00
after rounding off
C - 1
H - 2
O - 1
Empirical formula - CH₂O
Q2)
Molecular formula is the actual number of components making up the compound.
To find the number of empirical units we have to find the mass of one empirical unit.
Mass of one empirical unit = CH₂O - 12 + (1x2) + 16 = 30 g
Mass of one mole of compound = 60 g
Number of empirical units = 60 g / 30 g = 2
Therefore molecular formula - 2(CH₂O)
Molecular formula - C₂H₄O₂
In 1871, a Russian Chemist, Dimitri Mendeleev, gave a useful scheme for classification of elements. He presented the first regular periodic table in which elements of similar chemical properties were arranged in eight vertical columns called groups. The horizontal rows of table were called periods. He arranged elements in ascending order of their atomic masses and found that elements having similar chemical properties appeared at regular intervals. This observation was called Periodic Law.
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