If the empirical formula of a compound is CH2O and its molecular weight is 180 g/mol,
what is its molecular formula?
Empirical Formula = CH2O
Empirical formula mass = 12 + 2*1 + 16 = 30
Molecular weight = 180 g/mole
Therefore,
n = Molecular weight / Empirical formula mass = 180/30 = 6
Thus,
Molecular formula = (Empirical Formula)n = (CH2O)6 = C6H12O6
What is the empirical formula of a compound that is 43% carbon and 57% oxygen?
Relative number of atoms of C = 43 / 12 =3.58
Relative number of atoms of O = 57 / 16 = 3.56
The ratio is 1 : 1 and the formula is CO
What is the molar mass of iron(III) fluoride?
The molar mass of iron(III) fluoride (FeF3) = 55.847 + 3*10.998 = 88.841
What is the percent of oxygen in manganese(II) nitrate?
The molar mass of Mn(NO3)2 = 54.9 + 2*14.0 + 6*16.0 = 178.938 g
The mass of oxygen in 1 mole of Mn(NO3)2 = 6*16.0 = 96 g
Thus the percent of oxygen in manganese(II) nitrate is
% O = (96 /178.9)* 100% = 53.66%
What is the percentage composition of CO?
Molecular mass of CO = 12 + 16 = 28
The percentage of C = (12/28)*100 = 42.86
The percentage of O = (16/28)*100 = 57.14
A molecular compound has the empirical formula XY3. Which of the following is a
possible molecular formula?
The molecular formula will be of the form (XY3)n, where n = 1,2,3…
If n =2, then (XY3)2 = X2Y6
What is the molecular formula of a compound that has a formula mass of 50.48 amu and
an empirical formula of CH3Cl?
Empirical Formula = CH3Cl
Empirical formula mass = 12 + 3*1 + 35.453 = 50.453
Molecular weight = 50.48
Therefore,
n = Molecular weight / Empirical formula mass = 50.48 /50.453 = 1 (approximately)
Thus,
Molecular formula = (Empirical Formula)n = (CH3Cl)1 = CH3Cl
The whole number in front of a symbol or formula is called the
Coefficient
What is (g) a symbol for?
Gas
What does (aq) mean?
in water solution (aq stands for aqueous meaning water)
What is the balanced form of the equation: Hg + O2 -> HgO ?
2Hg + O2 -> 2HgO
What is the word equation for : Ca + Br2 -> Ca Br2?
Calcium + Bromine -> Calcium bromide
What law must be satisfied in writing a balanced chemical equation?
Law of Conservation of Mass
What is the balanced equation for the following: sodium + oxygen -> sodium oxide ?
4Na + O2 -> 2Na2O
What is the balanced form of the following equation?
lithium + magnesium chloride -> lithium chloride + magnesium
2Li + MgCl2 -> 2LiCl + Mg
Which observation does not indicate that a chemical reaction has occurred?
Change in total mass of substances
After the first steps in writing an equation, the equation is balanced by
Adjusting coefficients to the smallest whole-number ratio