Oct 20, 2015
Law of Mass Conservation
Law of Definite (or Constant)
Composition
Gay-Lussac’s Law of
Combining Volumes
The Law of Multiple
Proportions
THE FUNDAMENTAL LAWS OF CHEMISTRY
Law of Mass Conservation
Antoine Laurent Lavoisier Paris, 28th of August 1743 to 8th
of May 1794
Zn(s) + S(s) → ZnS(s)
65.4 g 32 g 97.4 g
Law of Definite (or Constant)
Composition
Joseph Proust Born: Angers (France), 1754 Died: Angers (France), 1826
• Father was a pharmacist.Father was a pharmacist.
• He taught Chemistry in Spain.He taught Chemistry in Spain.
• Napoleon destroyed Proust’s Napoleon destroyed Proust’s labs while invading Spain in labs while invading Spain in 1807.1807.
Joseph Proust – 100 lbs of copper combined with acid and carbonates always yielded 180 pounds of green carbonate.
In 1799 he proposed the A chemical compound, no matter what its origin or its method of preparation, always has the same composition; i.e., the same proportions by mass of constituent elements.
Law of Multiple Proportions:– Elements may combine in
more than one set of proportions, with each set corresponding to a different compound.
– CO2: always 3 g C and 8 g O
– CO: always 3 g C and 4 g O
The Law of Multiple
Proportions
John Dalton Eaglesfield, North UK,
1766-1844
If two elements form more than a single compound, the masses of one element combined with a fixed mass of the second are in the ratio of small whole numbers.
Joseph Louis Gay-Lussac (1778-1850)
Gay-Lussac’s Law of
Combining Volumes
The volumes ratio of the gases involved in a
chemical reaction (both reactants and products) is
the simple integer.
When two gases are allowed to react, such that the gases
are at the same temperature and pressure,
the volumes of each gas consumed will be in the ratio of small integers.
FOUR LAWS • Law of Mass Conservation: The total mass of material
present after a chemical reaction is the same as before the reaction (Lavoisier).
• Law of Definite (or Constant) Composition: No matter what its source, a particular chemical compound is composed of the same elements in the same parts (fractions) by mass (Proust).
• The Law of Multiple Proportions: When two elements form a series of compounds, the masses of one element that combine with a fixed mass of the other element are in the ratio of small integers to each other (Dalton).
• Gay – Lussac’s Law of Combining Volumes: The volumes of two reacting gases (at the same temperature and pressure) are in the ratio of simple integers. Moreover, the ratio of the volume of each product gas to the volume of either reacting gas is the ratio of simple integers.
CONSERVATION OF MASS• Matter is neither created nor destroyed in a
chemical reaction. • In every chemical operation an equal
quantity of matter exists before and after the operation.
• Mass is conserved in a chemical reaction.• Moreover, in chemical change, the mass of
the elements is conserved, element by element.
• Development of this law was made possible by the analytical balance.
The mass of substances before and after chemical reaction is equal
QUESTION In closed tube, 32 grams of sulfur reacts with 63.5 grams of copper produce copper(II) sulfide. How many grams of copper(II) sulfide are formed as a product?
SOLUTIONsulfur + copper copper(II) sulfide32 g 63.5 g 95.5 g
CONSERVATION OF MASS
The ratio of elements mass in a compound is constant
DEFINITE PROPORTIONS
Salt (g)
Sodium (g)
Chlor (g)
MaduraCirebon
0.2925 1.7750
0.1150 0.6900
0.1775 1.0650
QUESTIONThe result of salt research from Madura and Cirebon yields the following data:
Prove that salt has constant ratio of element!
Madura’s salt : % sodium = 2925.0
1150.0 x 100% = 39.3%
Madura’s salt : % chlor = 2925.0
1775.0 x 100% = 60.7%
Cirebon’s salt : % sodium = 7750.1
690.0 x 100% = 39.3%
Madura’s salt : % chlor = 7750.1
0650.1 x 100% = 60.7%
This is proven that the ratio of sodium and chlor in both salts are constant,
although their origin are different.
SOLUTION
MULTIPLE PROPOTIONWhen two elements form a series of compounds, the masses of one that combine with a fixed mass of the other are in the ratio of small integers to each other
QUESTIONNitrogen can form many compounds with oxygen. The data from the experiment as follow:
Compounds of Nitrogen and Oxygen1 2 3 4 5
Nitrogen 14 g 14 g 28 g 28 g 28 gOxygen 16 g 32 g 16 g 32 g 80 g
Does the result of experiment agree with law of multiple proportion?
MULTIPLE PROPOTION
COMBINING VOLUMESQUESTION1 volumes of nitrogen + 1 volume of
oxygen → 2 volumes of nitrogen oxide.
In chemical equation :N2 (g) + O2 (g) 2 NO (g)
Soal untuk didiskusikan1. Kalsium karbonat (10,00g) direaksikan dengan 100,0cm3 asam klorida (ρ=1,148g/cm3). Hasilnya adalah 120,4g larutan (campuran HCl dan CaCl2) dan 2,220L gas karbon dioksida (ρ=1,976g/L). Tunjukkan apakah hasil tersebut sesuai dengan Hukum Kekekalan Massa.2. Sebanyak 8,04g tembaga oksida direduksi dengan hidrogen menghasilkan 6,24g tembaga. Pada eksperimen kedua, 9,48g tembaga dilarutkan dalam asam nitrat pekat. Setelah larutan ini diuapkan sampai kering dan residu dipijar sampai
konstan, diperoleh 11,88 gr tembaga oksida. Tunjukkan bahwa kedua data di atas mengikuti hukum kimia4. Merkuri dan klor membentuk dua macam senyawa. Dalam satu senyawa 0,66g merkuri bergabung dengan 0,118g klor. Dalam senyawa yang lain 1,00g merkuri bergabung dengan 0,355g klor. Tunjukkan bahwa data ini sesuai dengan Hukum Kelipatan Perbandingan.