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.