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Laws of Matter

Here are the key steps: - In the first compound, 1g of A combines with 1.44g of B - In the second compound, 0.15g of A combines with 0.65g of B - Take the ratio of amounts of B that combine with the fixed amount of A (1g in the first compound) - Ratio of B in the first compound to B in the second compound is: 1.44g/0.65g = 2.2 - 2.2 is a ratio of small whole numbers, satisfying the law of multiple proportions. Therefore, the given data illustrates the law of multiple proportions since the masses of element B that combine with a fixed mass of element

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Mark Cuarez
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202 views16 pages

Laws of Matter

Here are the key steps: - In the first compound, 1g of A combines with 1.44g of B - In the second compound, 0.15g of A combines with 0.65g of B - Take the ratio of amounts of B that combine with the fixed amount of A (1g in the first compound) - Ratio of B in the first compound to B in the second compound is: 1.44g/0.65g = 2.2 - 2.2 is a ratio of small whole numbers, satisfying the law of multiple proportions. Therefore, the given data illustrates the law of multiple proportions since the masses of element B that combine with a fixed mass of element

Uploaded by

Mark Cuarez
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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ATOMS, IONS AND

MOLECULES
• Laws of Matter
Dalton’s Atomic Theory
OBJECTIVES:

• Explain how the basic laws of matter led to


the formulation of Dalton’s Atomic Theory

• Describe Dalton’s Atomic Theory


Table 4. Activity Data Sheet on Law of Conservation of Mass

Mass of Flask (g)

Open Closed

After adding vinegar

Baking soda packet

Flask (with cork) and


packet

After inserting the packet

Mass difference after


reaction

NaHCO3(s) + HC2H3O2(aq) CO2(g) + Na+(aq) + C2H3O2-(aq)


1. Law of Conservation of Mass : Antoine Lavoisier

Mass is neither created nor destroyed in


chemical reactions.
• The mass of the substances before a
chemical change/reaction is the same as the
mass of the substances produced by the
chemical change.

• The mass of the substances before and the


mass of the substances after the reaction are
equal.
Sample Exercises:
• If 46.5 grams of reactants are used in the following
reaction, what will be the mass of the products?

Zn (s) + 2 HCl (aq) --- > ZnCl2 (aq) + H2 (g)

• Consider the following reaction,

Ca (s) + ZnCO3(aq) --- > CaCO3 (aq) + Zn (g)


50 g 150 g 125 g ?
what mass of zinc in grams is produced?
Seatwork

Sodium chloride can be formed by the


reaction of sodium metal with chlorine gas. If
45.98 g of sodium combine with an excess of
chlorine to form 116.89 g of sodium chloride,
how much chlorine gas is used in the reaction?
2. Law of Definite Composition : Joseph Proust
Any sample of a compound will invariably
have the same proportion by mass of its
constituent elements.
• water

• carbon dioxide

• methane
Sample Exercises:
• A pure sample of sodium fluoride (NaF) contains 35 g of
sodium. How many grams of fluorine are present in this
sample?

• If 40% of a 300 g NaCl solution is sodium, what is the mass


of the sodium present in the sample?

• If there are 42 g of hydrogen in a sample of pure methane


(CH4), how many grams of carbon are present?
Seatwork:

• If there are 19 g oxygen in a sample of aluminum


oxide, (Al2O3), how many grams of aluminum are
present?
3. Law of Multiple Proportion : John Dalton
Elements can combine in different ways to form
different substances, whose mass ratios are small
whole numbers.

When two elements A and B form two different


compounds, the masses of element B that
combine with a fixed mass of element A can be
expressed as a ratio of small whole numbers.
Take nitrogen monoxide (NO) and nitrogen dioxide (NO2) as example

NO NO2
Two elements A and B form two
different compound. In the first
compound one gram of A is
combines with 1.44g of B. In the
second compound 0.15g of A is
combined with 0.65g of B. Show
how these data illustrate the law of
multiple proportions.

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