Atoms and Mass are conserved
during a chemical reaction
SNC 2D
Balanced chemical Equation
The number of atoms as reactants must equal the
number of atoms of the products.
REACTANTS
PRODUCTS
2 atoms of Sodium React to produce 2 molecules of Sodium
Hydroxide and 1
React with
molecule of Hydrogen
2 molecules of water
gas.
Conservation of Mass
• During a chemical reaction, atoms are not
created or destroyed. The atoms in the
reactants are rearranged to form the new
product substances.
• This fact is summarized in a scientific law
called the “Conservation of Mass”.
How can this be proved?
• Experimental evidence can be measured to
show that the mass of the reactants is the
same as the mass of the products.
2AgNO3 + Cu
Cu (NO3)2 + 2Ag
Mini Investigation
Copper(II)Chloride + Aluminum
3Cu Cl2 +
2Al
What did you observe?
Aluminum Chloride + Copper
2Al Cl3 +
3Cu
•
•
•
•
Colour change?
Change in temperature?
Bubbles of gas?
New substance(s)?
What type of reaction?
A.
B.
C.
D.
Synthesis
Single displacement
Double displacement
Combustion
Answer: Single Displacement.
Reactivity of metals
• Metals will react/displace other metals in a
certain order.
• This is called the reactivity series.
Mnemonic
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zebra into tender loving care. single girls
please.
Can Metals be Active?
• Metals lose electrons to become CATIONS.
Metals that lose electrons more easily will
displace metals that hold on to their electrons.
• The ease with which the metal loses its
electrons determines its place in the reactivity
series.
• Metals that lose only one electron to achieve
the stable octet tend to be more reactive.
• Potassium which loses the one electron in its
valence shell to form a stable octet. Because
this lone electron is further from the nucleus
than the lone electron in sodium or lithium it
is not held in place by the positive attractive
forces of the nucleus. Remember that
opposite charges attract.
• Precious metals such as gold silver and
platinum cannot easily lose the required
electrons to form the stable octet. Therefore
they are less reactive than potassium.
Potassium Atom
Aluminum Atom
Lab Investigation
• Purpose:
To prove the law of Conservation of Mass.
In this lab you will carry out the following skills:
1. Perform and record - carry out experiment
2. Analyze and interpret – make a data table
and record observations.
3. Communicate – write up a formal lab report
Formal Lab
• Must follow the correct format.
• Procedure Must be written in past tense
passive tense.
• NO pronouns are allowed at all in a lab report.