Download 3/14/12 - Bellringer - Trimble County Schools

3/15/12 - Bellringer
• What kind of reactions can you think of?
(Think outside the box!)
• Turn in 4 bellringers from this week when
finished.
Objectives
• 1. Identify the reactants and products in a
chemical reaction.
• 2. Determine how a chemical reaction
satisfies the law of the conservation of
matter.
• 3. Determine how chemists express
chemical changes using equations
Chapter 23 – Chemical
Reactions
23.1 – Chemical Changes
Chemical Reactions
• Chemical reaction – a change in which one
or more substances are converted to new
substances
• Reactants – the substances that react
• Products – the new substances produced
Different Reactions
• Chemical reactions – use the ELECTRONS
to form new substances
• Nuclear reactions - use the NUCLEUS to
form new substances
• What does a chemical reaction look like?
Chemistry Kitchen
Chemistry Kitchen
REACTANTS
PRODUCTS
Think about it…
• If you burned a piece of paper, you end up
with a pile of ashes.
• Once burned, is there…
– More mass?
– Same mass?
– Less mass?
• Why?
Conservation of Mass
• Conservation of Mass - a Law that
states in a chemical reaction,
matter is not created or destroyed
– Antoine Lavoisier experimented
with mercury (II) oxide and heat
– He found mass of products (liquid
mercury and oxygen gas) equaled
mass of reactants
3/19/12 - Bellringer
• Boiling or freezing water is NOT a
chemical reaction. Why?
• Turn in 4 bellringers from last week if
absent Thursday.
Chemical Equation
• Uses chemical formulas and symbols to
describe a chemical reaction and the
product(s) it produces
– Chemical formula expresses the relationship
between elements in the compound and
molecules they
make up
Coefficients
• Numbers which represent the number of
units of each substance in a reaction
– Knowing coefficients of chemical reactions
allows chemists to use the correct amount of
reactants to predict the amount of products (law
of conservation applies)
Example
Subscripts and Symbols
• Numbers which represent the number of atoms in
a molecule of a particular element
• Symbols used to show state of reactants
– (s) solids
– (aq) aqueous
– (l) liquid
– (g) gas
Volcano with a Twist
• Reactants?
• Products?
• Equation:
• NaHCO3 + CH3COOH => CH3COO-Na+ +
H2O + CO2
• States?
• Conservation?
Notes Supplement
• Chemical equations will look similar to…
#AB(state) + # CD(state) → #AC(state) + #BD(state)
Reactants (left) → Products (right)
Arrow means “yields”
Practice
• SnO2(s) + 2 H2(g) → Sn(s) + 2 H2O(g)
• CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)
In class assignment / homework:
• Section 1 Reinforcement
• Balancing Chemical Equations PART A
AND B ONLY
Closure Question
• SnO2(s) + 2 H2(g) → Sn(s) + 2 H2O(g)
•
•
•
•
What are the reactants?
What are the products?
How is matter conserved / equalled out?
What changed? (Compounds and States)