3/15/12 - bellringer what kind of reactions can you think of? (think outside the box!) turn in 4...
TRANSCRIPT
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)