1) Is the picture to the right a chemical reaction or a physical reaction? Why? 2) Is the following...
-
Upload
grace-harrison -
Category
Documents
-
view
213 -
download
0
Transcript of 1) Is the picture to the right a chemical reaction or a physical reaction? Why? 2) Is the following...
1) Is the picture to the right a chemical reaction or a physical reaction? Why?
2) Is the following equation balanced?CH4 + 2O2 CO2 + 2 H2O
3) Put the particles in order of slowest to fastest; gas, solid, liquid.
Welcome to class.Do Now
Flammable
C:1 H:4 O:4 C:1 H:4 O:4
Yes!
Solid, liquid, gas
2
Homework and Announcement Due: Conservation of Matter worksheet Word Find and Section Review
Achieve 3000 – Your choice, choose 2 due 20th
2
Chemical Reactions
• process of breaking of chemical bonds
• reforming of new bonds creates new substances.
• When you make pizza, which changes are physical and which are chemical changes?
Evidence of chemical changeFour indicators :
1. Formation of new gas
2. Formation of new solid
3. Release of energy (heat or light)
4. Color change
Reactants: Will be changed into new substance.
What you start with.Products: New Substance formed in chemical
reaction. What you end up with.
LETS REVIEW:
REACTANTS PRODUCTS
Reactants and products• In the reaction, methane (a natural gas) is
burned or combusted.
• Some energy is added to get the reaction started.
Conservation of Matter
CH4 + 2O2 CO2 + 2H2O
(1 C, 4H , 4 O) (1 C, 4 H, 4 O)
In a chemical reaction atoms are not created or destroyed, they are only rearranged.
Avogadro’s Number
6.02 x 1023 atoms or molecules.• The Avogadro number was named in
honor of Amedeo Avogadro who discovered that a mole of any gas under the same conditions has the same number of molecules.
• Johann Josef Loschmidt, a German physicist, named and discovered the Avogadro number. He realized that a mole of any substance—be it a gas, liquid, or solid—contains 6.02 x 1023 atoms or molecules.
What is the molar mass of one mole of CaCO3?
1. We Know
• chemical formula CaCO3
• # amu in formula = molar mass in grams
Solving Problems
• In this reaction, chalcocite (a mineral) reacts with oxygen in the presence of heat. The products are a type of copper oxide and sulfur dioxide. Balance this equation:
__Cu2S + __O2 → ___Cu2O + ___SO2
Balancing Equations Solving Problems
Think about it…
• Coefficients can be added in front of any chemical formula in a chemical equation.
• When a coefficient is added in front of a chemical formula, all atoms in that formula are multiplied by that number.
• Use common denominators to help choose coefficients to try.
Thermal Energy:
Movement of “Heat”; always flows warmer matter to cooler
matter.
Released or absorbed
Higher temperature = faster particles = more thermal energy
Which of the following has more thermal energy?
A melted chocolate bar.
A solid chocolate bar.
Why?
Higher temperature = higher thermal energy
Endothermic change:
Endo - In Thermos - heat
Heat is absorbed (heat is taken in)
Heat is a reactant.
Example:
Ice + Heat Water (Physical change)
Ca + Cu + Heat CaCu (Chemical change)
Which of these is endothermic?
Liquid water changes to Solid ice
Solid ice changes to Liquid water
Why?
Heat is absorbed so the particles move faster.
Exothermic change:
Exo - Out Thermos - Heat
Heat is released (heat exits)
Heat is a product.
Example:
2Mg + O2 Heat + Light + 2MgO (Chemical change)
Water Heat + Ice (Physical change)
Which of these is a exothermic change?
Instant cold packs
Instant hand warmer pack
Why?Because the hand warmer is releasing heat.
Pair Share
1. Photosynthesis. (CO2 + H2O + Energy O2 + Glucose)
Endothermic. Energy is a reactant. 2. Fireworks exploding? Exothermic. Energy is a product.
Powder + O2 Heat + Light + Gas 3. Baking a cake? Endothermic. Energy is a reactant. Batter + Heat Cake
Endothermic or Exothermic, Why?
Summary: 3-4 sentences about your notes.
1. What is molar mass? 2. What is the difference between
endothermic and exothermic reactions?
3. Give an example of an endothermic reaction.
4. Give an example of an exothermic reaction.