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Accounting for the Law of Conservation of Matter/Mass
Accounting for the Law of Conservation of Matter/Mass
What evidence is present that indicates a chemical change is occurring?
How can we account for the changes in the mass of the steel wool?
How can we communicate these changes to others?
What are the reactants and products in the reaction?
Balancing Examples
Balancing Examples
On your whiteboard:
Write the chemical equation
Draw a model of each equation (using circles for atoms).
Create (reproduce the table) showing the number of each element within the UNBALANCED equation.
By adjusting the COEFFICIENTS on the molecules in the reaction, balance the equation.
Hydrochloric Acid and Ammonia
Hydrochloric Acid and Ammonia
Iron (III) and Oxygen
Iron (III) and Oxygen
Hydrochloric Acid and Magnesium
Hydrochloric Acid and Magnesium
How to write chemical equations…
How to write chemical equations…
Chemical equations are the way chemists describe chemical reactions.
It shows us the REACTANTS (starting materials) and the PRODUCTS of the reaction.
Reactants → Products
A WORD EQUATION will simply name the chemical reactants and products.
hydrogen gas + oxygen gas → water
A CHEMICAL EQUATION uses the chemical formulas instead of names. It often shows us the states of the substances in the reaction. A BALANCED CHEMICAL EQUATION also shows us how many molecules of each substance are involved in the reaction.
2 H2 (g) + 1 O2 (g) → 2 H2O (l)
Important Numbers:
Important Numbers:
SUBSCRIPTS: H2O - The subscript 2 after the Hydrogen shows that there are 2 Hydrogen atoms in a water molecule.
COEFFICIENTS: 3 FeO - The number in front of a chemical formula shows the number of molecules used or made. These numbers are called the COEFFICIENTS in a chemical equation. In this reaction there would be 3 molecules of Iron Oxide, or 3 Iron (Fe) atoms and 3 Oxygen (O) atoms.
We need to start by counting atoms!
Practice by building some molecules in the PhET sim below. Submit your screenshot of Multiple Molecules Collection TWO on GC. Your collection may be different than the collection in the assignment.
Give the number of atoms of each element in these examples (Highlight the text to reveal the answers):
a) H2O 2-H 1-O d) Al(OH)3 1-Al 3-O 3-H g) 4 MgCl2 4-Mg 8-Cl
b) CaCO3 1-Ca 1-C 3-O e) 3 FeO 3-Fe 3-O h) 2 Ca(OH)2 2-Ca 4-O 4-H
c) Mg(NO3)2 1-Mg 2-N 6-O f) 2 O2 4-O i) 3 Cu(NO3)2 3-Cu 6-N 18-O
Balancing Chemical Equations - Theory
Balancing Chemical Equations - Theory
Balancing Chemical Equations ChatBot
Please watch either (or both) of these videos as an introduction to the concept of balancing chemical equations.
Some check-in questions you should be able to answer following the unit:
Answer each question in 2-3 sentences.
What is a chemical equation and what information does it provide?
State the Law of Conservation of Mass.
Explain the significance of balancing chemical equations in relation to the Law of Conservation of Mass.
What are the steps involved in balancing a chemical equation?
Differentiate between subscripts and coefficients in a chemical equation.
Why can't subscripts be changed when balancing chemical equations?
What do the symbols (s), (l), (g), and (aq) represent in a chemical equation?
List three indications that a chemical reaction has occurred.
What is an exothermic reaction? Provide an example from the source material.
In the chemical equation 2H₂O₂(aq) → 2H₂O(l) + O₂(g), what do the coefficients '2', '2', and '1' (understood) signify?
Balancing Chemical Equations - Practice Examples
Balancing Chemical Equations - Practice Examples
Balancing Chemical Equations
Balancing Chemical Equations
Choose FOUR of the following to complete. You will then submit them to Google Classroom
- Opt 1 - Reactants, Products and Leftovers - PhET
Score at least 24 points in the GAME and submit a screen shot to GC.
Describe the process you would use to complete the following problem.
2. Opt 2 - Balancing Chemical Equations - PhET
2. Opt 2 - Balancing Chemical Equations - PhET
Score at least 24 points in the GAME and submit a screen shot to GC.
2. Explain how you would balance the equation above.
3. Opt 3 - Balancing Chem Rxns Practice
3. Opt 3 - Balancing Chem Rxns Practice
Work on the following problems. When you answer 5 (FIVE) in a row correctly submit a photo of your answers to GC.
NGSS9 - Balancing equations worksheet (2020 KEY).pdf
Complete 5 of the reactions on the SIMPOP site.
Add screen shots of your balanced equations to the Google Assignment.
Complete the five questions below the Gizmo, attach a screenshot of your score at or above 80%.
Click on image to access the GIZMO.
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