Balancing Equations - WordPress.com
Transcript of Balancing Equations - WordPress.com
Let’s bake a cake • What ingredients do you need? Be as specific as possible
1 (18.25-ounce) box white cake mix) 1 large orange, zested, about 1/4 cup 1 1/3 cups no pulp orange juice 3 egg whites 2 tablespoons vegetable oil Frosting: 1/2 stick (4 tablespoons) unsalted butter, at room temperature 1/3 cup creme fraiche 1 pound powdered sugar 1/4 cup raspberry jam Water, as needed 1/4 cup raspberry jam 1 (6-ounce) container fresh raspberries
Cake3 tablespoons unsalted butter, melted and cooled, plus more for buttering cake pan 1/2 cup (2 1/2 ounces) unbleached all-purpose flour plus more for dusting cake pan 1/4 cup Dutch-process cocoa 6 large eggs, at room temperature 3/4 cup (4 3/4 ounces) superfine sugar 1 teaspoon vanilla extract Syrup1/2 cup sugar, 1 ounce (2 tablespoons) kirsch Assembly4 cups heavy cream 1 cup (4 ounces) powdered sugar 2 teaspoons vanilla extract 2 cups Spirited Sour Cherries , 8 fresh cherries with stems (optional) About 2 1/2 ounces dark chocolate (at least 60% cacao) in a single block About 1/2 cup ground dark chocolate (at least 60% cacao) or chocolate cookie crumbs Powdered sugar for dusting
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Starter
• Which of these substances are elements?
• What are the others called?
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Aim
• Balance chemical symbol equations
Key words
• Compounds
• Chemical formula
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Have you ever wondered?
The bigger picture
How do chemists know how to combine chemicals in the right way?
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100g g melting
100
Let’s start by looking at food to learn how to write chemical formulae
• It has changed state from solid to liquid. • No chemical reaction has taken place.
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100g + 50g g 150
Let’s add Smarties to the chocolate mix
• A new product (smocolate) has been formed. • A chemical reaction has taken place.
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100g + 50g g 150
Let’s add Smarties to the chocolate mix
• Mass reactants = mass products • The law of conservation of mass 17/05/2016 ©cgrahamphysics.com 2016
200g + g 300 g 100
• Write a word equation for the production of smocolate: • Chocolate + Smarties Smocolate
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Lets make up some formulae
Chocolate = Ch
Smarties = Sm
Smocolate =
What is the chemical formula for Smocolate?
ChSm 2
Each chunk of Smocolate has two Smarties on top, correct the formula.
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ChSm2
ChSm2
The small number means there are 2 Smarties in the Smocolate molecule.
2
The big number means there are 2 Smocolate molecules
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Ch + Sm ChSm2
Balance this equation so the REACTANTS add up to make the PRODUCT.
2
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Now try these!
1. 2Ch + __Sm __ ChSm2
2. __Ch + 6Sm __ ChSm2
3. __Ch + __Sm 4ChSm2
4. 5Ch + __Sm __ ChSm2
4 2
3 3
4 8
10 5
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Oh no! We can’t get normal Smarties any more. Only Supersmarties that
come in threes!
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Spersmarties 𝑆𝑚3
Supersmarties
can be broken
apart to make
Smocolate, but we
can only buy them
stuck together.
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Try making Smocolate with Supersmarties!
__Ch + 2Sm3 __ ChSm2
3 3
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Now apply that to atoms.
carbon + oxygen carbon dioxide
C + O2 CO2
Does this equation balance?
Yes, there are the same number of each atom in the reactants and
products. 17/05/2016 ©cgrahamphysics.com 2016
Now apply that to atoms.
hydrogen + oxygen water
H2 + O2 H2O
Does this equation balance?
No, there is more oxygen in the reactants than the products.
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hydrogen + oxygen carbon dioxide
__H2 + __O2 __H2O
Balance the equation
2 2
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Plenary: MWB
• Draw an element
• Draw a mixture
• Draw a compound
• Draw a molecule
• List the diatomic molecules
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Balance the equations
• 𝐶3𝐻8 + 𝑂2 𝐶𝑂2 + 𝐻2𝑂
• 𝐶4𝐻10 + 𝑂2 C + 𝐻2𝑂
• 𝐶4𝐻10 + 𝑂2 CO + 𝐻2𝑂
• 𝐶4𝐻10 + 𝑂2 𝐶𝑂2 + 𝐻2𝑂
• 𝐶5𝐻12 + 𝑂2 𝐶𝑂2 + 𝐻2𝑂
• 𝐶6𝐻14 + 𝑂2 CO + 𝐻2𝑂
5 3 4
2 5 8 10
2 9 8 10
2 13 8 10
8 5 6
2 13 12 14
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