Chemistry Unit 7 Lesson 1: Chemical Equations

Chemistry Unit 7 Lesson 1: Chemical Equations

By Ryan McCluskey

Our goal today is to learn the parts of chemical equations to begin our understanding of balancing chemical equations.

Chemical Equations

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A chemical equation is a shorthand way of writing out what is happening during a chemical reaction.

The ​goal is to organize all the important parts into something that resembles a math equation.

Chemical Equations

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In a chemical equation the left side of the equation is referred to as the reactant side. This is what you started with or what existed before the reaction occurred.

Chemical Equations

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In a chemical equation the right side of the equation is referred to as the product side. This is what you finish with or what is created by the reaction.

Chemical Equations

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A  +  B ----> C + D

Reactants   Products

Chemical Equations

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A  +  B ----> C + D

Reactants   Products

The reaction is always split by the Yields sign.

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Chemical Equations

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Chemical Equations

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​Photosynthesis is an example of a chemical reaction. This equation demonstrates how plants will use the reactants carbon dioxide and water to produce the products glucose (sugar) and oxygen.

Chemical Equations

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You might also remember that Animals simply flip the process. We eat these sugars and breathe in oxygen using them as Reactants to produce energy and breathe out Products such as carbon dioxide and water.

Chemical Equations

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C₆H₁₂O₆ + 6O₂ 🡪 6CO₂ + 6H₂O

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We can use this equation to look at two other important pieces of equations. ​

Chemical Equations

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C₆H₁₂O₆ + 6O₂ 🡪 6CO₂ + 6H₂O

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The first are Subscripts. ​Subscripts only describe the element that appears directly before them.

Chemical Equations

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C₆H₁₂O₆ + 6O₂ 🡪 6CO₂ + 6H₂O

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The second are Coefficients. ​Coefficients are used to describe having multiple of a whole molecule. They multiply all elements in the compound.

Fill in the Blank

C₆H₁₂O₆ + 6O₂ 🡪 6CO₂ + 6H₂O

How many Carbon atoms are in the Reactant side of this equation?

Fill in the Blank

C₆H₁₂O₆ + 6O₂ 🡪 6CO₂ + 6H₂O

How many Carbon atoms are in the Product side of this equation?

Fill in the Blank

C₆H₁₂O₆ + 6O₂ 🡪 6CO₂ + 6H₂O

How many Hydrogen atoms are in the Product side of this equation?

Chemical Equations

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C₆H₁₂O₆ + 6O₂ 🡪 6CO₂ + 6H₂O

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Some students like to think of Coefficients like disribution in ​math class.

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Fill in the Blank

3Pb₃(PO₄)₄

Using your knowledge of subscripts and coefficients how many Phosphorous atoms are present in these 3 molecules of lead (IV) phosphate?

Fill in the Blank

3Pb₃(PO₄)₄

Using your knowledge of subscripts and coefficients how many Oxygen atoms are present in these 3 molecules of lead (IV) phosphate?

Chemical Equations

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C₆H₁₂O_6(s) + 6O_2(g) 🡪 6CO_2(g) + 6H₂O_(g)

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Another piece of information that is commonly included in a chemical equation is the state of matter for each piece. ​

Chemical Equations

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C₆H₁₂O_6(s) + 6O_2(g) 🡪 6CO_2(g) + 6H₂O_(g)

​These are abbreviated to save space​.

(s) = solid

(g) = gas

(l) = liquid​

(aq) = ...?​

Open Ended

What do you think aq might stand for? It is a very common form of matter in everyday chemistry.

Chemical Equations

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C₆H₁₂O_6(s) + 6O_2(g) 🡪 6CO_2(g) + 6H₂O_(g)

​These are abbreviated to save space​.

(s) = solid

(g) = gas

(l) = liquid​

(aq) = aqueous - simply means dissolved in water

Words to Equations

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​Sodium carbonate solid decomposes to yield a solid sodium oxide powder and the release of carbon dioxide gas.

Words to Equations

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​Sodium carbonate solid decomposes to yield a solid sodium oxide powder and the release of carbon dioxide gas.

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​Na₂CO_3(s) 🡪 Na₂O_(s) + CO_2(g)

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Words to Equations

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Aluminum metal reacts with aqueous copper II chloride to produce aqueous aluminum chloride and solid copper precipitate.

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Words to Equations

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Aluminum metal reacts with aqueous copper II chloride to produce aqueous aluminum chloride and solid copper precipitate.

Al_(s) + CuCl_2(aq) 🡪 AlCl_3(aq) + Cu_(s)

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