hw 8d (2) - combustion reactions worksheet, with key (11-12)

HW 8D(2) - HR / Name Combustion Reactions Worksheet When a fuel (those that contain hydrogen and carbon) burns completely, it reacts with oxygen (02) to produce carbon dioxide (C02) and water vapor (H20). In this activity, you will write and balance chemical equations for combustion reactions. The steps are listed below: 1. Write the general form of the equation. For methane (CH4), the equation would be: 2. The number of atoms of each element on the left side of the equation must equal the number of atoms of each element on the right side of the equation. To "balance" the equation, we use coefficients, which are placed in front of each reactant or product. TIP COMBUSTION: 1. Bajance the carbon and hydrogen atoms first. 2. Count the product oxygen atoms; decide what you need to do based upon whether there are an odd (double) or even number of product oxygen atoms. 3. If the compound being burned contains oxygen, deduct that same number of oxygen atoms from the product oxygen count. Example: 1. Carbons are already balanced (1 on each side), There are 4 hydrogen atoms on the left and 2 on the right. Put a coefficient of 2 in front of the H20. 2. Count the number of product oxygen atoms. Here there are 4 atoms of oxygen on the product side of the equation, an even number. Place a coefficient of 2 in front of the O2 on the reactant side of the equation. 2 oxygen + 2 oxygen = 4 total oxygen CH4 + - 2 02 + C02 + - 2 H20 Now the equation is balanced! 3. If you end up with an odd number of oxygen atoms on product side of the equation, use that number as the coefficient for the 0 2 , and then double all of the other coefficients.

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Chemistry Balancing Equations

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HW 8D(2) - HR / Name

Combustion Reactions Worksheet

When a fuel (those that contain hydrogen and carbon) burns completely, it reacts with oxygen (02) to produce carbon dioxide (C02) and water vapor (H20). In this activity, you will write and balance chemical equations for combustion reactions. The steps are listed below:

1. Write the general form of the equation. For methane (CH4), the equation would be:

2. The number of atoms of each element on the left side of the equation must equal the number of atoms of each element on the right side of the equation. To "balance" the equation, we use coefficients, which are placed in front of each reactant or product.

TIP COMBUSTION: 1. Bajance the carbon and hydrogen atoms first. 2. Count the product oxygen atoms; decide what you need to do based upon whether there

are an odd (double) or even number of product oxygen atoms. 3. If the compound being burned contains oxygen, deduct that same number of oxygen

atoms from the product oxygen count.

Example:

1. Carbons are already balanced (1 on each side), There are 4 hydrogen atoms on the left and 2 on the right. Put a coefficient of 2 in front of the H20.

2. Count the number of product oxygen atoms. Here there are 4 atoms of oxygen on the product side of the equation, an even number. Place a coefficient of 2 in front of the O2 on the reactant side of the equation.

2 oxygen + 2 oxygen = 4 total oxygen CH4 + - 2 0 2 + C02 + - 2 H20

Now the equation is balanced!

3. If you end up with an odd number of oxygen atoms on product side of the equation, use that number as the coefficient for the 02 , and then double all of the other coefficients.