*

Balancing Chemical Equations using

PowerPoint Animation

Click here to see how to use this presentation

*You received a call today from a parts salesman in Walla Walla, Washington.

*He says that he heard you were one of the partners of a bicycle manufacturing plant in Jacksonville, Florida, and he had some parts to sell…cheap.

He said that he sold *bike frames and wheels in sets of two. *

The deal was awesome and would definitely help profits, but you, being the cautious business person that you are, decide to make a small order. That way you can build a small number to test to make sure that the parts are high quality.

You ask the salesman to hold* and you do some quick figuring…

If you buy* one set of tires *and one set of frames*, would you* have any left over *parts?*

You decide to draw it out on a sheet of paper*

You sketch out* a formula and take a look at it.* How many orders* should you buy* to make the least number of bikes* without any wasted parts?*

What do you think?

You see that you must buy* 1 order to get two frames, at a minimum, so you conclude that you must build at

least* two bikes.*

Now you have the right number of frames and the right number of bikes, but you only have two tires for two bikes.

You decide that you need two* orders of tires. *That will

give you enough tires for the bikes with no parts left over. *

*You take the salesman off hold and tell him your intentions.

“Great,” he says. “I’ll express mail the parts today, I’m confident that they will meet your needs.”

*

You call up your partner and tell her the news

“That’s nothing,” she says, “stop by my office and check out the deal I ran into. Is 2:30 OK?”

“Sure, see you then.”

*

*

The phone rings as soon as you hang up. It’s your friend with a unique problem…*

*

4 eggs 2 cups milk 1 stick butter 1 batch cookies

He says he’s baking cookies* and the recipe includes 4 eggs, 2 cups of milk, and 1 stick of butter.

He went to the store and found out that he couldn’t buy the items without getting confused. He called you because he says you’re good in math and he was hoping you could help solve the problem.

“So what’s the problem, ” you ask?

*

*

“I can only buy eggs in packages of 6, milk by the quart (which is 8 cups), and butter comes in boxes with 4 sticks. I have to buy these things so that there is nothing wasted. I can’t have anything left-over. How can I solve this?”

6 eggs 8 cups milk 4 sticks butter

*

*

4 eggs 2 cups milk 1 stick butter 1 batch cookies

6 eggs 8 cups milk 4 sticks butter*

You draw out the formula and take a look.*Here’s the recipe…

And here’s how you can purchase the items*

What do you think?

*

*

Here’s one way you can solve the problem…*

Let:

E represent Eggs

M represent Milk

B represent Butter*

So you buy 6 E + 8 M + 4B to get one batch of cookies or (4E2M1B)*

This can be shortened even more and still mean the same thing*

__E6 +__M8 +__B4 ___E4M2B1

*

__E6 +__M8 +__B4 ___E4M2B1*

*

On the left, we have the items in the quantities that they can be bought . The number of items is now shown as a subscript*

On the right, we have the items in the completed recipe. Since they mix together to form one batch, we don’t separate the items with plus signs. But we do show the quantity of each item with a subscript

*

__E6 +__M8 +__B4 ___E4M2B1

*

The first thing you should see is that you can only buy milk by the quart. This is eight cups of milk. And eight cups of milk makes four* batches of cookies, since each batch has 2 cups.

So first see if you can make 4 batches with one quart*

4

E4M2B1

E4M2B1**

E4M2B1

+E16M8B4

1

__E6 +__M8 +__B4 ___E4M2B1*

*

4

E4M2B1

E4M2B1

E4M2B1

+E16M8B4

The milk and butter look like they would work but the eggs won’t.*

We can only buy them 6* at a time and 6* won’t go into 16. We’ll have to buy another quart of milk

1

__E6 +__M8 +__B4 ___E4M2B1

*

8

E4M2B1

E4M2B1

E4M2B1

+

With 2 quarts of milk, the milk and butter look like they will work out because you could buy 2 boxes of butter, but the eggs still won’t work because 6 won’t go into 32.*

2

E4M2B1

E4M2B1

E4M2B1

E4M2B1

E32M16B8

E4M2B1

2

What do you thinkwill happen if you buy 3 quarts of milk?

__E6 +__M8 +__B4 ___E4M2B1

*

12

Yes, the problem is solved by purchasing 3 quarts of milk, 3 boxes of butter, and 8 cartons of eggs

You must bake a minimum of 12 batches of cookies

3 38

__E6 +__M8 +__B4 ___E4M2B1

*

12

When you place a numbers in front to increase the number of each item, we call this number the…*

3 38

Coefficient*

__E6 +__M8 +__B4 ___E4M2B1*

*

12

What’s an easy way to compare the number of eggs, cups of milk, and sticks of butter, on each side of the equation?

3 38

__E6 +__M8 +__B4 ___E4M2B1

*

123 38

Correct. When you multiply the coefficient by the subscript, you get the total*

Now let’s try one more. It’s time for your 2:30 appointment with your partner. This deal is a little more complicated. She says that the supplier sells parts as follows:

Handlebars: 3 to an order

Frames: 5 to an order

Wheels 4 to an order

OR

___W4 + ___F5 + ___H3 → ___W2F1H1

W-Wheel + F-Frame + H-Handlebart WFH

What do you think the answer is?

___W4 + ___F5 + ___H3 → ___W2F1H115 6 10 30

If your calculations are correct, you should have gotten the answer above*

*

What you have been doing is actually no different than balancing chemical equations. In fact, the first problem is no different than balancing oxygen with hydrogen to form water. Instead of wheels and frames to make a bike, you have 2 hydrogen atoms and two oxygen atoms to form water.

HH

HH

HH

HHOO

OOOO

__H2 + __O2 __H2O*

HH

HH

HH

HHOO

OOOO

__H2 + __O2 __H2O*

Now we are going to animate the balancing of a chemical equation using the PowerPoint Program *

HH

HH

HH

HHOO

OOOO

__H2 + __O2 __H2O

*

First we see that the hydrogen is balanced, but there are two oxygen on the left side and one on the right side, so we double the water molecule on the right by adding a coefficient of two.

2

HH

HHOO

**

HH

HH

HH

HHOO

OOOO

__H2 + __O2 __H2O

*

Next you double the hydrogen on the right to get four.

2

HH

HHOO

2

HH

HH

* *

HH

HH

HH

HHOO

OOOO

__H2 + __O2 __H2O

*

Now you can show that the equation is balanced by removing the molecules on the right side and rearranging the molecules on the left into the molecules on the right.

2

HH

HHOO

2

HH

HH

* * * *

HH

HH

HH

HHOO

OOOO

__H2 + __O2 __H2O

*

Another way to show that the sides balance is to stack the atoms and compare.

2

HH

HHOO

2

HH

HH

* * * *

How to make a formula with subscripts

How to make atoms and molecules

How to animate text and objects

Another example of a more difficult equation