Module 8 Labs

Learning Outcome

Students will successfully convert between units of mass and mole, and assess the relationships between reactants and products through calculation and experimentation.

Lab 1

Lab 1 Instructions

Part 1

In this example, lima, black, pinto beans, and lentils will be used. See the materials list for alternatives if beans are not available to you.

Refer back to your notes and review the concept of the mole.

In this lab exercise, 25 lentils will become the mole, and you will calculate the relative mass of each of the other beans.

Step One:

You will figure out how much 25 lentils weigh. This will become the mole.

Using a kitchen scale, place a cup on the scale and hit the TARE button. Then, place 25 lentils in your cup and record the number of grams the scale reads. If your scale does not have the ability to TARE, then you can measure the cup alone and subtract the weight of the cup from the lentils. Record the weight of the 25 lentils. The weight of the 25 lentils will become the relative mass to which all the other beans are compared.

Step Two:

Using the same scale and cup, measure the weight of 25 lima beans. Remember to deduct the weight of the cup. Record in your notes how many grams 25 lima beans weigh.

Step Three:

Repeat Step Two with the black beans and the pinto beans. Record each of their weights separately in your notes.

Step Four:

Use the table below to enter the calculations you recorded for each type of bean. Don't worry about the relative mass column until Step Five.

Type of Bean	Weight (g)	Relative Mass
lentils		1
lima beans
black beans
pinto beans

Step Five:

If the lentils = relative mass of 1, then all the other beans must be compared to the weight of the lentils. In order to figure out the relative mass, you must calculate by dividing the weight of each other type of bean by the weight of the lentils.

If the lentils were to weigh 1.5 grams and the lima beans 7 grams, then you would divide 7 by 1.5 and 4.66 grams would be the relative mass of the lima beans to the lentils.

Using your calculations, complete the table above.

Step Six:

How many of each bean equals the relative mass?

Using the table above, add each type of bean to the scale to see how many beans it takes to reach the relative mass you calculated for that bean above.

For example: If 4.66 grams is the relative mass of lima beans to lentils, how many limas equal 4.66 grams? Use the scale and trial and error to figure it out.

Record in your notes: Do you hypothesize the number of beans for each relative mass to be the same, similar, or completely different?

Use the table below to help you record your answers.

Type of Bean	Relative Mass	How Many Beans?
lentils	1	25
lima beans
black beans
pinto beans

What do you conclude about these numbers? Was your observation consistent with your hypothesis? Why or why not?

Step Seven:

Try using the same process with unpopped popcorn kernels and popped popcorn.

What is the relative mass of the popped popcorn to the kernels? How much popped popcorn equals the mass of the unpopped kernel?

Lab 2

Lab 2 Instructions

Part 2

Use the recipe below to help you experiment with the following research.

Ingredient List

3 and 1/4 cups (420g) bread flour
2 teaspoons coarse salt
1 and 1/2 cups (360ml) cool water

If the bread recipe claims to yield 10 servings, calculate the relative mass of each ingredient needed. Use the table to record your research.

Ingredient	Weight in Grams	Relative Mass of One Serving
bread flour
coarse salt
cool water

Hypothesize the relationship between the products (number of bread servings) and the reactants (ingredients). Record your hypothesis in your notes.

Use the chart below from the chemistry lecture course to review how to recognize the chemical reactants.

**How to Recognize Types of Chemical Equations**
Type of Reaction	General Formula	How to Recognize
Combination reaction	A + B $LaTeX: \longrightarrow$ $\longrightarrow$ AB	Two or more reactants combine to form a single product.
Decombination reaction	CD $LaTeX: \longrightarrow$ $\longrightarrow$ C + D	A single reactant breaks down into multiple products.
Single replacement reaction	A + BX $LaTeX: \longrightarrow$ $\longrightarrow$ B + AX	An element which is more reactive takes the place of an element which is less reactive.
Double replacement reaction	CD + EF $LaTeX: \longrightarrow$ $\longrightarrow$ CF + ED	Two species are exchanged and result in the formation of two different compounds.
Combustion reaction	Organic Compound + $O_2$ $LaTeX: \longrightarrow CO_2+H_2O$ $\longrightarrow CO_2+H_2O$	This occurs when an organic compound reacts with oxygen to produce carbon dioxide and water.

What type of reaction occurs when you make the recipe?

What are the reactants in the recipe?

Identify the limiting reactant in the recipe.

Record in your notes why you hypothesized the cause of the reactions.

The actual recipe yields 8 servings. Use the equation that was given for percent yield in the chemistry lecture course, and calculate the percent yield.