Category: Chemistry

2. The measurement of the amount of matter in an object is called ___________________.

3. What are the 3 states of matter?

    A.____________________________________
B.____________________________________
C.____________________________________

4. Charged particles that move around an atom’s nucleus are called ________________________.

5. Chemical bonds are broken, atoms are rearranged, and new bonds are formed during ___________________________  ______________________________.

6. Atoms with filled outermost energy levels tend _____________ to participate in chemical reactions.

7. A pure substance that cannot be broken down is called an ____________________.

8. The simplest part of an element is an ____________________.

9. The central core of an atom is called the _____________________________.

10. In an ionic bond, __________ atoms of ________________ charge are held together by _________________________ attraction.

11. The part of an atom that has a neutral charge is a _______________________.

12.  Most of the mass of an atom is found in the _____________________.

13. A pure substance made up of atoms of one or more elements is called a ____________________________.

14.  Most atoms tend to undergo ____________________  _________________, combining in ways that cause their atoms to become more ____________________.

15. When two atoms share one or more electrons, it is called ____________________________  ______________________.

16.   A bond formed by electrical attraction between two opposite charged ions is called ______________________  ____________________.

17.   The ability to do work or cause change is _____________________.

18.   A redox reaction involves the _____________________ of ___________________ between atoms.

19. The amount of energy needed to start a chemical reaction is the reaction’s _________________________  ___________________.

20. A substance that neutralizes small amounts of acids or bases added to a solution is a _______________________.

21. A chemical reaction that can proceed forward or backward is a ______________________  ______________________.

22.  Sodium chloride (table salt) is an example of a compound formed by ______________ _________________.

23.  The positive charge part of an atom is called a ___________________________.

24.   A particle composed of one or more atoms is a ________________________.

25.  Chemical reactions that release free energy are called ____________________________ ____________________________.

26.   Chemical reactions that absorb free energy are called ____________________________ _______________________________.

27.   The loss of one or more electrons is called ______________________.

28.   The gaining of one or more electrons is called _______________________.

29.   The breaking apart of water molecules into two ions of opposite charge is called ___________________________________.

30.   An atom has six electrons, what is it atomic number? ____________  Name?___________  It is a stable or unstable atom? _________________.

31.   Why is it necessary for oxidation and reduction reactions to occur in pairs?

32. What is the role of enzymes in chemical reactions occurring in living things?

33. Describe the relationship between the solute, the solvent, and the concentration of a solution.

34. List 2 characteristics of acids and 2 characteristics of bases.

35.  What is the pH Scale, and what does its range of values mean?

Introduction:

A pH indicator is a chemical compound that is added in small amounts to a solution so that the pH (acidity or basicity) of the solution can be determined visually. Hence a pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+) on the pH scale.  Normally, the indicator causes the color of the solution to change depending on the pH.  At 25 degrees Celsius, considered the standard temperature, the pH value of a neutral solution is 7.0. Solutions with a pH value below 7.0 are considered acidic, whereas solutions with pH value above 7.0 are basic.

Objectives:

• to observe chemical reactions.
• to observe changes in pH.
• to do a burning splint test to check for oxygen production.

Materials:

* You can substitute  Phenolphthalein with Cabbage Juice.  Follow instructions for Cabbage Juice as indicated.

Procedure Bag 1:

1. Place 2 tsp of baking soda into the bag.
2. Add 30 mL of Phenolphthalein to the bag. (Skip this step if you are using Cabbage Juice)
3. Massage the bag to mix the contents.
4. VERY CAREFULLY – lower the test tube containing 30 mL of water upright  into the bag.  (OR Lower a small cup or beaker with 50 ml of Cabbage Juice as a substitute). Do not let any spill out.
5. Have a student help you hold the test tube by squeezing the test tube gently from the outside of the bag while you squeeze the excess air out and seal the bag.
6. Hold the test tube and bag up and slowly spill the water out of the test tube (while the bag is still sealed).  The contents will turn bright pink. Cabbage Juice will turn greenish blue for a base and purplish for neutral, pink for acid
7. Pass the bag around and have other students look at and feel the contents of the bag.  At this point, they will see the baking powder dissolving and the contents turning pinker.

Procedure Bag 2:

1. Place 2 tsp of calcium chloride into the bag.
2. Add 30 mL of Phenolphthalein to the bag. (Skip this step if you are using Cabbage Juice)
3. Massage the bag to mix the contents.
4. VERY CAREFULLY – lower the test tube containing 30 mL of water upright  into the bag.  (OR Lower a small cup or beaker with 50 ml of Cabbage Juice as a substitute) Do not let any spill out.
5. Have a student help you hold the test tube by squeezing the test tube gently from the outside of the bag while you squeeze the excess air out and seal the bag.
6. Hold the test tube and bag up and slowly spill the water out of the test tube (while the bag is still sealed).  The contents will turn bright pink and start to get warm. Cabbage Juice will turn greenish blue for a base and purplish for neutral, pink for acid
7. Pass the bag around and have students look at and feel the contents of the bag.  At this point, they will see the calcium chloride dissolving and the contents turning pinker and getting warmer.

Procedure Bag 3:

1. Place 2 tsp of baking soda into the bag.
2. Place 2 tsp of calcium chloride.
3. Add 30 mL of Phenolphthalein . (Skip this step if you are using Cabbage Juice)
4. Massage the bag to mix the contents.
5. VERY CAREFULLY – lower the test tube containing 30 mL of water upright  into the bag.  (OR Lower a small cup or beaker with 50 ml of Cabbage Juice as a substitute)  Do not let any spill out.
6. Have a student help you hold the test tube by squeezing the test tube gently from the outside of the bag while you squeeze the excess air out and seal the bag.
7. Hold the test tube and bag up and slowly spill the water out of the test tube (while the bag is still sealed).  The contents will turn bright pink. Cabbage Juice will turn greenish blue for a base and purplish for neutral, pink for acid
8. Pass the bag around and have students look at and feel the contents of the bag.  At this point, they will see the baking powder and calcium chloride dissolving, foaming, bubbling, instead of pink, it will become clear/white, and the bag will be warm.  As the bag is passed around, it will start to inflate and puff out.

At this point, you will have all 3 bags on your table.  You can have the students compare the 3 bags and discuss what is the same, what is different, why it was important that you did the same procedure for each bag etc.  Have students try to guess why the 3rd bag is puffy and not pink, etc.

Procedure – Part 2:

1. After you have discussed what happened in the three bags, light a match for your group.
2. While someone holds the wooden splint,  light the splint with the match.
3. Have another student hold the 3rd bag.
4. Tell the student to open the bag then you will quickly place the burning splint into the bag.

Observations Part 1:

Observations – Part 2

What happened when you placed the splint into the 3rd bag? Why? 

Analysis and Results:

1. Was there a change in pH?  How do you know?
2. What happened to the contents of the bags?
3. Without opening the bags, how can you tell if a gas was produced?
4. This equation tells us what chemical reaction happened in the bag.  Identify and count the elements on each side of the “yield” sign:

2NaHCO3 + CaCl2 ———–> CaCO3  + 2NaCl  + H2O + CO2

5. Place a CIRCLE around the Calcium Chloride.  Place a SQUARE around the Salt. Place a TRIANGLE around the Water.
6. What gas was produced in this reaction?
7. Was there a change in temperature?  How can you tell?

Teacher Notes:

• You might want to use more sturdy bags if you pass them around. As the students massage the bag, small tears in the bag may occur.  The 3rd bag may burst, it gets pretty full and tight.
• The Phenolphthalein turns pink in a base and clear for an acid/neutral.
• Cabbage Juice will turn greenish blue for a base and purplish for neutral, pink for acid
• Do NOT  do a flame test for bags 1 & 2, it will ignite.  (Phenolphthalein is flammable)
• Click for MSDS info for  Phenolphthalein : https://fscimage.fishersci.com/msds/96382.htm

This lab was modified from the original lesson:  http://www.science-house.org/learn/CountertopChem/exp5.html

1.  Explain how carbon’s electron configuration accounts for its ability to form large, complex, and diverse organic molecules.

2.  Describe how carbon skeletons may vary, and explain how this variation contributes to the diversity and complexity of organic molecules.

3.  Describe the basic structure of a hydrocarbon and explain why these molecules are hydrophobic.

4.  Distinguish among the three types of isomers: structural, geometric, and enantiomer.

Functional Groups

5.  Name the major functional groups found in organic molecules. Describe the basic structure of each functional group and outline the chemical properties of the organic molecules in which they occur.