This is ACA # 2, our first ACA of the Fall semester. It is OK to use your textbook, but if you can answers the questions without it that is OK too.

I recommend you print out this page and bring it to class. Click here to show a set of five ACA2 student responses, randomly selected from all of the student responses thus far, in a new window.


, here are your responses to the ACA and the Expert's response.

1. Consider the contents of Container A and complete parts a - d below.

Contents of Container A: , , ,

This container shows a diatomic element (a pure substance) in the gas phase.

2. Consider the contents of Container B and complete parts a - c below.

Type of mixture in Container B:

The blue component: , ,

the green component: , ,

The container shows an element in the solid phase (green color) in a liquid phase of another element (blue). The solid is undissolved, so this is a heterogeneous mixture. (NOTE: If the solid dissolved the mixture would be homogeneous.)

3. Consider the contents of Container C and Container D and complete parts a - b below.

Type of change:

Chemical equation that describes the reaction is:

The container on the left (reactants) shows a compound (yellow atom with two red atoms covalently bonded to it) and an element (the diatomic red molecule). Both substances are gases so the mixture is homogeneous. The container on the right has a new compound (yellow atom with three red atoms covalently bonded to it) and an element (the same diatomic molecule found in the container on the left). These two containers taken together represent a chemical reaction. Why are there only three diatomic molecules in the right container?

4. Without looking at your textbook complete the following table about elements;

Symbol

Name

Formula

Phase (at 25 °C)

Al


aluminum


Al


solid

N


nitrogen


N2


gas


Br

bromine


Br2


liquid

 

5a. Describe what happened when the piece of sodium metal is added to the chlorine gas? (Note: Here is another movie of the reaction.) (Here is the link to the page in your VitaSource ebook.) Either movie will be opened in a new window. After watching the movie close the window to get back to the ACA. (If the movie does not work see page 42 in your textbook.)

(NOTE: The video is in QuickTime format so you must have that player. I recommend getting iTunes as it also has the QuickTime Player. Also with iTunes you will be able to subscribe to the CHEM 1314 video podcasts that contain lectures, problem solving videos and other cool features. See the Announcements Page for more info on podcasts.)

When the solid, silvery sodium metal was added to greenish-yellow an immediate reaction occurred as evidenced by the bright yellow flame that appeared in the container. As the yellow flame diminished a white cloud of sodium chloride was observed.

b) Write a chemical equation to describe the reaction in Q5a. (NOTE: Your chemical equation should use formulas for the reactants and for the product, and each substance's phase should be identified as (g)as, (l)iquid, (s)olid or (aq)ueous.)

2Na(s) + Cl2(g) ----> 2NaCl(s)

6. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

7. If there is one question you would like to have answered in lecture, what would that question be?