C2 P2: Reaction equations lecture 2.

• Scheikunde
• Middelbare school
• havo
• Leerjaar 3

C2 lecture 2: Reaction equations  

Learning objectives:

1. You can use the phase symbols for substances.
2.  You can use a description of a chemical reaction to work out the reaction equation.   
   

Reaction equation

What do you remember of the last lecture? 

what are the 5 steps to balance a reaction equation ? 

From reaction to equation 

From reaction to equation

Step-by-step plan to a correct reaction equation.

Step 1. Write down the word equation.

Step 2. Replace the names of the substances by their formulas

Step 3. Balance the reaction equation.

- Check which type of atoms appear at 2 places. Choose one of them and put coefficients in front of those two formulas to have the same amount of the chosen type of atom on both sides.

- Choose the lowest numbers possible. What always works (but is not always the lowest): 3 x 2 = 2 x 3

- Continue with the next type of atom. Choose one of which you are only missing 1 coefficient.

- When u have a fraction instead of  a whole number, multiply all coefficients until you do by the denominator (number below)

From reaction to equation

Step-by-step plan to a correct reaction equation.

Step 4. Check if you can simplify the reaction equation. If possible, you must do so.

Step 5. Double check if every molecular formula has a coefficient. Remove all coefficients that are equal to 1. When a molecule appears only once, the coefficients is not written down in your final answer.

Example    

Step 1. 

Step 2. 

Step 3a. 

Step 3b. 

Step 4.  

Step 5. 

Lets work!

Do you have questions about the home work ? 

Make: Exercises 1 through 6.

Homework HT3a

Read: Chapter 2 paragraph 2. Reaction equations 

Make: All the exercises. 

Lets work!

Do you have questions about the home work ? 

Make: Exercise 3.

Homework HT3b

Read: Chapter 2 paragraph 2. Reaction equations 

Make: Exercises 1 through 3.