Sept 15 th , 2014
SNC 2DW-03/04
CHCI
[Your Name]
Partners: [Your Partner(s)]
Teacher: Mrs. Quinney
Question:
What is the effect of changing the mass, in grams, of the reactants on the mass
(grams) of the products of a chemical reaction, using iron (III) nitrate solution and sodium hydroxide solution.
Hypothesis:
IF the mass of the reactants is successively increased, THEN the mass of the products will increase more than the reactants when a precipitate is formed, but less than the reactants when a gas is formed. These results are expected
BECAUSE… or
IF the mass of the reactants is successively increased, THEN the mass of the products will increase as well and will be the same as the original mass of the reactants, BECAUSE the same atoms are rearranged from reactants into products.
Variables:

The independent variable is the mass of the reactants of a chemical reaction, measured in grams. The volumes will be altered in order to change the

 mass. The total volumes that will be used include 14mL, 24mL, and 28 mL.
The dependent variable is the mass of the products of the reaction, measured in grams.
Important controlled variables include the: type of chemical reaction, temperature and time for reaction, reaction chamber, and equipment used.
The type of reaction will be controlled by using the same reactants for each trial: iron (III) nitrate solution and sodium hydroxide solution. The temperature will be kept the same by conducting the reaction at room temperature. Because matter moves faster at higher temperatures, this will help to ensure the reaction has went to completion (or the same point) in in each reaction. The reaction chamber will be kept sealed. The same electronic balance, flask and test tube will be used for all mass

measurements. Similarly, a graduated cylinder will be used for volume measurements.
Materials:







16 mL iron (III) nitrate solution (Fe(NO
3
)
3(aq)
)
50 mL sodium hydroxide solution (NaOH
(aq)
)
200mL Erlenmeyer flask small test tube (needs to fit in flask) stopper (needs to fit flask eg.#6)
10 or 25 mL graduated cylinder safety goggles

 waste container electronic balance
Method/Procedure:
1.
Put on safety goggles, as sodium hydroxide is corrosive.
2.
Begin the experiment at room temperature, and remain in the same room or in a room of similar room temperature for the duration of the data collection. (Could also monitor temperature with a thermometer!)
3.
Using the graduated cylinder, add 10 mL of sodium hydroxide into the flask.
4.
Rinse the graduated cylinder thoroughly with tap water and dry it with a paper towel.
5.
Using the graduated cylinder, add 4 mL iron (III) nitrate into the test tube, and place the test tube gently into the flask.
6.
Place the stopper securely in the flask to create a closed reaction chamber.
7.
Observe and record the physical properties of the solutions.
8.
Using the electronic balance, measure the mass of the reactants
(including the equipment). Record the mass in grams.
9.
Tip the flask so that the solutions mix.
10.
Using the electronic balance, measure the mass of the products
(including the equipment). Record the mass in grams.
11.
Observe and record the physical properties of the products.
12.
Empty the flask and test tube into the waste container, thoroughly rinse the equipment with tap water and dry it with paper towels.

13.
Repeat steps 2-11 for a total of 3 trials, by recording two other groups’ data.
14.
Repeat step 2-12, but add 20 mL of sodium hydroxide into the flask.
15.
Repeat step 2-12, but add 8 mL of iron (III) nitrate solution into the test tube and add 20 mL of sodium hydroxide into the flask
Observations
Table 1. Physical Properties of Reactants and Products Before and After
Mixing
Reactants
Physical Properties
Reactants (before mixing) Products (after mixing) iron (III) nitrate sodium hydroxide state: liquid clarity: clear colour: orange state: liquid clarity: clear colour: colourless state: liquid & solid clarity: cloudy colour: orange-brown
Table 2. Masses of Reactants and Products Before and After Mixing Different
Volumes of Reactants
Mass (g)
Reactant Volume (mL)
Trial
#
Reactants (and apparatus)
Products (and apparatus) iron (III) nitrate: 4 sodium hydroxide: 10
1
2
3
146.5
166.1
166.1
146.5
166.1
166.2 iron (III) nitrate: 4 sodium hydroxide: 20 iron (III) nitrate: 8
1
2
3
1
157.4
174.8
176.8
161.3
157.5
174.6
176.8
161.3

sodium hydroxide: 20
2
3
180.9
180.6
180.9
180.6
Analysis:
Sample calculation (for 4 mL of iron (III) nitrate and 10 mL of sodium hydroxide): mean mass =
= mass
158.3
1 g
+ mass
2
+ mass number of masses
3
=
164.5
g
+
150.3
3 g
+
160.0
g
Table 3. Mean masses of reactants and products before and after mixing
Reactant Volume (mL)
Mean Mass (g)
Reactants (and apparatus)
Products (and apparatus) iron (III) nitrate: 4 sodium hydroxide: 10
158.3 158.2 iron (III) nitrate: 4 sodium hydroxide: 20 iron (III) nitrate: 8 sodium hydroxide: 20
158.3
156.7
158.2
156.6
See Figure 1 (page 9) for a bar graph comparing the mean masses of reactants and products.

160
140
120
200
Reactants
Products
180
100
80
60
40
20
0
14 24 28
Total Volume of Reactants (mL)
Questions:
1.
After the reaction, the clarity change indicated that a precipitate formed; furthermore, the formation of the orange-brown solid indicated a colour change.
2.
iron (III) nitrate + sodium hydroxide  iron (III) hydroxide + sodium nitrate
Conclusion:
The mass of the reactants is the same as the mass of the products for chemical reactions. The small difference between reactants and products (0.1 g) is not significant compared to the size of the overall mass, as is evident in Figure 1, where for all volumes the bars appear the same size for reactants and

products. Furthermore, Figure 1 shows an equal increase in product mass for increased reactant mass which supports the hypothesis.
As is evident from the masses, the atoms of reactants simply rearrange into product substances, and is supported using the Law of Conservation of Mass from ON science textbook (Dickenson, 2009) which can be represented by the following balanced chemical equation:
Fe(NO
3
)
3(aq)
+ 3 NaOH
(aq)
 Fe(OH)
3(s)
+ 3 NaNO
3(aq)
(The mean masses for all three volumes had the products 0.1g less than the reactants. However, we would consider this difference insignificant compared to the overall mass of the reactants, especially considering experimental errors that may occur, such as transfer of water or dirt from hands to the flask between mass measurements.)
Evaluation:
The flask may have had water on it when the mass was measured, so if it has less water from when the reactants were measured to when the products were
measured, then the products mass would be lower than it should be.
The flask should be dried on the outside after being rinsed before performing the next reaction.
This investigation’s method did not include a reaction that produces a gas, which may create a difference in mass between reactants and products as a gas tends to be a less dense state of matter . A sealable metal container with a screwtop lid should be used for such a reaction involving, for example, vinegar and baking soda as reactants.
Reference:
Dickinson, Tom. 2009. ON Science 10. McGraw-Hill Ryerson. Whitby. p160-
165,172