Zinc Chloride & Sodium Hydroxide Experiment

By Raymond, David C, and David Y

Zinc Chloride(aq) + Sodium Hydroxide(aq) --> Zinc Hydroxide(s) + Sodium Chloride(aq)

Equation: ZnCl2(aq) + NaOH(aq) --> Zn(OH)2(s) + NaCl(aq)
Balanced equation: ZnCl2(aq) + 2NaOH(aq) --> Zn(OH)2(s) + 2NaCl(aq)

Aim:

To find out does less concentrated (more diluted) reactants produce more or less solid products.

Hypothesis:

The hypothesis is that less Zinc Hydroxide will be produced when the Zinc Chloride and Sodium Hydroxide solutions are less concentrated. According to the Collision Theory, the more reactants there are, the more collision will happen. Therefore more products will be produced.

Variables:

Independent variable - the amount of water (H2O) added to each reactant (the concentration)
Dependent variable - the amount and the volume of solid or gas products
Controlled variable - the same type of reactants (Zinc Chloride and Sodium Hydroxide)

Equipment and Materials:

  • Safety goggles
  • Funnel
  • Filter Paper (1.0M 1.2407 grams; 0.5M 1.2457 grams; 0.25M = 1.2588 grams)
  • Zinc Chloride (aq)
  • Sodium Hydroxide (aq)
  • Beakers
  • Graduated cylinders (10ml)
  • Erlenmeyer flasks
  • Water (H2O)
  • Distilled water bottle
  • Electronic balance
  • Spatula
  • Pipettes
Funnel.jpg
funnel
Graduated_Cylinder.jpg
Graduated Cylinder
Erlenmeyer_Flask.jpg
Erlenmeyer Flask
Pippette.jpg
Pipette
Beaker.JPG
Beaker
Electronic_Balance.jpg
Electronic Balance

Method:

  1. Measure 10ml of each reactants (Zinc Chloride or Sodium Hydroxide).
  2. Pour the two reactants into a beaker.
  3. Make a cone with the filter paper and put it in the funnel, and put the funnel on top of the flask.
  4. Pour the solution of Zinc Hydroxide and Sodium Chloride into the filter paper using a funnel and try to wash all the Zinc Hydroxide out of the beaker by adding water(H2O) using the distilled water bottle.
  5. Wait for one or two days until all the liquid and the solid are completely separated. Make sure that the solid is dry.
  6. Measure the mass of the solid Zinc Hydroxide with the filter paper.
  7. Repeat step 2 to 6 again and this time use only 5ml of each reactant and add 5ml of water to each reactant before mixing them together. (0.5M)
  8. Repeat step 2 to 6 again and this time use only 2.5ml of each reactant and add 7.5ml of water to each reactant before mixing them together. (0.25M)
  9. Finally, compare the differences between the results.
Reminder: Subtract the weight of the filter paper from the total mass!
DSCF0062.JPG
Filter Papers, Funnels, and Erlynmeyer Flasks
DSCF0069.JPG
The Reactants

Data Collection:

1 Molar:

Mass of filter paper = 1.2407 grams
Mass of filter paper and Zinc Hydroxide = 2.1464 grams
Mass of Zinc Hydroxide = 0.9057 grams

0.5 Molar:

Mass of filter paper = 1.2457 grams
Mass of filter and Zinc Hydroxide = 1.6832 grams
Mass of Zinc Hydroxide = 0.4375 grams

0.25 Molar:

Mass of filter paper = 1.2588 grams
Mass of filter paper and Zinc Hydroxide = 1.4514 grams
Mass of Zinc Hydroxide = 0.1926 grams

The amount and the volume of the product decreased after the dilution to the reactants was done.

Table: Concentration of Reactants (Molars) vs. Mass of Product (Grams)

m=molar
g=gram
Concentration ( m)
1.0
0.5
0.25
Mass of Filter Paper and Zinc Hydroxide (g)
2.1464
1.6832
1.4514
Mass of Filter Paper (g)
1.2407
1.2457
1.2588
Mass of Zince Hydroxide Produced( g)
0.9057
0.4375
0.1926

Data Processing:


Concentration_vs._Product_Graph.JPG


Conclusion:


The aim of this experiment was achieved. Less concentration yields less products. Also, the hypothesis made at the beginning of the experiment was correct because there was 0.9057 grams of Zinc Hydroxide when the concentration was one molar, and 0.4375 grams when the concentration was 0.5 molar, and 0.1926 grams when there was 0.25 molar. When the concentration is divided by half, the mass of products were also decreased by about half. So more Zinc Hydroxide was produced when less water was added to the Zinc Chloride and Sodium Hydroxide.

Evaluation:


Even though the experiment was mostly successful, there were experimental errors made. At first, the filter paper was used without being measured. The filter papers' weights differ from each other and this can affect the accuracy of the experiment. So the whole experiment was started over. And also, one the first attempt, a test tube was used instead of a beaker for performing the chemical reaction between the Zinc Hydroxide and Sodium Chloride. A lot of extra Zinc Hydroxide stuck on the side of the test tube and were not able to come off. When the solution was poured into the filter paper in the funnel, the solution wasn't properly poured. Some of the Zinc Hydroxide leaked through and gathered at the bottom of the flask along with the sodium chloride liquid.

The experiment was restarted and the second attempt was successful for all of the different concentrations. So the data collected is very accurate. And also precise because very precise instruments (graduated cylinder and electronic balance) were used to measure the amount of the Sodium Hydroxide and Zinc Chloride, and the Zinc Hydroxide which was produced.

A further question:

The experiment suggest another question after it was done, "Would the temperature of the water that was used to dilute the reactants affect the amount and the volume of the product? after increased the temperature of the the, wether the amount and the volume of the products increase or decrease?

Bibliography:


Peer Review for Group 9