Group+6

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Title:
How does the concentration of the reactant affect the mass of the product?

Research Question:
The aim for this experiment is to investigate how does the change of the concentration of the copper sulphate affect the mass of the copper hydroxide that can be formed in the following chemical reaction. Copper sulphate(aq) + sodium hydroxide(aq) ---> copper hydroxide(s) + sodium sulphate(aq) CuSO4 + 2NaOH > Cu(OH)2+ Na2SO4

Hypothesis:
Based on the Collision Theory, as the concentration of the reactant decreases, there will be less collision taking place between the particles. Thus, the speed of the reaction will decrease as well. So a hypothesis can be drawn: as the concentration of the copper sulphate and the the sodium hydroxide decreases, the speed of the reaction will decrease. As a result, less solid copper hydroxide will be formed.

Variables:

 * Independent variable: the concentration of the copper sulphate
 * Dependent variable: the mass of the solid copper hydroxide
 * Controlled/constant variables: the concentration of the sodium hydroxide, the temperature, the sizes of the erlenmyer flask and the graduated cylinders the volume of the sodium hydroxide and the copper sulphate.

Materials:

 * [|copper sulphate(aq)]
 * [|sodium hydroxide(aq)]
 * [|1 80ml beaker]
 * [|4 filter paper]
 * [|4 filter funnel]
 * [|electronic balance]
 * [|4 200ml erlenmyer flask]
 * [|distilled water]
 * [|2 50ml cylinders]
 * [|2 pipette]

Method:
1. Pour 10ml of copper sulphate and 10ml of sodium hydroxide into two different graduated cylinders. That is the first trial for the experiment in which the concentration of the copper sulphate is 1.0 molar.

2. Pour the 10ml of sodium hydroxide into the 80ml beaker, then slowly pour the 10ml of copper sulphate into the beaker as well.

3. Measure the masses of the 4 filter paper and record each of them down.

4. Fold 1 filter paper and place it into a filter funnel; put the filter funnel into an erlenmyer flask.

5. Slowly pour the mixture of the sodium hydroxide and the copper sulphate into the filter paper.

6. Cleanse the two graduated cylinders and the beaker

7. For the second trial of this experiment, pour 7.5ml of copper sulphate into one graduated cylinder. Add 2.5ml of distilled water to the copper sulphate. In this case, the concentration of the copper sulphate is 0.75 molar. Pour 10ml of sodium hydroxide into the other graduated cylinder.

8. Pour 10ml of sodium hydroxide into the beaker, then slowly pour in the diluted 10ml of copper sulphate.

9. Repeat steps 4, 5 and 6 for the second trial.

10. In the third trial. The concentration of the copper sulphate will be changed to 0.5 molar. So pour 5ml of copper sulphate into the graduated cylinder and then add 5ml of distilled water to it. Pour 10ml of sodium hydroxide into the other graduated cylinder.

11. Pour the 10ml of sodium hydroxide into the beaker, slowly add the 0.5 molar copper sulphate into it.

12. Repeat steps 4, 5 and 6 for the third trial.

13. For the fourth trial, pour only 2.5ml of copper sulphate into the graduated cylinder and add 7.5ml of distill water to it. As a result, the concentration of the copper sulphate in this trial will only be 0.25 molar. Pout the 10ml of sodium hydroxide into the other graduated cylinder as well.

14. Pour the 10ml of sodium hydroxide into the beaker, and then slowly pour in the 0.5 molar copper sulphate.

15. Repeat steps 4, 5 and 6.



Qualitative observation:
The chemical reaction that is formed between the copper sulphate and the sodium hydroxide can be seen during the experiment. When the dark blue copper sulphate solution is added to the white sodium hydroxide solution, some cotton-like, blue color solid is formed. The solid is called the copper hydroxide. The copper hydroxide is within a solution called the sodium sulphate.

Conclusion:
The aim is achieved by doing this experiment. Our hypothesis is correct. The experiment shows that as the concentration of the copper sulphate decreases by dilution, the mass of the copper hydroxide also decreases. When the concentration of the copper sulphate is 1.00 molar, the mass of the copper hydroxide is 0.378 grams. As the concentration of the copper sulphate decreases to 0.75 molar, 0.5 molar and 0.25 molar, the masses of the copper hydroxide also decreases to 0.368 grams, 0.246 grams and 0.156 grams respectively.

Evaluation:
Some modifications can be made to this experiment in order to make the results more accurate and precise. For example, one can do more trials in the experiment in order to add more points on the line of best fit. The precision of the data can also be increased by doing additional trials which one can change the concentration of the sodium hydroxide instead of the concentration of the copper sulphate in the experiment. The final results can then be used to further check and evaluate the reliability of the hypothesis. When one is doing the experiment, one should try to regulate the speed in which one pours in the copper sulphate to the sodium hydroxide. That can improve the precision and the accuracy of the final results. In addition, in the process of filtering, some solid copper hydroxide is not fully seperated from the sodium sulphate solution due to the quality of the filter paper. This will also cause some errors in the final results. In order to explore how different factors can change the speed of a chemical reaction, one can also do different experiments related to this topic. For example, one possible question that one can further investigate on may be how the temperature can change the speed of a chemical reaction. Therefore, instead of changing the concentration, one can change the temperature(s) of the reactant(s) and explore the effects that temperature has on the speed of the chemical reaction.