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 * __Grade 9 Chemical Reactions Lab Report__****: Experimenting with LEAD IODIDE!**

__**Research Question:**__
Does changing the concentration of potassium iodide change the mass of lead iodide formed in the chemical reaction between lead nitrate and potassium iodide?



**__Hypothesis:__**
As the concentration of the reactant (potassium iodide) decreases, the mass of the product (lead iodide) will decrease. This hypothesis is based on the collision theory that states that a chemical reaction occurs by particles colliding with each other. The less of the amount of a reactant there is, the less of the product formed.

**__Variables:__**
//Independent Variable:// The concentration of potassium iodide. //Dependent Variable:// The mass of the lead iodide //Control Variable:// the amount of lead nitrate, the type of filter paper.

**__Materials:__**
-Two 80ml beakers -Five Filter paper -30mL Potassium iodide -50mL Lead nitrate -20nL Distilled Water -5 Funnels -5 [|Erlenmeyer flasks] -Electronic balance -Safety Goggles

**__Method:__**
1. Label the funnels with the molar masses of each reactant (potassium iodide and lead nitrate) 2. Place the labeled funnels in the Erlenmeyer flasks. 3. Measure 10 mL of 1 M of potassium iodide in a measuring cylinder and pour it into the 80ml beaker. 4. Measure 10 mL of 1 M of lead nitrate in a measuring cylinder and pour it into another 80ml beaker. 5. Pour potassium iodide into the lead nitrate beaker, wait until the product changes color. 6. Pour the products of the reaction into the respectively labeled funnels through the filter paper to filter out the solid lead iodide only. 7. Repeat steps 3-5 with the different molar masses of potassium iodide (0.8 M, 0.6 M, 0.4M, 0.2M) 8. Measure and record the mass of the filter paper using the electronic balance. 9. Leave the five amounts of lead iodide to dry overnight so that the products have as least amount of water in them as possible. Make sure they are clearly labeled. 10.Record the mass of the lead iodide minus the mass of the filter paper.

**__Data Collection and Processing:__**
Qualitative observations: As the concentration of potassium iodide decreased, there was a visible change in the amount of lead nitrate produced.

Table 1

Figure 1
 * __Data Processing:__**

**__Conclusion:__**
Based on the data and observations, the aim of this experiment has been achieved. The purpose was to find out whether or not changing the concentration of potassium iodide would affect the mass of the lead iodide (the product). By changing the molar mass of the reactant, the mass of the product changed as well. The concentration of the potassium iodide and the mass of the lead iodide have a positive relationship. When the concentration of the potassium iodide decreases, the mass of the lead iodide also decreases. From the data collected, the results of the experiment support what was predicted by the hypothesis. The hypothesis stated that as the molar mass of the reactant decreases, the mass of the product will decrease as well.



**__Evaluation:__**
There are several things that could have been changed in this experiment. For example, to measure the amount of water to increase the concentration in potassium iodide measuring cylinders were used but many errors could have been made with accuracy, such as placing the cylinder on a slanted surface or not taking care to measure below the meniscus. More care could have been taken with our materials. While filtering the solid lead iodide from the flasks, some slipped through the sides of the filter paper, meaning some of the precipitant was lost and the results would have been less accurate. It was challenging to keep a record of which concentration amount in the potassium iodide was in each flask, but the flasks were clearly labeled and clear data was therefore recorded. To have more accurate results this lab could have been experimented with more molar amounts—rather than 1, 0.8, 0.6, 0.4, and 0.2, the concentration could be tested with molar masses of 0.1, 0.2, 0.3, 0.4, etc all the way up to 1 M. If the opportunity arose to investigate this further, it would be interesting to vary the concentration amounts in lead nitrate as well. Also, one could alter other aspects of the experiment than concentration—like changing the external temperature surrounding the chemical reaction.