Stoichiometry
WTan12 Syn Pondering » ict10bertoia
Title
Stoichiometric relationship between the quantities of Pb(NO3)2, NaI, PbI2, and NaNO3 in a chemical reaction
1. Pb(NO3)2 + 2NaI —-> PbI2 + 2NaNO3
2. and 3.
| Group Number | Mass Pb(NO3)2 | Mass
NaI |
Mass
PbI2 |
Moles Pb(NO3)2 | Moles NaI | Moles PbI2 |
| 1 | 1.66g | 0.75g | 1.64g | 0.005 | 0.005 | 0.0036 |
| 2 | 1.66g | 0.90g | 1.02g | 0.005 | 0.006 | 0.0022 |
| 3 | 1.66g | 1.05g | 1.15g | 0.005 | 0.007 | 0.0025 |
| 4 | 1.66g | 1.20g | 1.25g | 0.005 | 0.008 | 0.0027 |
| 5 | 1.66g | 1.35g | 1.57g | 0.005 | 0.009 | 0.0034 |
| 6 | 1.66g | 1.50g | 1.66g | 0.005 | 0.01 | 0.0036 |
| 7 | 1.66g | 1.65g | 2.11g | 0.005 | 0.011 | 0.0046 |
| 8 | 1.66g | 1.80g | 2.22g | 0.005 | 0.012 | 0.0048 |
| 9 | 1.66g | 1.95g | 2.12g | 0.005 | 0.013 | 0.0046 |
| 10 | 1.66g | 2.10g | 2.18g | 0.005 | 0.014 | 0.0047 |
4.
5. The graph shows the relationship between the quantities of lead iodide (PbI2) produced according to the mass of sodium iodide (NaI) given. By observing the graph, we can see that starting from 0.006 to 0.0011 moles of sodium iodide, the quantity of moles of lead iodide is increasing from 0.0022 to 0.0046. On the other hand, we can also see that from 0.0011 to 0.0014 moles of sodium iodide, the line that represents the quantity of moles of lead iodide is fairly flat, in comparison to the escalating, steep line from 0.006 to 0.0011 moles of sodium iodide. The last 1/3 of the graph maintains a quite flat line because when the moles of sodium is present from 0.0011 moles onwards, sodium iodide’s role changes from the limiting reactant to the reactant that is present in excess and lead nitrate (Pb(NO3)2) becomes the limiting reactant. As it is lead nitrate that affects the amount of lead iodide produced in the last 1/3 of the experiment, the amount of lead iodide produced does not have a huge difference because the amount of lead nitrate present remains constant throughout the whole experiment, which is having a mass of 1.66g or moles of 0.005. In conclusion, when sodium iodide is present from 0.006 to 0.011 moles, sodium iodide is the limiting reactant, thus the quantity of moles of lead iodide increases from 0.0022 to 0.0046. When sodium iodide is present from 0.0014 moles, lead nitrate becomes the limiting reactant; hence the quantity of moles of lead iodide doesn’t change much because lead nitrate is present with the amount of 0.005 moles throughout the experiment.
6. (a) Pb(NO3)2 (lead nitrate) is the reactant that is present in excess.
(b) NaI (sodium iodide) is the limiting reactant.
Predicted mass of PbI2 using Pb(NO3)2
Calculations:
1.66/331.2074 = x/1 –> x = 1.66/331.2074 = 0.005 mol Pb(NO3)2
Since ratio is 1 to 1, the mol stays the same. (0.005 mol PbI2)
0.005/1 = x/461.008 –> x = 461.008 * 0.005 = 2.305 g
Predicted mass of PbI2 using NaI
Calculations:
If NaI = 0.75g, PbI2 = 1.153 g
If NaI = 1.35 g, PbI2 = 2.074 g
For group numbers 1-5, Pb(NO3)2 always produces 2.305g of PbI2 whilst NaI produces a range of 1.153g to 2.074g of PbI2. This shows that NaI will always produce less than PbI2 than Pb(NO3) 2, thus it is the limiting reactant.
7. (a) The NaI (sodium iodide) is the reactant that is present in excess.
(b) The Pb(NO3)2 (lead nitrate) is the limiting reactant.
Predicted mass of PbI2 using Pb(NO3)2
Calculations:
1.66/331.2074 = x/1 –> x = 1.66/331.2074 = 0.005 mol Pb(NO3)2
Since ratio is 1 to 1, the mol stays the same. (0.005 mol PbI2)
0.005/1 = x/461.008 –> x = 461.008 * 0.005 = 2.305 g
Predicted mass of PbI2 using NaI
Calculations:
If NaI = 1.65g, PbI2 = 2.536g
If NaI = 2.10g, PbI2 = 3.227g
For group numbers 7-10, Pb(NO3)2 always produces 2.305g of PbI2 whilst NaI produces a range of 2.536g to 3.227g of PbI2. This shows that NaI will always produce more PbI2 than Pb(NO3)2, thus it is the reactant that is present in excess.
8. The mole ratio of Pb(NO3)2 : NaI for group number 6 is 1 : 2. Because of the ratio, there is no limiting reactant for group number six. As the mole ratio of Pb(NO3)2 : NaI : PbI2 is 1 : 2 : 1, so the moles of PbI2 predicted will always be 0.005. As a result, the shape of the graph when NaI is 0.01 moles is affected equally by number of moles of NaI and Pb(NO3)2.
Science – Stoichiometry experiment questions
Chris Choi Chris » ict10bertoia
Processing of results and questions of stoichiometric experiment
- In the class, we learned about stoichiometry and an experiment of NaI and PbI2 was given to investigate more about stoichiometry.
1/ Pb(NO3) 2 + 2NaI => PbI2 + 2NaNO3
2 /
| Group | Mass of NaI(g) | Mass of PbI2 (g) |
| B1 | 1.95 | 2.12 |
| B2 | 1.05 | 1.15 |
| B3 | 1.65 | 2.11 |
| B4 | 1.5 | 2.21 |
| G1 | 1.35 | 1.62 |
| G2 | 1.5 | 1.66 |
| G3 | 1.8 | 2.22 |
| G4 | 1.22 | 1.25 |
| G5 | 2.1 | 2.18 |
| G6 | 0.75 | 1.64 |
| H1 | 1.95 | 2.24 |
| H2 | 1.35 | 1.57 |
| H3 | 0.9 | 1.02 |
3/
| Group | Mass of NaI(g) | Mass of PbI2 (g) | Moles of NaI(g) | Moles of PbI2 (g) |
| B1 | 1.95 | 2.12 | 0.013 | 0.005 |
| B2 | 1.05 | 1.15 | 0.007 | 0.002 |
| B3 | 1.65 | 2.11 | 0.011 | 0.005 |
| B4 | 1.5 | 2.21 | 0.01 | 0.005 |
| G1 | 1.35 | 1.62 | 0.009 | 0.004 |
| G2 | 1.5 | 1.66 | 0.01 | 0.004 |
| G3 | 1.8 | 2.22 | 0.012 | 0.005 |
| G4 | 1.22 | 1.25 | 0.008 | 0.003 |
| G5 | 2.1 | 2.18 | 0.014 | 0.005 |
| G6 | 0.75 | 1.64 | 0.005 | 0.004 |
| H1 | 1.95 | 2.24 | 0.013 | 0.005 |
| H2 | 1.35 | 1.57 | 0.009 | 0.003 |
| H3 | 0.9 | 1.02 | 0.006 | 0.002 |
4/
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5/ The graph clearly shows the molar ratio between NaI and PbI2; x amount of NaI produces with y amount of PbI2. For example, 0.014 moles of NaI will produce roughly about 0.005 PbI2.
6/ a) PB(NO3)2 is the reactant in present in excess because Nal is the limiting reactant since Nal produces less PbI2 than PB(NO3)2 does.
b) NaI is the limiting reactant.
6/ For group number 1-5
- Pb(NO3) 2 is the reactant in excess.
- NaI is the limiting reactant
For example, taking a look at group number 5:
- Mass Pb(NO3) 2 : 1.66 g
- Mass NaI: 1.35 g
Pb(NO3) 2 + 2NaI => PbI2 + 2NaNO3
Pb(NO3) 2 : 0.005 (mol) => Creating mol of PbI2
NaI: 0.009 (mol) => Creating mol of PbI2
mol > mol:
ð NaI is the limiting reactant and Pb(NO3) 2 is the reactant in excess
7/ For group number 7-10
- NaI is the reactant in excess.
- Pb(NO3) 2 is the limiting reactant
For example, taking a look at group number 7:
- Mass Pb(NO3) 2 : 1.66 g
- Mass NaI: 1.65 g
Pb(NO3) 2 + 2NaI => PbI2 + 2NaNO3
Pb(NO3) 2 : 0.005 (mol) => Creating mol of PbI2
NaI: 0.011 (mol) => Creating mol of PbI2
mol > mol:
ð Pb(NO3) 2 is the limiting reactant and NaI is the reactant in excess
Rates of reaction Lab report
AVo12 That's the way I like it... :) » ict10bertoia
I found this experiment very interesting and fun at the same time. By doing it, I found out how the rate of reaction of the magnesium is affected by the three experiments.
Jin Kyung Lee, Amy Vo, Mano Ramos
Chemistry
Mr. Mac
23rd February 2010
An investigation of Magnesium and its rate of reaction regarding temperature, surface area, and concentration
The rates of reaction by the three different experiments: Surface Area, Temperature and Concentration
Problem:
Compiling our data from each of the three experiments (Surface Area, Temperature, and Concentration) to find out how the rate of reaction of the magnesium is affected by the three experiments.
Hypothesis:
How do the three different experiments affect the rates of Reaction?
There is something that needs to be introduced: The Collision Theory. This theory emphasizes that reactions happen when particles collide with each other. This is supported by the results of the experiments on the effect of temperature, surface area and the concentration on reaction rates.
A more concentrated solution means that there are more reactant particles in a given space (volume), therefore collisions will occur more often. The more often they collide, the more chances they have of reacting. This means that the rate of a chemical reaction will increase if the concentration of the reactants is increased.
At higher temperatures, the particles tend to move faster, again this means that there will be more collisions occurring, giving more chances of reaction. Also, the particles have more energy at the higher temperature. So when temperature is raised, a reaction takes place faster.
So therefore we predict that all these three experiments will change the rate of reactions. Higher the temperature the faster it would react, more concentrated the solution faster reaction and the smaller the surface area the faster the reaction.
Materials:
• Water ( HOT & COLD -includes ice)
• Temperature controller
• Magnesium
• 2 Pipettes
• 2 Beakers
• Stop watch
• 3 Goggles
• 10 mL Hydrochloric Acid ( 1.5 Mol ) ( for concentration experiment )
• 10 mL Hydrochloric Acid ( 0.5 Mol ) ( for concentration experiment )
• 20 mL Hydrochloric Acid ( for the surface area experiment)
• 2 Test tubes, Label A and B
• Thermometer
Procedure:
Temperature:
1. Retrieve two pieces of Mg for both the hot and cold water temperature tests.
2. For the cold water temperature test, drop the Mg piece in the test tube placed in cold water.
3. Observe closely and time as soon as the piece is dropped in the test tube.
4. As you time it, observe the Mg piece. When it starts to react, take note of the time.
5. If it goes over 5 minutes, then stop the timer and record observations – appearance, odor and color.
6. Repeat steps 2-5 for hot water.
Surface area:
1. Retrieve the C6H5COOH (Benzoic Acid).
2. Put the same amount of Benzoic Acid into two separate test tubes.
3. Put one piece of rolled Mg (Magnesium) into one tube.
4. Put one piece of flat Mg into the other tube.
5. In each of the experiment, record the time taken for the reaction to take place.
6. Observe each metal as they react and take down notes – appearance…
Concentration:
1. Retrieve two pieces of Mg (Magnesium) and set it aside.
2. Transfer 10 mL of HCl ( 0.5 Mol ) into test tube Number one, with a pipette.
3. Drop the test tube into the test beaker where you just put 10 ml of HCL and begin to start your stopwatch and see chemical reactions take place.
4. Take note of the time where the Mg reacts to the HCL.
5. Record observations.
6. Transfer 10 ml of HCl ( 1.5 Mol ) that was in the other beaker by using another pipette into another test tube.
7. Repeat steps 4-5.
Results:
TEMPERATURE
Temperature for magnesium in cold water
TIME(seconds)
10 seconds : Magnesium is reacting well (pretty fast) with the water, there are bubbles produced along the magnesium.
43 seconds : No particular smell, the magnesium is still reacting well…
136 seconds : The reaction is starting to slow down, we can know this because there are less bubbles produced than before
203 seconds : The reaction is slower than before, there is a strange smell
372seconds
[6minutes, 12 seconds] : The magnesium breaks down and stops reacting.
Temperature for magnesium in hot water
TIME(seconds)
10 seconds : Magnesium reacts much faster than it did with the cold water.
56 seconds : There is a strange smell; the test turns a bit translucent (milky colour).
80 seconds : Reaction is still strong and fast, the strange smell is stronger
157 seconds
[2 minutes 33 seconds] : The reaction stops.
CONCENTRATION:
Concentration (1.5 HCL)
TIME( minutes + seconds )
30 seconds : The magnesium reacts with the HCL , there are lots of bubbles, the test tube temperature rise due to the reaction inside the test tube, perhaps gas is produced…
2minutes 20seconds : There is a weird smell, the test tube turns translucent (milky).Water vapor is produced around the test tube…
3 minutes 12seconds : The magnesium disappears, perhaps it had dissolved…
Concentration (0.5 HCL)
TIME(minutes, seconds)
30 seconds The magnesium reacts with the HCL, less bubbles produced than 1.5 HCL. But gas is produced
1 minute 47seconds : The test tube is hot, there is a smell, and little water vapor produced…
5minutes 55seconds : The reaction is still going on; however the reaction is weaker than at first…
SURFACE AREA:
Rolled piece of Mg
TIME(minutes, seconds)
24 seconds : Bubbles starting to form
1minute 5seconds : Amount of bubbles increase
8minutes 30 seconds : Bubbles starting to vanish
Unrolled piece of Mg
TIME(minutes, seconds)
24 seconds : Bubbles starting to form
1minute 5seconds : Amount of bubbles increase
9minutes 2seconds : Bubbles starting to vanish
Conclusion:
At the end of the experiment it was more than obvious that the three experiments affected the rates of reaction of the magnesium. First of all, for the Surface Area, when we placed the magnesium as a smaller area (rolled piece of Mg), the magnesium reacted faster than when it was as a bigger area (Unrolled piece of Mg). This is because there are more chances of particles colliding. Secondly, our clear results showed that the difference in temperature could change the rate of reaction in a big gap. When the magnesium was placed in the water with the higher temperature (hot) the reaction was much faster (almost by X3).This is because the higher the temperature the more active the particles get, so they tend to move faster, which means faster reaction. Last but not least, in our concentration experiment we investigated that the more concentrated a solution was the rate of reaction is faster. According to our results the HCL solution of 1.5 moles was 2 minutes 38 seconds faster than the HCL solution of 0.5 moles. This is giving the solutions more chances of collision. Overall, the three experiments (Surface Area, Concentration and the temperatures) affected the rate of reaction. The difference between the each experiment either cold or hot, bigger or smaller in surface, more or less concentrated gave a really big difference. Therefore the results showed us that there is a definite way from each of the experiment which had a faster rate of reaction which would be useful later when defining other experiments.
Sources of error:
1. The room temperature was not consistent and it could’ve altered results during the temperature test of the magnesium.
2. The size of magnesium could have been slightly different which could have affected the time that the magnesium took to react.
3. During the cold-water temperature experiment, the temperature might have been altered when the ice melted, thus changing the temperature. And when the instructor put more ice to keep it cold, then the temperature before would not be as equal.
4. The thermometer might have given a wrong indication during the cold-water temperature experiment.
5. We should have carried out the experiment in one time period, however due to the lack of time we divided the work of our experiment into 3days, which could have gave inaccurate temperature stability.
6. In the concentration experiment (HCL of 0.5) the magnesium didn’t stop reacting, therefore we had to finish the experiment at the 5th minute otherwise it was going to take too long. However this is not an accurate result.
7. Limited time. Due to the teacher’s ABSENCE we could not repeat the experiment to make it a fair experiment.
Science Post
Title
Stoichiometric relationship between the quantities of Pb(NO3)2, NaI, PbI2, and NaNO3 in a chemical reaction
1. Pb(NO3)2 + 2NaI PbI2 + 2NaNO3
2. and 3.
| Group Number | Mass Pb(NO3)2 | Mass
NaI |
Mass
PbI2 |
Moles Pb(NO3)2 | Moles NaI | Moles PbI2 | |
| 1 | 1.66g | 0.75g | 1.64g | 0.005 | 0.005 | 0.0036 | |
| 2 | 1.66g | 0.90g | 1.02g | 0.005 | 0.006 | 0.0022 | |
| 3 | 1.66g | 1.05g | 1.15g | 0.005 | 0.007 | 0.0025 | |
| 4 | 1.66g | 1.20g | 1.25g | 0.005 | 0.008 | 0.0027 | |
| 5 | 1.66g | 1.35g | 1.57g | 0.005 | 0.009 | 0.0034 | |
| 6 | 1.66g | 1.50g | 1.66g | 0.005 | 0.01 | 0.0036 | |
| 7 | 1.66g | 1.65g | 2.11g | 0.005 | 0.011 | 0.0046 | |
| 8 | 1.66g | 1.80g | 2.22g | 0.005 | 0.012 | 0.0048 | |
| 9 | 1.66g | 1.95g | 2.12g | 0.005 | 0.013 | 0.0046 | |
| 10 | 1.66g | 2.10g | 2.18g | 0.005 | 0.014 | 0.0047 | |
4.
5. The graph shows the relationship between the quantities of lead iodide (PbI2) produced according to the mass of sodium iodide (NaI) given. By observing the graph, we can see that starting from 0.006 to 0.0011 moles of sodium iodide, the quantity of moles of lead iodide is increasing from 0.0022 to 0.0046. On the other hand, we can also see that from 0.0011 to 0.0014 moles of sodium iodide, the line that represents the quantity of moles of lead iodide is fairly flat, in comparison to the escalating, steep line from 0.006 to 0.0011 moles of sodium iodide. The last 1/3 of the graph maintains a quite flat line because when the moles of sodium is present from 0.0011 moles onwards, sodium iodide’s role changes from the limiting reactant to the reactant that is present in excess and lead nitrate (Pb(NO3)2) becomes the limiting reactant. As it is lead nitrate that affects the amount of lead iodide produced in the last 1/3 of the experiment, the amount of lead iodide produced does not have a huge difference because the amount of lead nitrate present remains constant throughout the whole experiment, which is having a mass of 1.66g or moles of 0.005. In conclusion, when sodium iodide is present from 0.006 to 0.011 moles, sodium iodide is the limiting reactant, thus the quantity of moles of lead iodide increases from 0.0022 to 0.0046. When sodium iodide is present from 0.0014 moles, lead nitrate becomes the limiting reactant; hence the quantity of moles of lead iodide doesn’t change much because lead nitrate is present with the amount of 0.005 moles throughout the experiment.
6. (a) Pb(NO3)2 (lead nitrate) is the reactant that is present in excess.
(b) NaI (sodium iodide) is the limiting reactant.
Predicted mass of PbI2 using Pb(NO3)2
Calculations:
1.66/331.2074 = x/1 –> x = 1.66/331.2074 = 0.005 mol Pb(NO3)2
Since ratio is 1 to 1, the mol stays the same. (0.005 mol PbI2)
0.005/1 = x/461.008 –> x = 461.008 * 0.005 = 2.305 g
Predicted mass of PbI2 using NaI
Calculations:
If NaI = 0.75g, PbI2 = 1.153 g
If NaI = 1.35 g, PbI2 = 2.074 g
For group numbers 1-5, Pb(NO3)2 always produces 2.305g of PbI2 whilst NaI produces a range of 1.153g to 2.074g of PbI2. This shows that NaI will always produce less than PbI2 than Pb(NO3) 2, thus it is the limiting reactant.
7. (a) The NaI (sodium iodide) is the reactant that is present in excess.
(b) The Pb(NO3)2 (lead nitrate) is the limiting reactant.
Predicted mass of PbI2 using Pb(NO3)2
Calculations:
1.66/331.2074 = x/1 –> x = 1.66/331.2074 = 0.005 mol Pb(NO3)2
Since ratio is 1 to 1, the mol stays the same. (0.005 mol PbI2)
0.005/1 = x/461.008 –> x = 461.008 * 0.005 = 2.305 g
Predicted mass of PbI2 using NaI
Calculations:
If NaI = 1.65g, PbI2 = 2.536g
If NaI = 2.10g, PbI2 = 3.227g
For group numbers 7-10, Pb(NO3)2 always produces 2.305g of PbI2 whilst NaI produces a range of 2.536g to 3.227g of PbI2. This shows that NaI will always produce more PbI2 than Pb(NO3)2, thus it is the reactant that is present in excess.
8. The mole ratio of Pb(NO3)2 : NaI for group number 6 is 1 : 2. Because of the ratio, there is no limiting reactant for group number six. As the mole ratio of Pb(NO3)2 : NaI : PbI2 is 1 : 2 : 1, so the moles of PbI2 predicted will always be 0.005. As a result, the shape of the graph when NaI is 0.01 moles is affected equally by number of moles of NaI and Pb(NO3)2.
Palestine VS. Israel
AVo12 That's the way I like it... :) » ict10bertoia
Agreement:
- Israelis should provide the Palestinians more water. Although Israel agreed to such an undertaking, there is still a lack of respect for the Palestinians. Even though there is a big desert in Israel, that doesn’t mean that they can have three times more water than Palestine.
- Israel should satisfy the Palestinians’ immediate needs for water. Assuming 50mcm/year per Palestinian as the minimum requirement for domestic use, an additional allocation of 70mcm/year should be considered.
- Israel, Jordan and Palestine need to start on the construction of the West Ghor canal as agreed upon in the Johnston Plan.
- A new Peace preservation law should be established to stop the negotiations. So far, seems like Israel is still in the commanding position over Palestine.
- All countries that borders the Jordan River Basin should cooperate in forming a basin-wide regional authority
- Israelis and Palestinians should start working on clearing the heavily mined areas. Israel should lift the restrictions imposed on Palestinians to enable them to properly utilize their land and water resources, especially in the Jordan Valley.
- How will Israel still obtain the water that it needs to maintain a reasonable standard of living?
Israel should use less water from the aquifer. Israel should reduce the water usage for swimming pools, watering plants and etc… Even though people need swimming pools for pleasure and plants need water to survive, their usage of water is excessive. Human life is more precious than pleasure and plants’ survival. So Israelis should concentrate on using water that is necessary for their survival.
- How will Palestine obtain the water that it needs to maintain a reasonable standard of living?
Palestine should convince Israel to give them more water. Also, they should try to search for water from the nature. For example rain water harvest and digging wells.
Biology 10- Photosynthesis
MGuilhem12 Welcome to Wonderland ! » ict10bertoia
Photosynthesis
Leaves apparently look green; the color can be explained by the absorption of the pigment by the light. Chlorophyll absorbs primary color such as blue and red, and reflects green and yellow lights.
The electrons get excited by the energy of the light and travelled pass several molecules in the thylakoid membrane, we call this passage “Electron Transport Chains” (ETC).
Photophosphorylation: It’s the process of creating ATP from the energy of the sunlight. This process is mainly occurred in the thylakoid of a leaf.
This process that is taken place in the tylakoid can be divided into two parts:
Photosynthesis II:
_ The light (which contains proton) arrives on the reactions center of the pigment and causes the excitement of electrons. An excited electron will travel up to the storage (the electrons accepter).
The excited electron that leaves the pigment has to be replaced by another electron. The water molecule (H2O) is divided, and the chlorophyll will take an electron from the hydrogen atom for replacement. The hydrogen atom turns into an ion (H+).
_Then the excited electron passes through a membrane that contains protein. As the electron passes through this membrane, it looses its energy because the energy is used by the membrane to produce ions H+ into the thylakoid.
As the travel of the electron continues through the thylakoid membrane, more hydrogen will be produced. These hydrogen ions will have to evacuate through a carrier protein. As the passage of the hydrogen through the channel portion, this movement gives the energy to create ATP. A reaction will be made between a molecule of ADP and a phosphate group, which will give the creation of ATP (ADP + P = ATP).
Photosynthesis I:
_ The electron now arrives at the second pigment, the electrons has lost most of its energy through his previous passage. Once again the light hit on the reaction center of the pigment, the electron that arrived, replace the place of a new excited electron.
_ The excited electron travels up to the storage (the electron receptor) called NADP+. The excited electron + hydrogen ion + the electrons accepter create NADPH.
In conclusion, the absorption of light in the pigment and the excited electron through the ETC in the thylakoid membrane explain the influence of the sunlight on the color of the leaves.
Science:Lab Report on Convalent Ionic Compounds
QNguyen12 MinhQuang's Blog » ict10bertoia
Title
Experimenting Different Substances to Analyze Their Properties to Identify Ionic and Covalent Compounds
Problem
To determine whether the unknown compound is an ionic or covalent compound by analyzing its properties compared to the other substances.
Materials
4 spoons of sodium chloride
4 spoons of potassium
4 spoons of sucrose
4 spoons of benzoic acid
4 spoons of unknown compound
1 Bunsen burner
1 match
1 conductivity tester
1 Spark machine
1 scoop
1 spoon
1 250mL beaker
1 watch
Procedure
1. Light the Bunsen burner using the wooden splint or matches.
2. Use the scoop to get a small amount of sodium chloride.
3. Place the sodium chloride onto the spoon,
4. Place the spoon over the flame to melt the sodium chloride and begin timing.
5. Record the time when the sodium chloride begins to melt.
6. Repeat steps 2-5 using each of the other 4 compounds.
7. Repeat steps 2-6 again so that two trials have been done for each compound.
8. Extinguish the Bunsen burner once finished.
9. Determine the relative hardness of each substance by rubbing a small amount of it between your fingers.
10. Wash your hands immediately with lots of cold water each trial.
11. Record your observations.
12. Add a “scoop full” of each substance to tap water in the beaker.
13. Stir the mixture using the scoop or by swirling the beaker.
14. Record your observations.
15. Prepare the conductivity tester using the solutions you prepared in step 13.
16. Test each solution and record your observations.
Results
| Substance | Time used to melt substance | Relative hardness | Observations when mixing | |
| Trial 1 | Trial 2 | |||
| Sucrose | 25 seconds | 27 seconds | Like sand, neither very hard nor very soft, broke into smaller pieces when rubbed | Dissolved in 50 seconds |
| Benzoic acid | 25 seconds | 30 seconds | Very, very smooth, like powder | Does not dissolve, some of the substance sank to the bottom of the beaker |
| Potassium iodide | 5 minutes plus | 5 minutes plus | Texture almost like sucrose but melted in a few seconds while rubbing | Dissolved in 10 seconds |
| Sodium chloride | 5 minutes plus | 5 minutes plus | Smooth, softer than sucrose | Dissolved in 15 seconds |
| Unknown compound | 5 minutes plus | 5 minutes plus | Almost like flour but had a slippery touch | Dissolved in 15 seconds but becomes a color of milky white, although very sparse and some of it are floating around |
Conductivity Images
Figure 1 Sucrose
Figure 2 Benzoic Acid
Figure 3 Potassium Iodide
Figure 4 Sodium Chloride
Figure 5 Unknown Compound
| Substances | Conductivity range (µS/cm) | |
| Trial 1 | Trial 2 | |
| Sucrose | 525 – 700 | 200 |
| Benzoic Acid | 2300 – 3200 | 1800 – 2200 |
| Potassium Iodide | 10000 | 10000 |
| Sodium Chloride | 10000 | 10000 |
| Unknown Compound | 226 – 246 | 200 – 220 |
Conclusions
At the analysis questions, our hypothesis was that the unknown compound is a covalent compound. According to the data, the relative hardness of the unknown compound was relatively soft, almost like flour. In addition, unlike sucrose, an ionic compound, which felt like sand, a little hard and rough; the unknown compound had a slippery touch to it, like soap. Another property of covalent compounds that the unknown compound also has is that it is not very soluble with water. According to the observations during mixing the substance with tap water, most of it was dissolved in 15 seconds and those that didn’t dissolved was floating in the mixture. Other than that, by observing the conductivity range of the 5 substances in this experiment, the unknown compound has one of the lowest conductivity ranges, ranging from 200µS/cm to 246µS/cm, which fits the property of a covalent compound being a poor electrical conductor.
Sources of Error
1. Many students have been using the substances constantly during the experiments. The cover of the bottles of the substances have been opened and closed several times, thus the substances might be moistened over the course of the experiment. This may affect the results as the substances are closer to the state of liquid than solid if they were moistened. In addition, the substances would also seem relatively softer, thus affecting the observations, results and conclusions.
2. According to the procedures, we were supposed to use the scoop to get a small amount of substance to melt it. However, the exact amount needed is not specified. This may affect the results as the more of the substance was scooped to be melted, the time used to melt the substance is longer. For example, the unknown compound was predicted to be a covalent compound. However, it used more than 5 minutes to be melted, which seemed to fit the property of ionic compounds, not covalent compounds. If the amount of substances was stated specifically and we were able to measure with lab equipment, the results would be more accurate.
3. We used two different days to do the experiment. On the second day, although the scoop that we used to melt the substances has been washed, it was black with residue. This may affect the results of time used to melt the substances because the fire was not just heating the scoop to melt the substances, it was also heating the extra residue stuck on the spoon.
4. When we were melting the substances, the distance between the spoon and the fire is not constant, as we held the spoon with our hands, not with lab equipment. This may affect the time used for the substances to melt, because a shorter distance causes the substances to melt faster whilst a longer distance causes the substances to melt slower. If we used lab equipment to hold the spoons, our results may be more accurate.
5. Although our fingertips are one of the most sensitive body parts, but the sensitivity of everyone’s fingertips is different. Sometimes one may think that sucrose is relatively hard while the other may think that sucrose is relatively soft. If we were able to use to hardness testing machine, the results would be very accurate, instead of just observations that were written down according to our feelings.
- In Chemistry, we are learning the difference between ionic and covalent compounds. This experiment helps us find those properties of those compounds.
Experimenting Different Substances to Analyze Their Properties to Identify Ionic and Covalent Compounds
WTan12 Syn Pondering » ict10bertoia
Title
Experimenting Different Substances to Analyze Their Properties to Identify Ionic and Covalent Compounds
Problem
To determine whether the unknown compound is an ionic or covalent compound by analyzing its properties compared to the other substances.
Materials
4 spoons of sodium chloride
4 spoons of potassium
4 spoons of sucrose
4 spoons of benzoic acid
4 spoons of unknown compound
1 Bunsen burner
1 match
1 conductivity tester
1 Spark machine
1 scoop
1 spoon
1 250mL beaker
1 watch
Procedure
1. Light the Bunsen burner using the wooden splint or matches.
2. Use the scoop to get a small amount of sodium chloride.
3. Place the sodium chloride onto the spoon,
4. Place the spoon over the flame to melt the sodium chloride and begin timing.
5. Record the time when the sodium chloride begins to melt.
6. Repeat steps 2-5 using each of the other 4 compounds.
7. Repeat steps 2-6 again so that two trials have been done for each compound.
8. Extinguish the Bunsen burner once finished.
9. Determine the relative hardness of each substance by rubbing a small amount of it between your fingers.
10. Wash your hands immediately with lots of cold water each trial.
11. Record your observations.
12. Add a “scoop full” of each substance to tap water in the beaker.
13. Stir the mixture using the scoop or by swirling the beaker.
14. Record your observations.
15. Prepare the conductivity tester using the solutions you prepared in step 13.
16. Test each solution and record your observations.
Results
| Substance | Time used to melt substance | Relative hardness | Observations when mixing | |
| Trial 1 | Trial 2 | |||
| Sucrose | 25 seconds | 27 seconds | Like sand, neither very hard nor very soft, broke into smaller pieces when rubbed | Dissolved in 50 seconds |
| Benzoic acid | 25 seconds | 30 seconds | Very, very smooth, like powder | Does not dissolve, some of the substance sank to the bottom of the beaker |
| Potassium iodide | 5 minutes plus | 5 minutes plus | Texture almost like sucrose but melted in a few seconds while rubbing | Dissolved in 10 seconds |
| Sodium chloride | 5 minutes plus | 5 minutes plus | Smooth, softer than sucrose | Dissolved in 15 seconds |
| Unknown compound | 5 minutes plus | 5 minutes plus | Almost like flour but had a slippery touch | Dissolved in 15 seconds but becomes a color of milky white, although very sparse and some of it are floating around |
Conductivity Images
Figure 1 Sucrose
Figure 2 Benzoic Acid
Figure 3 Potassium Iodide
Figure 4 Sodium Chloride
Figure 5 Unknown Compound
| Substances | Conductivity range (µS/cm) | |
| Trial 1 | Trial 2 | |
| Sucrose | 525 – 700 | 200 |
| Benzoic Acid | 2300 – 3200 | 1800 – 2200 |
| Potassium Iodide | 10000 | 10000 |
| Sodium Chloride | 10000 | 10000 |
| Unknown Compound | 226 – 246 | 200 – 220 |
Conclusions
At the analysis questions, our hypothesis was that the unknown compound is a covalent compound. According to the data, the relative hardness of the unknown compound was relatively soft, almost like flour. In addition, unlike sucrose, an ionic compound, which felt like sand, a little hard and rough; the unknown compound had a slippery touch to it, like soap. Another property of covalent compounds that the unknown compound also has is that it is not very soluble with water. According to the observations during mixing the substance with tap water, most of it was dissolved in 15 seconds and those that didn’t dissolved was floating in the mixture. Other than that, by observing the conductivity range of the 5 substances in this experiment, the unknown compound has one of the lowest conductivity ranges, ranging from 200µS/cm to 246µS/cm, which fits the property of a covalent compound being a poor electrical conductor.
Sources of Error
1. Many students have been using the substances constantly during the experiments. The cover of the bottles of the substances have been opened and closed several times, thus the substances might be moistened over the course of the experiment. This may affect the results as the substances are closer to the state of liquid than solid if they were moistened. In addition, the substances would also seem relatively softer, thus affecting the observations, results and conclusions.
2. According to the procedures, we were supposed to use the scoop to get a small amount of substance to melt it. However, the exact amount needed is not specified. This may affect the results as the more of the substance was scooped to be melted, the time used to melt the substance is longer. For example, the unknown compound was predicted to be a covalent compound. However, it used more than 5 minutes to be melted, which seemed to fit the property of ionic compounds, not covalent compounds. If the amount of substances was stated specifically and we were able to measure with lab equipment, the results would be more accurate.
3. We used two different days to do the experiment. On the second day, although the scoop that we used to melt the substances has been washed, it was black with residue. This may affect the results of time used to melt the substances because the fire was not just heating the scoop to melt the substances, it was also heating the extra residue stuck on the spoon.
4. When we were melting the substances, the distance between the spoon and the fire is not constant, as we held the spoon with our hands, not with lab equipment. This may affect the time used for the substances to melt, because a shorter distance causes the substances to melt faster whilst a longer distance causes the substances to melt slower. If we used lab equipment to hold the spoons, our results may be more accurate.
5. Although our fingertips are one of the most sensitive body parts, but the sensitivity of everyone’s fingertips is different. Sometimes one may think that sucrose is relatively hard while the other may think that sucrose is relatively soft. If we were able to use to hardness testing machine, the results would be very accurate, instead of just observations that were written down according to our feelings.
