drates
Name: Anna Dais
Partner’s Name: Avery Anderson
Thursday 3:10-6pm 9/7/17
CHMY 141-218
TA: Mackenzie Lynes
Introduction The purpose of this lab was to explore the characteristics of hydrates. Hydrates are solid ionic compounds that contain water that is chemically bound to the crystal. In doing this lab, the percentage of water contained in various hydrates, if dehydration is a reversible or irreversible change, and the mathematical relationship between starting mass and mass lost. As there is no simple way to predict the amount of water molecules in a hydrated compound, it must be determined by experimenting. This experiment involves heating said hydrates so the water molecules evaporated from the solid compound. In the different
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While the sample is cooling, record any observations made in notebook. Once the crucible is cooled, record the mass of crucible and substance together. Repeat process with a different mass of beginning substance.
Part Three: Repeat the experiment from part one using Epsom salt. Record observations in notebook.
Observations and Data:
Part One:
Table 1:
Substance
Before Heat
During-After Heat
After Rehydration
Hydrated Copper Sulfate
Blue, powdery, grainy, crystal like
Became a darker blue, then turned to white, remained grainy, no longer crystal like.
After adding water, goes back to the original observed state
Hydrated Ferrous Sulfate
Greenish tan, grainy
Turned lighter tan. Looks dry and sand like
Turned milky brown
Hydrated Cobalt Sulfate
Fuchsia, large chunks/ crystals
Turned dark blue to light purple to baby blue powder consistency while expanding
Turned back to dark blue liquid, within a few minutes turned to solid and fuchsia
Sugar
White, Grainy, crystalized
Melted to a clear liquid, turned yellow to brown emitting strong sweet smell
Stayed melted, mixed in with the water added
Table 2:
Reversible
Irreversible
Hydrated copper sulfate
Hydrated cobalt sulfate
Sugar
Hydrated Ferrous Sulfate
Part Two:
Table 3:
Subject
Sample 1
Sample 2
Peer Sample 1
Peer Sample 2
Peer Sample 3
Crucible and sample before heat
27.48g
29.04g
29.92g
29.09g
30.098g
Crucible before heat
26.045g
26.045g
28.9g
27.65g
29.08g
Sample before heat
1.635g
2.995g
1.02g
1.44g
1.02g
The purpose of this lab is to determine the formula of an unknown hydrate. To achieve this, we heated a hydrate over a Bunsen burner to drive out the water. As a result, the anhydrate is left and the data is used to calculate the mole ratio between the amount of anhydride and water. Then the mole ratios are used to calculate the hydration number, which was 4.8, but was rounded to 5 in the formula. The accepted formula is 〖CuSO〗_4∙5H_2 O and the percent of error was 4%.
This experiment is based on determining the chemical formula for a hydrated compound containing copper, chloride, and water molecules in the crystal structure of the solid compound, using law of definite proportion. The general formula of the compound is CuxCly•zH2O, and aim is to determine chemical formula of this compound.
The purpose of this experiment was to determine the percent by mass in a hydrated salt, as well as to learn to handle laboratory apparatus without touching it. The hydrated salt, calcium carbonate, was heated with high temperature to release water molecules. Gravimetric analysis was used in this experiment to determine the percent by mass of water in a hydrated salt. The hypothesis of this experiment was accepted on the basis that the percent by mass of volatile water in the hydrated salt would be fewer than 30%. The percent by mass was determined by the mass of water loss devised by the mass of hydrated salt multiplied by total capacity
The mass of the water was found by subtracting the original mass of the hydrate by the anhydride, that was found after heating the hydrate and evaporating the water. However, if the hydrate was not fully heating and there was still excess water remaining, this excess water mass would be included in the anhydride mass. This would make the mass of the anhydride larger and the mass of the water smaller. If the mass of the water was smaller, then the amount of moles of water would also be smaller. The mole ratio of anhydride to water would be larger because the denominator in the ratio, water in this case, would be smaller, so the entire ratio would essentially increase. This would mean that the number of molecules of water would be smaller as a result.
The percent of water can be determined in a hydrate by first determining the mass of the hydrate Copper (II) Sulfate penta-hydrate. The substance will be a deep blue color when it is a hydrate. By heating the substance, water is evaporated, removing the water from the hydrate, making it anyhydrous through a simple decomposition reaction. Evaporation is completed when the substance turns from a blue to a white/ grey color. The mass of the water in a hydrate is determined by subtracting the mass of the hydrate from the mass of the anhydrate. The mass of the water is then divided by the mass of the hydrate, and multiplied by one hundred, resulting in the percent of water in the hydrate, which is 36.35%. The percent error is determined by subtracting
When the red Co(NO3)2*6H2O crystal was added to the white NH4 crystal, and water was added to dissolve, the solution turned blue in color. As the solution was nixed, the color changed to that of a blue-purple and a blue precipitate formed. When the 6 M NH3 began to be added, the color shifted to dark purple color after 15 mL of ammonia and the amount of the precipitate was less. After 20 mL of ammonia, the solution became a red brown with very little of the blue precipitate. After 30 mL of ammonia, the solution was similar in color to an iodine solution, a dark brown-red, almost black in color. At this point there was no visible precipitate on the surface of the solution. After 40 mL of the ammonia had been added, the solution was the same iodine like color as before. When closely examined, there was a black precipitate that had settled on the bottom of the beaker. At this point, hydrogen peroxide, 3% H2O2, was added to solution. After 4 mL of the H2O2 was added, the solution was the same color and the precipitate had not changes. After 8 mL of the H2O2, there was not noticeable change. After 12 mL of the H2O2, the solution was slightly redder in color but the precipitate had not changed. After 15 mL of H2O2, the solution was the same color and no changes had occurred to the precipitate. At 17 mL, the solution began to effervesce slightly, though there
Medium amount of precipitate became present; solution then became opaque and turned medium blue in
The mass percent of water was determined using the mass of water and dividing it by the total mass of the hydrate and then multiplying that answer by 100%. The number of moles of water in a hydrate was determined by taking the mass of the water released and dividing it by the molar mass of water. The number of moles of water and the number of moles of the hydrate was used to calculate the ratio of moles of water to moles of the sample. This ratio was then used to write the new and balanced equation of the dehydration process. The sample was then rehydrated to the original state and the percent of the hydrate recovered was calculated by using the mass of the rehydrated sample by
The purpose of this lab is to determine the percent of water in a hydrate. I learned that copper sulfate hydrate is blue on its own but, when heat is added it will change color to a dim gray. One error that may have occurred is the failure to zero the scale which would ultimately change the math in the equation. Another error that may occur in this lab is forgetting to wait the recommended amount of cooling time, which would change the mass of the elements. At the end if the lab when we look to the questions, it is also beneficial to look at the notes for the lab because it helps with the setup of equations that may come with the questions, also it is very helpful
The goal of this experiment was to determine the empirical formula for a hydrate of magnesium sulfate and water. The technique that was used was measure the mass of the hydrate and then apply heat to evaporate the water. Then determine the mass of water that was in the hydrate and the mass of the remaining magnesium sulfate. The equation for the hydrate is determined by calculating the mole to mole ratio of the water and the anhydrous. The resulting formula will be formated as: MgSO4*_H2O
The powdered cobalt oxalate hydrate was weighed to about 0.3 g and placed in a pre-weighed crucible. The crucible and the cobalt oxalate were then heated until the cobalt oxalate decomposed into a stable, black solid, or Co3O4. Once the crucible was sufficiently
Many studies related to gas hydrate occurrences worldwide has been reported mainly to better characterize reservoirs, theirs potential as energy resource and the role gas hydrate can play in global climate change (Kennett et al. 2003; Milkov, 2004). Concerning the former, large amounts of methane gas can be trapped in form of gas hydrate (Milkov, 2004), being considered as an important greenhouse gas. It is estimated that over a 20-year period, one ton of methane has a global warming potential 84 to 87 times greater than carbon dioxide and over a century, this warming potential is 28 to 36 times greater according to the Intergovernmental Panel on Climate Change (IPCC, 2014). For these reasons in the last decades several projects have been carried out to assess the global methane hydrate quantities. The estimation of the global methane reservoir have decreased while the knowledge about hydrate reservoirs have increased; in fact Kvenvolden (2000) estimated 11 000 Gt of carbon in hydrate, while the last estimation ranges from 500 to 2 500 Gt of natural carbon (Milkov, 2004). Despite this decreasing, gas hydrate reservors still play an important role in the global carbon cycle.
In this experiment, it is evident that the measurements of the temperatures are consistent with physical change presented in each the solution. The initial temperature of the water was 22 degrees due to room temperature. Through this, it is identifiable on which solution liberates heat (exothermic) or absorbs heat (endothermic), by comparing with the water in room temperature. Sodium Hydroxide: Sodium Hydroxide is recognised as exothermic solution. Due to the lattice energy and hydration energy of 737 kJ/mol and 779kJ/mol has a change of -41kJ/mol while comparing to a solution which has Lattice Energy of 779 kJ/mol and a Hydration Energy of 774 kJ/mol which has a change of +5kJ/mol, it is evident that energy need to separate the ions in sodium hydroxide allowing
Then, wait to see if the mg ribbon has turned to white ash. If it has turned to white ash, let the crucible cool and add 10 drops of distilled water. Then partially cover the crucible and heat for 10 min and then let it cool. Then after the crucible has cooled, weigh the mass of the crucible, lid, and mg ribbon inside. If the student had extra time he could reheat the crucible for 5-10 min and then let it cool down and weigh it
Heat the crucible on a slow blue flame for 2 min then 10 min on the hot flame.