Hydrate Lab Report

Investigation 3 Student ID E12008926 Evguenia Kelley
Section1
The purpose of the lab is to identify the compound based on a constant composition by performing a serious of tests. The hydrate is solid crystals compound and appears to be dry: since an ionic compound (salt) is crystallized from an aqueous solution (water), by heating the hydrate the water is released from ionic structure; therefore it is possible to measure the weight of the ionic compound and calculate its ratio to the liquid in the hydrate. The goal of the lab is to establish the identity of a given hydrate (“wet salt”) by comparing the results with known hydrate percentages.
Hydrates are ionic compounds (salts) that have a definite amount of
water as part of their structure. This “water of hydration” is released as vapor when the hydrate is heated. The remaining solid is known as the anhydrous salt. The general reaction for heating a hydrate is:

The Δ sign means that heat is applied. The percent of water in a hydrate can be found experimentally by accurately determining the mass of the hydrate and the mass of the anhydrous salt. The difference in mass is due to the water lost by the hydrate. The percent of water in the original hydrate can then be calculated using a version of the percent composition formula:

Average Value of Salt in Hydrate = (Salt%1+Salt%2)/2
Average Value of Water in Hydrate = (Water%1+Water%2)/2
Section 2 1. Mass Measurements:
The given hydrate was placed in a beaker and weighted by the scale (The scale was zeroed out with the beaker, before the hydrate was placed inside). The result was recorded in a table (0.605g). The procedure was repeated for accurate results. The result was recorded in a table (0.990g) 2. Heating Process:
The Buncen burner was used in the heating procedure.
The burner was turned on and the flame came out from the top part. The beaker filled with the weighted hydrate inside, was held over the open flame for few minutes. Visible vapor came out from the beaker, when parts of water were evaporated out of the hydrate. The color of the compound has changed from bright blue to white. After letting the beaker cool down, it was placed on the scale (The scale was initially zeroed out with the beaker, before the hydrate was placed inside) and the new result was recorded in a table (0.498g). The procedure of heating the hydrate in a beaker over an open flame was repeated three more times and the weighting procedure was repeated, the new results were recorded in a table (0.478g, 0.474g, 0.460g) Finally, when the last two measuring weight results were equal (0.460g=0.460g), the decision was made that all the liquid was evaporated from the compound. The procedure was repeated second time for more accurate results. The results were recorded in a table (0.615g, 0.584g, 0.572g, 0.566g) and
(0.566g=0.566g)
Calculations:
The recorded final weights of the salt (0.460g and 0.566g) were divided by recorded initial weights of the hydrate (0.605g and 0.990g) and then multiplied by 100 to calculate the percent of the water in the initial compound.
Since the procedure was repeated twice the final values (76% and 57%) were added and divided by 2 to calculate the average percent values.

Section 3 | Experiment1 | Experiment2 | Hydrate initial value | 0.605g | 0.990g | 1st weight | 0.498g | 0.615g | 2nd weight | 0.478g | 0.584g | 3rd weight | 0.474g | 0.572g | 4th weight | 0.460g | 0.566g |

%Anhydrous Salt in Hydrate (Experiment 1) | %Water in Hydrate (Experiment 1) | %Anhydrous Salt in Hydrate (Experiment 2) | %Water in Hydrate (Experiment 2) | (0.460g/0.605g)*100=76% | 100%-76%=24% | (0.990g/0.566g)*100=57% | 100%-57%=43% |

Average Value of Salt in a Hydrate | (76%+57%)/2=66.5% | Average Value of Water in Hydrate | (24%+43%)/2=33.5% |

Result of the lab was: The given hydrate is CuSO4 5H2O (Copper II Sulfate Pentahydrate)
The calculated value percentage of the Salt in hydrate (66.5%) and Water in hydrate (33.5%), suggests that the given initial compound is CuSO4
5H2O.