# Hydrate Lab Report for Chemistry Lab

Topics: Mathematics, Mole, Percent difference Pages: 4 (823 words) Published: November 19, 2013
9-19-13
Dehydrating and Rehydrating a Hydrate
Introduction
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 mass of the original hydrate and then multiplied by 100%. Data Presentation & Analysis

Table 1: The data was collected from the lab experiment. Sample calculations are shown. Mass of beaker with sample
30.765g
Mass of empty beaker
30.263g
Mass of sample
.502g
Mass of beaker with sample after 1st heat
30.661g
Mass of beaker with sample after 2nd heat
30.657g
Heating mass difference
.004g
Mass of anhydrate
.394g
Mass of H2O
.108g
Molar mass of CuCl2
135.0g/mol
Molar mass of H2O
18.0g/mol
Moles of anhydrous sample
2.92x10-3 moles CuCl2
Moles of H2O released
6.00x10-3 moles of H2O
Mass % of H2O
21.5% of H2O
% Absolute error
0% absolute error
Mass of rehydrated sample
.469g
% of hydrate recovered
93.4% CuCl2 H2O
The samples were placed in a desiccator instead of being left to cool on the lab bench between each heating. This is because the beaker and contents would cause the mass of fluctuate when placed on the tared balance if not cooled in the desiccator. This is used to store the beakers and the anhydrate so that the anhydrate does not absorb moisture from the air. The sample needed to return to the oven for a second heating to insure that all of the water was heated off of the sample. If...