Question

Please provide correct work & answers to the following, thank you!!

.A student observed that when heated his sample produced condensation on the upper walls of his test tube and changed color. When the sample was added to water it produce a solution with a color very similar to that of the original salt. Explain these observations 2. A student gets a measurement of 30.112 grams when he weighs a dry empty crucible and cover. He then adds an unknown hydrate of magnesium sulfate and gets a mass of 32.752 grams for the crucible, cover, and sample. After he heats the crucible to drive off the water of hydration and then cools it he finds the mass of crucible, cover, and contents to be 31.320 grams. a. What is the mass of the hydrate sample? of the anhydrate? b. What is the mass c. What is the mass of water driven off? d. How many moles of magnesium sulfate are there in the sample? e. How many moles of water are there in the hydrate? f. What is the formula of the hydrate?

Answer 1

a) Calculate the mass of the hydrate:

m hydrate = m total - m crucible = 32.752 - 30.112 = 2.64 g

b) m anhydrous = m total dry - m crucible = 31.320 - 30.112 = 1.208 g

c) m water = m hydrate - m anhydrous = 2.64 - 1.208 = 1.432 g

d) The moles are calculated:

n = g / MM = 1,208 g / 120.4 g / mol = 0.010 mol

e) n = 1432 g / 18 g / mol = 0.080 mol

f) The molar ratio is calculated by dividing the moles by the smallest number:

MgSO4: 0.01 / 0.01 = 1

H2O: 0.08 / 0.01 = 8

MgSO4.8H2O.

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