Epsom salt is commonly purchased in the pharmacy for a variety of uses, anti-inflammatory, laxative, and cosmetic. epsom salt is a hydrated salt of magnesium sulfate. if 2.000 g of epsom salt are heated to remove the waters of hydration, 0.977 g of the anhydrous (without water) magnesium sulfate, mgso4, were obtained. calculate the number of waters of hydration, and write the chemical formula of the epsom salt.

Question

Chemistry

Elisa Lowery

2 May, 11:55

Epsom salt is commonly purchased in the pharmacy for a variety of uses, anti-inflammatory, laxative, and cosmetic. epsom salt is a hydrated salt of magnesium sulfate. if 2.000 g of epsom salt are heated to remove the waters of hydration, 0.977 g of the anhydrous (without water) magnesium sulfate, mgso4, were obtained. calculate the number of waters of hydration, and write the chemical formula of the epsom salt.

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Answers (1)

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Jaslene Zhang · Answer 1

Epsom salt is MgSO4.

We assume x water of hydration in the crystalline form.

Molecular mass of MgSO4 = 24+32+4*16=120

Molecular mass of MgSO4. xH2O = 120+18x

By proportion,

2.000/0.977 = (120+18x) / 120

Cross multiply

0.977 (120+18x) = 120*2.000

from which we solve for x

17.586x+117.24 = 240

x=122.78/17.586

=6.980

Answer: there are 7 water of hydration in Epsom salt, according to the experiment.

Note: more accurate (proper) results may be obtained by using exact values (3-4 significant figures) in the molecular masses. However, since water of hydration is the nearest integer, using approximate values (to at least two significant figures) suffice.