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Ch.3 - Molecules, Compounds & Chemical Equations
Tro - Chemistry: A Molecular Approach 4th Edition
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831당신이 사용하는 게 아니라요?교과서 변경
3장, 문제 133

Epsom salts is a hydrated ionic compound with the following formula: MgSO4 • x H2O. A 4.93-g sample of Epsom salts is heated to drive off the water of hydration. The mass of the sample after complete dehydration is 2.41 g. Find the number of waters of hydration (x) in Epsom salts.

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Step 1: Calculate the mass of the water driven off during the heating process. This can be done by subtracting the mass of the dehydrated sample from the original mass of the sample.
Step 2: Convert the mass of the water and the dehydrated sample (MgSO4) to moles. The molar mass of water (H2O) is approximately 18.015 g/mol and the molar mass of MgSO4 is approximately 120.37 g/mol.
Step 3: Divide the number of moles of water by the number of moles of MgSO4. This will give you the ratio of moles of water to moles of MgSO4, which is the value of x in the formula MgSO4 # x H2O.
Step 4: If the ratio is not a whole number, it may need to be rounded to the nearest whole number, as the number of waters of hydration (x) in a compound is typically a whole number.
Step 5: The value of x obtained is the number of waters of hydration in Epsom salts.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Hydrated Ionic Compounds

Hydrated ionic compounds, like Epsom salts (MgSO4·xH2O), consist of ionic species combined with water molecules. The 'x' in the formula represents the number of water molecules associated with each formula unit of the ionic compound. Understanding this concept is crucial for determining the amount of water lost during dehydration and calculating the value of 'x'.
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가이드 코스
02:04
Ionic Hydrates Naming

Mass Loss and Stoichiometry

Stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction. In this case, the mass loss during the heating of Epsom salts indicates the amount of water that was present. By applying stoichiometric principles, one can relate the initial mass of the hydrated compound to the mass of the dehydrated compound to find the number of water molecules.
추천 영상:
가이드 코스
01:16
Stoichiometry Concept

Molar Mass Calculation

Calculating molar mass is essential for converting between grams and moles of a substance. To find 'x', one must first determine the molar mass of both the hydrated and dehydrated forms of Epsom salts. This calculation allows for the determination of the number of moles of water lost, which directly correlates to the value of 'x' in the hydrated formula.
추천 영상:
가이드 코스
03:12
Molar Mass Calculation Example
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