The vapor pressure of water at 100.0ºC is 0.720 atm. Determine the mass percent of iron (II) chloride, FeCl 2 , needed to reduce its vapor pressure to 0.655 atm. (MW of FeCl 2 is 126.756 g/mol)

The vapor pressure of water at a 100 degrees Celsius is 0.720 atmospheres. Determine the mass percent of iron 2 chloride needed to reduce its vapor pressure to 0.655 atmospheres. Here, we're given the molecular weight of iron 2 chloride as 126 0.756 grams per mole. Alright. So we need to determine the mass percent of iron 2 chloride. Here, since we're dealing with vapor pressure, we say pressure of our solution equals mole fraction of our solvent times the pressure of our pure solvent. Here, pressure of our solution, remember, is always lower because adding solute decreases my vapor pressure. And then this is x solvent, and then pressure of my pure solvent is 0.720 atmospheres. Divide both sides now by 0.720 atmospheres, and we'll have the mole fraction of my solvent. So mole fraction of solvent equals 0.9097. And that's the majority of the information given to us, but we need to realize here is that this piece of information is saying a lot, we just have to expand it out. Remember, mole fraction of my solvent, so we're going to have it up here to help us remember, is our moles of solvent divided by I times my moles of solute plus my moles of solvent. So if I were to expand this out, what it's really telling me is I have 0.9097 moles of solvent, so moles of water, divided by 1 mole of solution, because remember, mole fraction also means moles of of, in this case, a solvent divided by the total moles of solution. From this one mole of solution, we can expand it into 0.9097 moles of water divided by still 0.9097 moles of water. Remember we need I. Iron 2 chloride is ionic, it breaks up into 1 iron 2 ion plus 2 chloride ions. So that's 3 total ions. So here I is 3, and we don't know what the moles of iron 2chloride is, so that's x. Now guess what? We know that the total value on the bottom for mole fraction is equal to 1, so that means that this equals 1 because they're the same bottom. I just expanded it outwards. So make them equal to each other and help us to solve for x. So 3 x+.9097 equals 1. Subtract 0.9097 from both sides. So 3 x equals 0.0903. Divide both sides by 3. So x here, which equals my moles of iron 2 chloride, is 0.0301. So guess what? We have the moles of iron 2 chloride, and we have the moles of water. With this information, I can find the mass percent of iron 2 chloride. So mass percent equals the grams of iron 2. Alright? So here I would just change these moles, so 1 mole of iron 2 chloride on the bottom, and we're told the mass is 126.756 grams. When we work that out, that comes out to 3.8154 grams of iron 2 chloride, and then for mass percent, we need the grams of solution on the bottom, which would be the grams of our solute again, plus the grams of our solvent. Water is 0.9097 moles. So let's change that into grams. So here, remember, for water, 1 mole of water is 18.016 grams. Moles cancel out and we have here 16.3892 grams of water, and then we multiply this by 100. Doing that gives me my mass percent which would come out to 18 0.9%, which would give me option b as my correct answer. So just realize that although not a lot of information is given to us within this question, it does help us find the moles of our solvent. Just from that piece of information, I can expand it outwards and from it I can determine the moles of both my solvent water and my solute of iron 2 chloride. Once you know their moles, change them into grams, and you can find the mass percent of iron chloride.

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1. Matter and Measurements4h 29m

What is Chemistry?
7m

The Scientific Method
9m

Classification of Matter
16m

States of Matter
8m

Physical & Chemical Changes
19m

Chemical Properties
8m

Physical Properties
5m

Intensive vs. Extensive Properties
13m

Temperature (Simplified)
9m

Scientific Notation
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SI Units (Simplified)
5m

Metric Prefixes
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15m

Dimensional Analysis
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The Atom (Simplified)
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Wavelength and Frequency (Simplified)
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Electromagnetic Spectrum (Simplified)
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Electronic Structure
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Electronic Structure: Orbitals
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Valence Electrons of Elements (Simplified)
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Types of Chemical Reactions
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Spontaneous Redox Reactions
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Nature of Energy
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Solutions
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Introduction to Organic Chemistry
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The Alkyl Groups
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Intro to Hydrocarbons
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Isomers
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Chirality
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Intro to Addition Reactions
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Hydrogenation Reaction
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Hydrohalogenation Reaction
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Hydration Reaction
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Naming Benzene
19m

Benzene Reactions
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16m

Naming Ethers
13m

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6m

Alcohol Reactions: Dehydration Reactions
9m

Intro to Redox Reactions
8m

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7m

Reactions of Thiols
4m

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12m

Naming Aldehydes
12m

Tollens' and Benedict's Test
12m

Reduction of Aldehydes and Ketones
11m

Hemiacetal and Acetal Formation
11m

16. Carboxylic Acids and Their Derivatives1h 11m

Naming Carboxylic Acids
16m

Naming Esters
15m

Naming Amides
10m

Carboxylic Acid Reactions
4m

Ester Reactions: Esterification
4m

Ester Reactions: Acid-Catalyzed Hydrolysis
3m

Ester Reactions: Saponification
3m

Amide Formation
4m

Amide Hydrolysis
8m

17. Amines39m

Classifying Amines
3m

Naming Amines
12m

Naming Ammonium Salts
10m

Functional Group Priorities
8m

Amine Reactions
4m

18. Amino Acids and Proteins1h 51m

Intro to Amino Acids
6m

Amino Acid Three Letter Codes
5m

Amino Acid One Letter Codes
14m

Amino Acid Classifications
21m

Peptides
12m

Primary Protein Structure
4m

Secondary Protein Structure
17m

Tertiary Protein Structure
11m

Quaternary Protein Structure
10m

Summary of Protein Structure
7m

19. Enzymes1h 37m

Intro to Enzymes
3m

Enzyme Classification
34m

Enzyme-Substrate Complex
6m

Models of Enzyme Action
5m

Factors Affecting Enzyme Activity
12m

Enzyme Inhibition
8m

Enzyme Regulation: Allosteric Control
5m

Enzyme Regulation: Feedback Control
6m

Enzyme Regulation: Covalent Modification
14m

20. Carbohydrates1h 41m

Intro to Carbohydrates
4m

Classification of Carbohydrates
4m

Fischer Projections
4m

Enantiomers vs Diastereomers
7m

D vs L Enantiomers
9m

Cyclic Hemiacetals
8m

Intro to Haworth Projections
4m

Cyclic Structures of Monosaccharides
11m

Mutarotation
4m

Reduction of Monosaccharides
10m

Oxidation of Monosaccharides
7m

Glycosidic Linkage
14m

Disaccharides
7m

Polysaccharides
2m

21. The Generation of Biochemical Energy2h 8m

Intro to Metabolism
10m

ATP and Energy
12m

Intro to Cofactors
4m

Intro to Coenzymes
3m

Coenzymes in Metabolism
15m

Energy Production In Biochemical Pathways
5m

Intro to Citric Acid Cycle
6m

The Citric Acid Cycle
44m

Electron Transport Chain
13m

Oxidative Phosphorylation
7m

Aerobic Respiration Summary
5m

22. Carbohydrate Metabolism2h 22m

Intro to Carbohydrate Metabolism
5m

Intro to Glycolysis
8m

Glycolysis
28m

Glycolysis Summary
27m

Pyruvate Oxidation
3m

Anaerobic Respiration
16m

Total Energy from Glucose
10m

Intro to Gluconeogenesis
4m

Gluconeogenesis
37m

23. Lipids2h 26m

Intro to Lipids
6m

Fatty Acids
25m

Physical Properties of Fatty Acids
6m

Waxes
4m

Triacylglycerols
12m

Triacylglycerol Reactions: Hydrogenation
8m

Triacylglycerol Reactions: Hydrolysis
13m

Triacylglycerol Reactions: Oxidation
7m

Glycerophospholipids
15m

Sphingomyelins
13m

Steroids
15m

Cell Membranes
7m

Membrane Transport
10m

24. Lipid Metabolism1h 45m

Intro to Lipid Digestion
5m

Digestion of Lipids
6m

Lipoproteins for Transport
6m

Glycerol Metabolism
14m

Intro to Fatty Acid Oxidation
9m

Oxidation of Fatty Acids
21m

Total Energy from Fatty Acids
14m

Ketone Bodies
14m

Summary of Lipid Metabolism
12m

25. Protein and Amino Acid Metabolism1h 37m

Digestion of Proteins
5m

Intro to Amino Acid Catabolism
3m

Amino Acid Catabolism: Amino Group
14m

Amino Acid Catabolism: Carbon Atoms
20m

Intro to Urea Cycle
6m

The Urea Cycle
31m

Review of Metabolism
16m

26. Nucleic Acids and Protein Synthesis2h 54m

Intro to Nucleic Acids
4m

Nitrogenous Bases
16m

Nucleoside and Nucleotide Formation
9m

Naming Nucleosides and Nucleotides
13m

Phosphodiester Bond Formation
7m

Primary Structure of Nucleic Acids
11m

Base Pairing
10m

DNA Double Helix
6m

Intro to DNA Replication
20m

Steps of DNA Replication
11m

Types of RNA
10m

Overview of Protein Synthesis
4m

Transcription: mRNA Synthesis
9m

Processing of pre-mRNA
5m

The Genetic Code
6m

Introduction to Translation
7m

Translation: Protein Synthesis
18m

9. Solutions

Vapor Pressure Lowering (Raoult's Law)

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9. Solutions

Vapor Pressure Lowering (Raoult's Law)

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Multiple Choice

The vapor pressure of water at 100.0ºC is 0.720 atm. Determine the mass percent of iron (II) chloride, FeCl₂, needed to reduce its vapor pressure to 0.655 atm. (MW of FeCl₂ is 126.756 g/mol)

67.7%

18.9%

22.5%

58.3%

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The vapor pressure of water at 100.0ºC is 0.720 atm. Determine the mass percent of iron (II) chloride, FeCl2, needed to reduce its vapor pressure to 0.655 atm. (MW of FeCl2 is 126.756 g/mol)

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Vapor Pressure Lowering (Raoult's Law) practice set

The vapor pressure of water at 100.0ºC is 0.720 atm. Determine the mass percent of iron (II) chloride, FeCl₂, needed to reduce its vapor pressure to 0.655 atm. (MW of FeCl₂ is 126.756 g/mol)