14. Solutions

Molality

Molarity, Molality, Volume & Mass Percent, Mole Fraction & Density - Solution Concentration Problems

Water & Solutions - for Dirty Laundry: Crash Course Chemistry #7

Acetonitrile 1CH3CN2 is a polar organic solvent that
dissolves a wide range of solutes, including many salts.
The density of a 1.80 M LiBr solution in acetonitrile is
0.826 g>cm3. Calculate the concentration of the solution
in (a) molality,

Addition of 50.00 mL of 2.238 m H2SO4 1solution density
= 1.1243 g>mL2 to 50.00 mL of 2.238 M BaCl2 gives a white precipitate.
(b) If you filter the mixture and add more H2SO4 solution to the filtrate, would you obtain more precipitate? Explain.

What is the molality of the 40.0 mass % ethylene glycol 1C2H6O22 solution used for automobile antifreeze?

How to Calculate Molality

What's the Difference Between Molarity and Molality?

The density of acetonitrile 1CH3CN2 is 0.786 g>mL and
the density of methanol 1CH3OH2 is 0.791 g>mL. A solution is made by dissolving 22.5 mL of CH3OH in 98.7 mL of
CH3CN. (b) What is the molality of the solution?

Calculate the number of moles of solute present in each
of the following aqueous solutions: (b) 86.4 g of 0.180 m KCl,

Molality Concept 1

A solution is prepared by dissolving 20.2 mL of methanol
(CH3OH) in 100.0 mL of water at 25 °C. The final volume of the
solution is 118 mL. The densities of methanol and water at this
temperature are 0.782 g>mL and 1.00 g>mL, respectively. For
this solution, calculate the concentration in each unit.
b. molality

Describe how to prepare each solution from the dry solute and the solvent.
b. 125 g of 0.100 m NaNO3

Describe how you would prepare each of the following
aqueous solutions, starting with solid KBr:
(b) 125 g of 0.180 m KBr,

An aqueous NaCl solution is made using 112 g of NaCl diluted
to a total solution volume of 1.00 L. Calculate the molality of the solution. (Assume a density of
1.08 g>mL for the solution.)

Osmolality or Ionic Molality, represents number of dissolved particles in a solution.

Molality and Colligative Properties

Ethylene glycol, C2H6O2, is a colorless liquid used as auto-mobile antifreeze. If the density at 20 °C of a 4.028 m solu- tion of ethylene glycol in water is 1.0241 g/mL, what is the molarity of the solution? The molar mass of ethylene glycol is 62.07 g/mol

Molality Concept 2

Molality Example 1

A 0.944 M solution of glucose, C6H12O6, in water has a density of 1.0624 g/mL at 20 °C. What is the concentration of this solution in the following units?(c) Molality

Brass is a substitutional alloy consisting of a solution of
copper and zinc. A particular sample of red brass consisting of 80.0 % Cu and 20.0 % Zn by mass has a density of
8750 kg>m3. (a) What is the molality of Zn in the solid
solution?

Nalorphine 1C19H21NO3 2, a relative of morphine, is used to combat withdrawal symptoms in narcotics users. How many grams of a 1.3 * 10-3 m aqueous solution of nalor-phine are needed to obtain a dose of 1.5 mg?

Fluorocarbons (compounds that contain both carbon
and fluorine) were, until recently, used as refrigerants.
The compounds listed in the following table are all gases
at 25 °C, and their solubilities in water at 25 °C and 1
atm fluorocarbon pressure are given as mass percentages.
(a) For each fluorocarbon, calculate the molality of a saturated solution. 
Fluorocarbon Solubility (mass %)
CF4 0.0015
CClF3 0.009
CCl2F2 0.028
CHClF2 0.30

Molality Example 2

There’s actually much more in seawater than just dissolved NaCl. Major ions present include 19,000 ppm Cl-, 10,500 ppm Na+, 2650 ppm SO 2-, 1350 ppm Mg2+, 400 ppm Ca2+, 380 ppm K+, 140 ppm HCO3-, and 65 ppm Br-.
(a) What is the total molality of all ions present in seawater?

What's the Point of Molality?!?

Molarity vs. molality | Lab values and concentrations | Health & Medicine | Khan Academy

The density of a 15.7 M methanol (CH3OH) solution is 0.858 g/mL. If H2O is the solvent, what is the molality of the solution?

What is the ionic molality of sodium ions in a solution of 25.7 g NaNO3 dissolved in enough water to make a 150.0 mL of solution? Density of the solution is 1.02 g/mL.

 The mass must be converted to moles and the volume to liters. 

 Convert the mass to moles and divide by the volume in liters. 

 The volume of the solution must be in liters. 

 Molarity is defined as moles of solute divided by the liters of solution. 

 What is the molarity of a solution prepared by dissolving 5.00 g of NaCl in 500.0 mL of water? 

An aqueous KNO3 solution is made using 72.5 g of KNO3 diluted
to a total solution volume of 2.00 L. Calculate the molality of the solution. (Assume a density of
1.05 g>mL for the solution.)

Ascorbic acid 1vitamin C, C6H8O62 is a water-soluble vitamin. A solution containing 80.5 g of ascorbic acid dissolved
in 210 g of water has a density of 1.22 g>mL at 55 °C. Calculate
(c) the molality,

A solution is prepared by dissolving 43.0 g potassium chlorate, KClO3, in enough water to make 100.0 mL of solution. If the density of the solution is 1.760 g/mL, what is the molality of KClO3 in the solution?

The figure shows two identical volumetric flasks containing
the same solution at two temperatures.
(b) Does the molality of the solution change with the
change in temperature? [Section 13.4]
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/8b790225cfb31d32-1666019546940.jpg" alt="" />

The density of toluene 1C7H82 is 0.867 g>mL, and the density of thiophene 1C4H4S2 is 1.065 g>mL. A solution is made
by dissolving 8.10 g of thiophene in 250.0 mL of toluene.
(b) Calculate the molality of thiophene in the solution.

A solution is made containing 20.8 g of phenol 1C6H5OH2
in 425 g of ethanol 1CH3CH2OH2. Calculate
(c) the molality of phenol.

 48.0% by mass is equivalent to 48.0 g solute per 100 grams of solution.  Convert grams of solute to moles and mass of the solution to kilograms 

 The mass of the solution must be expressed in kilograms. 

 48.0% by mass is equivalent to 48.0 g solute per 100 grams of solution.  Convert g solute to moles and mass of the solution to kilograms 

 Molality is defined as moles of solute divided by kg of solvent. 

Calculate the molality of an aqueous solution that is 48.0% by mass Ca(NO3)2.

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15. Chemical Kinetics

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[BOOK CHEM] Clutch Version

Types of Aqueous Solutions

When an ionic solid dissolves, ions leave the solid and become dispersed in the solvent. Three possible aqueous solutions can be formed:saturated, unsaturated and supersaturated.

Boiling Point Elevation

Boiling Point Elevation is the phenomenon when adding a solute to a pure solvent results in increased boiling point of the solvent.

Intro to Henry's Law

According to&nbsp;Henry's Law, at a constant temperature the amount of a gas dissolved in a solvent is directly proportional to its partial pressure when it is in equilibrium with its liquid phase.&nbsp;

Osmotic Pressure

Osmotic Pressure is the force that drives Osmosis from higher concentration to lower concentration.

Mole Fraction

Mole Fraction (X) relates the moles of solute and solvent within a solution.&nbsp;

The Colligative Properties

The&nbsp;Colligative Properties&nbsp;explain what happens to a pure solvent as it transitions to a solution.

Molality (m)&nbsp;represents the number of moles of solute dissolved per kilogram of solvent.&nbsp;

Freezing Point Depression

Freezing Point Depression is the phenomenon when adding a solute to a pure solvent results in decreased freezing point of the solvent.

Solutions: Solubility and Intermolecular Forces

Solutions are homogeneous mixtures that result from the dissolving of a solute by a solvent.

Vapor Pressure Lowering (Raoult's Law)

Vapor Pressure is the pressure exerted by a gas at equilibrium with its liquid phase at a specific temperature in a closed system.

Henry's Law Calculations

To calculate solubility of a dissolves gas, Henry's Law Constant and partial pressure are used.

Solutions: Mass Percent

Mass Percent represents grams of solute per grams of solution, multiplied by 100.

Osmosis

Osmosis is the net movement of solvent across a semipermeable membrane.

Parts per Million (ppm)

<div dir="auto"><div contenteditable="true"dir="auto"spellcheck="true">Parts per Million (ppm) and Parts per Billion (ppb) are used to express extremely dilute solution concentrations.</div></div>