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Questions and Answers
What is the molar concentration of a solution with 5g of NaCl (58.5g/mol) in 1L of water?
What is the molar concentration of a solution with 5g of NaCl (58.5g/mol) in 1L of water?
If a solution contains 3 moles of glucose (180g/mol) in 2 liters, what is its molarity?
If a solution contains 3 moles of glucose (180g/mol) in 2 liters, what is its molarity?
What is the normality of a solution containing 0.5 equivalents of HCl (36.5g/mol) in 500ml?
What is the normality of a solution containing 0.5 equivalents of HCl (36.5g/mol) in 500ml?
If 4g of Ca(OH)2 (74g/mol) is dissolved in 1L of water, what is its normality?
If 4g of Ca(OH)2 (74g/mol) is dissolved in 1L of water, what is its normality?
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Which method is commonly used to express the concentration of commercial aqueous reagents?
Which method is commonly used to express the concentration of commercial aqueous reagents?
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In molarity calculations, what should be used to determine the number of moles of a solute?
In molarity calculations, what should be used to determine the number of moles of a solute?
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What is the molarity of a solution if 0.25 moles of CH3OH (32g/mol) are dissolved in 500ml?
What is the molarity of a solution if 0.25 moles of CH3OH (32g/mol) are dissolved in 500ml?
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How can normality be calculated for a salt in a solution?
How can normality be calculated for a salt in a solution?
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What does a 70% (w/w) solution of nitric acid mean?
What does a 70% (w/w) solution of nitric acid mean?
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What does a 5% (v/v) aqueous solution of methanol mean?
What does a 5% (v/v) aqueous solution of methanol mean?
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What does a 5% (w/v) aqueous silver nitrate solution indicate?
What does a 5% (w/v) aqueous silver nitrate solution indicate?
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In parts per million (ppm), what does 1 ppm represent?
In parts per million (ppm), what does 1 ppm represent?
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What does volume percent commonly specify?
What does volume percent commonly specify?
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How is weight to volume percent commonly used?
How is weight to volume percent commonly used?
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Study Notes
Molar Concentration (Molarity)
- Molarity is the number of moles of a solute in 1 liter of solution.
- It is calculated by dividing the number of moles of solute by the volume of solution in liters.
- Example: Calculate the molar concentration of ethanol in an aqueous solution that contains 2.30g of C2H5OH (46g/mol) in 3.50 L of solution.
Molarity Problems
- Calculate the molar concentration of a solution of NaOH (40g/mol) in which 0.4g NaOH dissolved in 500ml solution.
- Calculate the molarity of a solution of sodium metal (23g/mol) in which 0.115g of pure sodium metal was dissolved in 500ml distilled water.
Normal Concentration (Normality)
- Normality is the number of equivalents of solute that is contained in 1 L of solution.
- For acids, normality is calculated by dividing the number of moles of solute by the number of replaceable H+ ions.
- For bases, normality is calculated by dividing the number of moles of solute by the number of replaceable OH- ions.
- For salts, normality is calculated by dividing the number of moles of solute by the total number of positive or negative charge.
- Example: Find the normality of H2SO4 (98g/mol) having 49g of H2SO4 present in 500ml of solution.
Percent Concentration
- Percent concentration is a way to express concentrations in terms of percent (parts per hundred).
- There are three common methods: weight percent, volume percent, and weight to volume percent.
- Weight percent is often used to express the concentration of commercial aqueous reagents.
- Volume percent is commonly used to specify the concentration of a solution prepared by diluting a pure liquid compound with another liquid.
- Weight to volume percent is often used to indicate the composition of dilute aqueous solutions of solid reagents.
- Example: A solution was prepared by dissolving 2.45 g of AgNO3 in sufficient water to give 40 mL, calculate the w/v percent of AgNO3.
Parts per Million (ppm)
- Parts per million is a convenient way to express concentration for very dilute solutions.
- A handy rule is to remember that for dilute aqueous solutions whose densities are approximately 1.00 g/mL, 1 ppm = 1.00 mg/L.
Dilution
- When a solution is diluted, the normality of the diluted solution is decreased.
- Example: A 20 ml of 10 N HCl are diluted with distilled water to form one liter of the solution, what is the normality of the diluted solution?
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Description
Test your understanding of molarity with these practice questions. Calculate the molar concentration of solutes in different solutions using the given data. Perfect for students studying chemistry or anyone wanting to improve their knowledge of molarity calculations.
