2.5.1 Concentration of Solutions

• What are the two main units used to express concentration?

  mol/dm³ and g/dm³
• A solution with 5 grams of solute in 1 litre has a concentration of 5 g/dm³.


  True
• What is the concentration in g/dm³ of a solution with 5 grams of solute in 1 litre?

  5 g/dm³
• What does molarity measure?

  Moles of solute per litre
• Molarity is expressed in units of mol/L
• In the molarity formula, \( V \) represents the volume of the solution in litres
• Concentration measures the amount of a solute dissolved in a specific volume of solution.
• Moles per cubic decimetre (mol/dm³) measures the number of moles of solute per litre of solution.
• Concentration can be calculated using the mass of the solute and the volume of the solution.
• The molarity of a solution containing 0.25 moles of potassium hydroxide in 500 mL of water is 0.5 mol/L.
• What is the formula for calculating molarity?

  $C =$$\frac{n}{V}$
• What is the molarity of a solution containing 0.25 moles of KOH in 500 mL of water?

  0.5 mol/L
• To convert from g/dm³ to mol/dm³, you must divide by the molar mass
• What is the concentration in g/dm³ of a 0.25 mol/dm³ solution of NaCl (molar mass = 58.44 g/mol)?

  14.61 g/dm³
• Concentration can be calculated by dividing the mass or moles of solute by the volume of the solution
• What is the formula for calculating concentration in mol/dm³?

  C = \frac{n}{V}</latex>
• A solution with 5 grams of solute in 1 litre has a concentration of 5 g/dm³.


  True
• The formula to calculate molarity is $C =$$\frac{n}{V}$
• Molarity refers to the number of moles of solute dissolved in one litre of solution.


  True
• The number of moles of solute is represented by \( n \) in the molarity formula.


  True
• What is the formula for calculating concentration in moles per cubic decimetre?

  $C =$$\frac{n}{V}$
• Grams per cubic decimetre (g/dm³) measures the mass of solute in grams per litre of solution.

  True
• What is the concentration of a solution containing 25 grams of sodium chloride in 500 mL of water?

  50 g/L
• What is the concentration of the sodium chloride solution in g/L?

  50 g/L
• In the molarity formula, 'n' represents the number of moles
• Converting between mol/dm³ and g/dm³ requires knowledge of the solute's molar mass
• A solution contains 30 g/dm³ of glucose. What is its concentration in mol/dm³ if the molar mass of glucose is 180.16 g/mol?

  0.166 mol/dm³
• To convert from g/dm³ to mol/dm³, you must divide by the solute's molar mass.
• Match the conversion type with its formula:

  mol/dm³ to g/dm³ ↔️ $C_{g} =$$C_{mol} \times M$

  g/dm³ to mol/dm³ ↔️ $C_{mol} =$$\frac{C_{g}}{M}$
• Steps to convert concentration from mol/dm³ to g/dm³

  1️⃣ Identify the molar mass of the solute

  2️⃣ Apply the formula: $C_{g} =$$C_{mol} \times M$

  3️⃣ Calculate the concentration in g/dm³
• To calculate the concentration in mol/dm³, you divide the number of moles by the volume in litres.
• What does the unit 'moles per cubic decimetre' measure?

  Moles of solute per litre
• In the formula for concentration, 'n' represents the number of moles
• Steps to calculate the concentration of a solution using mass per unit volume

  1️⃣ Convert the volume from mL to litres

  2️⃣ Apply the formula $C =$$\frac{m}{V}$

  3️⃣ Calculate the concentration
• What is the formula for calculating concentration using mass and volume?

  $C =$$\frac{m}{V}$
• What does \( C \) represent in the molarity formula?

  Concentration
• What is the concentration of a solution containing 0.5 moles of potassium hydroxide in 2 litres of water?

  0.25 mol/L
• What is the formula for calculating concentration in grams per cubic decimetre?

  $C =$$\frac{m}{V}$
• What is the concentration of a solution containing 0.25 moles of solute in 0.5 dm³ of solution?

  0.5 mol/dm³
• Molarity measures the number of moles of solute dissolved in one litre of solution.

  True