Solutions

//Solutions // A solution is a homogenous mixture of solutes and solvents. For example Sugar in water. This is a solutions because the sugar dissolves in the water. A solution comprises of a **solute** and a **solvent**.

 //The solvent is the component of the solution that is present in larger quantities.// Water in this example is the solvent.

// The solute is the component of the solution that is present in smaller quantities. // Sugar in this example is the solute.

Also the gasses in the air form a solution. In the case of air, Nitrogen gas is the solvent since it is present in larger quantities (about 79%). Oxygen is the solute since it is present in smaller quantities (about 20%).

**So, What is concentration?? L **

Concentration is the amount of solute per unit volume of the solution. In other words, the concentration measures the amount of solute dissolved in a given volume of the solution. It can be calculated using the below equation:



In short the formula is:  //The units for concentration is mol dm -3. //

Concentration is also referred to as **‘Molarity**’.

//Question:// Calculate the concentration of the solution formed when 4 mol of C 6 H 12 O 6 (glucose) is dissolved in 5 litre of water?



//Question:// What mass of hydrated copper(II) sulphate crystals (CuSO 4 .5H 2 O) is present in 17.3 cm 3 of a 0.279 mol dm -3 solution of copper sulphate.

You can solve this question as follows:

<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Volume of solution = 17.3 cm 3 =

<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Rearranging the formula gives => n=cv = 0.0173 dm 3 x 0.279 mol dm -3 = 0.00483 mol of CuSO 4

<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Molar mass of CuSO 4 .5H 2 O = 249.55 g

<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Mass of CuSo 4 .5H 2 O produced = 249.55 x 0.00483 = 1.21 g

//<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">The concentration is often indicated by square brackets [] eg: // //<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">[HCl] means the concentration of hydrochloric acid. // <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">

<span style="color: #274be7; font-family: Tahoma,sans-serif; font-size: 110%;">By the end of this lesson you should be able to:

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 * Define the terms solute, solvent, solution and concentration
 * Solve questions involving the concentration, amount of solute and volume of a solution