# Moles and solutions

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• Created by: racheon
• Created on: 24-02-14 19:06
Define concentration.
The amount of solute, in mol, dissolved per 1dm³ of solution.
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In a solution, what does the solute dissolve in?
The solvent.
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What is concentration measured in?
mol dm-³.
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In a solution with a concentration of 2 mol dm-³ how many moles are there in 1dm³, 2dm³ and 0.25dm³ of the dissolved solute?
1dm³ contains 2 mol, 2dm³ contains 4 mol, and 0.25dm³ contains 0.5 mol.
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If you know the concentration of a solution what can you find?
The amount of moles in any volume of the solution.
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What is the equation for working out the amount of moles in a solution?
n (amount of substance) = c (concentration of solute) x V (volume in dm³ of a solution) or n = c x [V (in cm³) ÷ 1000].
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What is the amount, in mol, of NaOH dissolved in 25cm³ of an aqueous solution of concentration 0.0125 mol dm-³?
n (NaOH) = c x (V ÷ 1000) = 0.0125 x (25 ÷ 1000) = 3.125 x 10-⁴mol.
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Define standard solution.
A solution of known concentration. They are normally used in titrations to determine unknown information about another substance.
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How do you make a standard solution?
1. Consider the volume of solution required. 2. Work out the amount of solute needed. 3. Convert this into a mass so you know how much to weigh out.
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Find the mass of potassium hydroxide required to prepare 250cm³ of a 0.2 mol dm-³ solution, and how many grams do you need in 1dm³ of the solution?
1. Find the amount of KOH required in the solution: n (KOH) = c x (V ÷ 1000) = 0.2 x (250 ÷ 1000) = 0.05mol. 2. Convert moles to grams: molar mass = 39.1 + 16 +1 = 56.1 g mol-¹. n = m ÷ n. Hence, m = n x M=0.05x56.1=2.805g, and 11.22g or 11.22g dm-³.
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Define mass concentration.
The mass dissolved in 1dm³ of solution.
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What is mass concentration measured in?
g dm-³.
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Define concentrated.
A large amount of solute per dm³.
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Define dilute.
A small amount of solute per dm³.
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What other term means the same as 2 mol dm-³?
2M.
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## Other cards in this set

### Card 2

#### Front

In a solution, what does the solute dissolve in?

The solvent.

### Card 3

#### Front

What is concentration measured in?

### Card 4

#### Front

In a solution with a concentration of 2 mol dm-³ how many moles are there in 1dm³, 2dm³ and 0.25dm³ of the dissolved solute?

### Card 5

#### Front

If you know the concentration of a solution what can you find?