Difference between revisions of "Molarity"
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==Key Stage 3== | ==Key Stage 3== | ||
===Meaning=== | ===Meaning=== | ||
| − | [[Molarity]] is | + | [[Molarity]] is a[[unit]] of [[concentration]] of [[solution]]s. |
===About Molarity=== | ===About Molarity=== | ||
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: The [[molarity]] of [[Stomach Acid]] is around 0.16 '''Molar''' (0.16M). | : The [[molarity]] of [[Stomach Acid]] is around 0.16 '''Molar''' (0.16M). | ||
: The [[molarity]] of [[Battery Acid]] can be as much as 5.2 '''Molar''' (5.2M). | : The [[molarity]] of [[Battery Acid]] can be as much as 5.2 '''Molar''' (5.2M). | ||
| + | |||
| + | ==Key Stage 4== | ||
| + | ===Meaning=== | ||
| + | [[Molarity]] is a [[unit]] of [[concentration]] of [[solution]]s in mol/dm<sup>3</sup>. | ||
| + | |||
| + | ===About Molarity=== | ||
| + | : [[Molarity]] is shortened with an upper case '''M'''. | ||
| + | : [[Molarity]] is the [[ratio]] of the number of [[mole]]s of a [[solute]] to the [[Volume (Space)|volume]] of [[solvent]]. | ||
| + | : When [[molarity]] is used to describe a [[solution]] it may be referred to as '''molar''', eg. a 0.5 '''molar''' [[solution]] of [[Sodium Chloride]]. | ||
| + | : Bottles containing [[acid]] and [[alkali]] usually have their [[Molarity]] stated on the side. The more [[concentrated]] the higher the [[molarity]]. | ||
| + | |||
| + | ===Equation=== | ||
| + | '' '''concentration (mol/dm<sup>3</sup>)''' '' = <math>\frac{Moles (mol)}{volume (dm^3)}</math> | ||
| + | |||
| + | Where: | ||
| + | : Moles = The number of [[mole]]s of the [[solute]]. Found by dividing the [[mass]] in [[gram]]s by the [[Relative Formula Mass|relative formula mass]]. | ||
| + | : volume = The [[Volume (Space)|volume]] of [[solvent]]. | ||
| + | |||
| + | |||
| + | {| class="wikitable" | ||
| + | |- | ||
| + | | style="height:20px; width:300px; text-align:center;" |117g of [[NaCl]] is [[dissolve]]d in 0.5dm<sup>3</sup> of [[water]]. Calculate the [[concentration]] in g/dm<sup>3</sup>. | ||
| + | | style="height:20px; width:300px; text-align:center;" |28g of [[KOH]] is [[dissolve]]d in 100ml of [[water]]. Calculate the [[concentration]] in g/dm<sup>3</sup>. | ||
| + | | style="height:20px; width:300px; text-align:center;" |73g of [[HCl]] is [[dissolve]]d in 400ml of [[water]]. Calculate the [[concentration]] in g/dm<sup>3</sup>. | ||
| + | |- | ||
| + | | style="height:20px; width:200px; text-align:left;" | | ||
| + | '''Find the number of [[mole]]s.''' | ||
| + | [[mass]] = 117g | ||
| + | |||
| + | [[Relative Formula Mass]] = 58.5g | ||
| + | |||
| + | Number of [[Mole]]s of a [[Compound]] = ([[Mass]] of [[compound]])/([[Relative Formula Mass]] of [[compound]]) | ||
| + | |||
| + | Number of [[Mole]]s = <math>{\frac{m}{M_r}}</math> | ||
| + | |||
| + | Number of [[Mole]]s = <math>{\frac{117}{58.5}}</math> | ||
| + | |||
| + | Number of [[Mole]]s = 2mol | ||
| + | |||
| + | |||
| + | | style="height:20px; width:200px; text-align:left;" | | ||
| + | '''State the [[mass]] in [[gram]]s and the [[Volume (Space)|volume]] in dm<sup>3</sup>:''' | ||
| + | '''Find the number of [[mole]]s.''' | ||
| + | [[mass]] = 28g | ||
| + | |||
| + | [[Relative Formula Mass]] = 56g | ||
| + | |||
| + | Number of [[Mole]]s of a [[Compound]] = ([[Mass]] of [[compound]])/([[Relative Formula Mass]] of [[compound]]) | ||
| + | |||
| + | Number of [[Mole]]s = <math>{\frac{m}{M_r}}</math> | ||
| + | |||
| + | Number of [[Mole]]s = <math>{\frac{28}{56}}</math> | ||
| + | |||
| + | Number of [[Mole]]s = 0.5mol | ||
| + | | style="height:20px; width:200px; text-align:left;" | | ||
| + | '''Find the number of [[mole]]s.''' | ||
| + | [[mass]] = 73g | ||
| + | |||
| + | [[Relative Formula Mass]] = 36.5g | ||
| + | |||
| + | Number of [[Mole]]s of a [[Compound]] = ([[Mass]] of [[compound]])/([[Relative Formula Mass]] of [[compound]]) | ||
| + | |||
| + | Number of [[Mole]]s = <math>{\frac{m}{M_r}}</math> | ||
| + | |||
| + | Number of [[Mole]]s = <math>{\frac{73}{36.5}}</math> | ||
| + | |||
| + | Number of [[Mole]]s = 2mol | ||
| + | |- | ||
| + | | style="height:20px; width:300px; text-align:left;" | | ||
| + | [[Volume (Space)|volume]] = 0.5dm<sup>3</sup> | ||
| + | | style="height:20px; width:300px; text-align:left;" | | ||
| + | [[Volume (Space)|volume]] = 100ml | ||
| + | |||
| + | The [[Volume (Space)|volume]] must be converted into dm<sup>3</sup> from ml. | ||
| + | |||
| + | [[Volume (Space)|volume]] in dm<sup>3</sup> = ([[Volume (Space)|volume]] in ml)/1000 | ||
| + | |||
| + | [[Volume (Space)|volume]] = 0.1dm<sup>3</sup> | ||
| + | | style="height:20px; width:300px; text-align:left;" | | ||
| + | [[Volume (Space)|volume]] = 400ml | ||
| + | |||
| + | The [[Volume (Space)|volume]] must be converted into dm<sup>3</sup> from ml. | ||
| + | |||
| + | [[Volume (Space)|volume]] in dm<sup>3</sup> = ([[Volume (Space)|volume]] in ml)/1000 | ||
| + | |||
| + | [[Volume (Space)|volume]] = 0.4dm<sup>3</sup> | ||
| + | |||
| + | |- | ||
| + | | style="height:20px; width:300px; text-align:left;" | | ||
| + | '''Calculate the Concentration:''' | ||
| + | |||
| + | '' '''concentration (mol/dm<sup>3</sup>)''' '' = <math>\frac{Moles (mol)}{volume (dm^3)}</math> | ||
| + | |||
| + | '' '''concentration''' '' = <math>\frac{2}{0.5}</math> | ||
| + | |||
| + | '' '''concentration''' '' = 4mol/dm<sup>3</sup> = 4M | ||
| + | | style="height:20px; width:300px; text-align:left;" | | ||
| + | '''Calculate the Concentration:''' | ||
| + | |||
| + | '' '''concentration (mol/dm<sup>3</sup>)''' '' = <math>\frac{Moles (mol)}{volume (dm^3)}</math> | ||
| + | |||
| + | '' '''concentration''' '' = <math>\frac{0.5}{0.1}</math> | ||
| + | |||
| + | '' '''concentration''' '' = 5mol/dm<sup>3</sup> = 5M | ||
| + | | style="height:20px; width:300px; text-align:left;" | | ||
| + | '''Calculate the Concentration:''' | ||
| + | |||
| + | '' '''concentration (mol/dm<sup>3</sup>)''' '' = <math>\frac{mass (g)}{volume (dm^3)}</math> | ||
| + | |||
| + | '' '''concentration''' '' = <math>\frac{2}{0.4}</math> | ||
| + | |||
| + | '' '''concentration''' '' = 5mol/dm<sup>3</sup> = 5M | ||
| + | |} | ||
Revision as of 11:33, 12 January 2019
Contents
Key Stage 3
Meaning
Molarity is aunit of concentration of solutions.
About Molarity
- Molarity is shortened with an upper case M.
- When molarity is used to describe a solution it may be referred to as molar, eg. a 0.5 molar solution of Sodium Chloride.
- Bottles containing acid and alkali usually have their Molarity stated on the side. The more concentrated the higher the molarity.
- The molarity of Stomach Acid is around 0.16 Molar (0.16M).
- The molarity of Battery Acid can be as much as 5.2 Molar (5.2M).
Key Stage 4
Meaning
Molarity is a unit of concentration of solutions in mol/dm3.
About Molarity
- Molarity is shortened with an upper case M.
- Molarity is the ratio of the number of moles of a solute to the volume of solvent.
- When molarity is used to describe a solution it may be referred to as molar, eg. a 0.5 molar solution of Sodium Chloride.
- Bottles containing acid and alkali usually have their Molarity stated on the side. The more concentrated the higher the molarity.
Equation
concentration (mol/dm3) = \(\frac{Moles (mol)}{volume (dm^3)}\)
Where:
- Moles = The number of moles of the solute. Found by dividing the mass in grams by the relative formula mass.
- volume = The volume of solvent.
| 117g of NaCl is dissolved in 0.5dm3 of water. Calculate the concentration in g/dm3. | 28g of KOH is dissolved in 100ml of water. Calculate the concentration in g/dm3. | 73g of HCl is dissolved in 400ml of water. Calculate the concentration in g/dm3. |
|
Find the number of moles. mass = 117g Relative Formula Mass = 58.5g Number of Moles of a Compound = (Mass of compound)/(Relative Formula Mass of compound) Number of Moles = \({\frac{m}{M_r}}\) Number of Moles = \({\frac{117}{58.5}}\) Number of Moles = 2mol
|
State the mass in grams and the volume in dm3: Find the number of moles. mass = 28g Relative Formula Mass = 56g Number of Moles of a Compound = (Mass of compound)/(Relative Formula Mass of compound) Number of Moles = \({\frac{m}{M_r}}\) Number of Moles = \({\frac{28}{56}}\) Number of Moles = 0.5mol |
Find the number of moles. mass = 73g Relative Formula Mass = 36.5g Number of Moles of a Compound = (Mass of compound)/(Relative Formula Mass of compound) Number of Moles = \({\frac{m}{M_r}}\) Number of Moles = \({\frac{73}{36.5}}\) Number of Moles = 2mol |
|
volume = 0.5dm3 |
volume = 100ml The volume must be converted into dm3 from ml. volume in dm3 = (volume in ml)/1000 volume = 0.1dm3 |
volume = 400ml The volume must be converted into dm3 from ml. volume in dm3 = (volume in ml)/1000 volume = 0.4dm3 |
|
Calculate the Concentration: concentration (mol/dm3) = \(\frac{Moles (mol)}{volume (dm^3)}\) concentration = \(\frac{2}{0.5}\) concentration = 4mol/dm3 = 4M |
Calculate the Concentration: concentration (mol/dm3) = \(\frac{Moles (mol)}{volume (dm^3)}\) concentration = \(\frac{0.5}{0.1}\) concentration = 5mol/dm3 = 5M |
Calculate the Concentration: concentration (mol/dm3) = \(\frac{mass (g)}{volume (dm^3)}\) concentration = \(\frac{2}{0.4}\) concentration = 5mol/dm3 = 5M |